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This dissertation presents a new class of power converter topologies that realize galvanic
isolation by utilizing active transistor devices instead of conventional transformers.
The power converters employ standard switch-mode topologies but isolate the
ground connections with the addition of active switches on the ground side of the
power path. Compared to transformer isolation, the Active Isolated (AI) converters
have reduced size and cost with increased efficiency. A generalized approach is given
that is used to create thrity-six new active isolated topologies based on the following
basic converters: buck, boost, buck-boost, Cuk, SEPIC, and Zeta. Of these, the
buck-boost and boost-buck are determined optimum topologies since they achieve
pulsating and non-pulsating galvanic isolated conversion with the fewest component
count, respectively. The two optium converters are modeled mathematically and various
protoypes are developed that confirms proper galvanic isolation. The concept of
unipolar and bipolar isolation is explored and it is found that in many applications,
including the application choosen for this work, that unipolar isolation is adequate
to provide proper operation and safety for the user. Commom-mode transient and
steady-state models of the converters are developed and correlated to experimental
results. The two optimum convertes are used in two appliations: PV microinverter
and offline AC-DC power supply with fault protection.
MICHELLE B. PASS. Staying the course: the persistence of African American biology majors at a predominantly White Institution. (Under the direction of Dr. CHANCE W. LEWIS)
Increasing the number of African Americans graduating with STEM degrees and entering the STEM workforce has been the focus of countless political reports and educational studies for decades; however, African Americans continue to experience waning graduation rates and mounting attrition rates in STEM disciplines while remaining vastly underrepresented in STEM fields. This study differs from previous studies that have focused on African Americans in STEM utilizing a deficit-based approach. This qualitative, phenomenological study examined the experiences of African American students who were successfully navigating the biology major at a predominantly White institution. This study sought to identify the factors that support the persistence of African American students in the biology major at a predominantly White institution, and to describe how these factors support their persistence in the biology major. Data were collected through in-depth interviews with six African American undergraduate biology students and analyzed using phenomenological analysis. Findings revealed that although the students were successful in the biology major, the lack of support from professors and peers within the biology major, adversely affected their academic and social experiences. Four themes emerged from the analysis of interview data. The themes are: self-determination, peer-support, independence, and adaptation. Recommendations for educational stakeholders and future research are discussed.
Recent advances in Deep Learning have made possible distributed multi-camera IoT vision analytics targeted at a variety of surveillance applications involving automated real-time analysis of events from multiple video perspectives. However, the latency sensitive nature of these applications necessitates computing at the Edge of the network, close to the cameras. The required Edge computing infrastructure is necessarily distributed, with Cloud like capabilities such as fault tolerance, scalability, multi application tenancy, and security, while functioning at the unique operating environment of the Edge. Characteristics of the Edge include, highly heterogeneous hardware platforms with limited computational resources, variable latency wireless networks, and minimal physical security. We postulate that a distributed publish-subscribe
messaging system with storage capabilities is the right abstraction layer needed for multi-camera vision Edge analytics.
We propose Mez - a publish-subscribe messaging system for latency sensitive multi-camera machine vision at the IoT Edge. Unlike existing messaging systems, Mez allows applications to specify latency, and application accuracy bounds. Mez implements a network latency controller that dynamically adjusts the video frame quality to satisfy latency, and application accuracy requirements. Additionally, the design of Mez utilizes application domain specific features to provide low latency operations.
In this dissertation, we show how approximate computation techniques can be used to design the latency controller in Mez. We also present the design of Mez by describing its API, data model and architecture. Additionally, Mez incorporates an in-memory log based storage that takes advantage of specific features of machine vision applications to implement low latency operations. We also discuss the fault tolerance capabilities of the Mez design.
Experimental evaluation on an IoT Edge testbed with a pedestrian detection machine vision application indicates that Mez is able to tolerate latency variations of up to 10x with a worst-case reduction of 4.2% in the application inference accuracy. Further we investigated two approximate computing based algorithms - a heuristic based
pruning algorithm and a Categorical boost machine learning model based algorithm, to make the Mez’s latency controller design scalable. Both algorithms were able to achieve video frame size reduction upto 71.3% while attaining an inference accuracy of 80.9% of that of the unmodified video frames.
In recent years, emotion detection in text has become more popular due to its vast potential applications in marketing, political science, psychology, human-computer interaction, artificial intelligence, etc. Access to a huge amount of textual data, especially opinionated and self-expression text, also played a special role in bringing attention to this field. In this work, we review the work that has been done in identifying emotion expressions in text and argue that although many techniques, methodologies, and models have been created to detect emotion in text, these methods, due to their handcrafted features and lexicon-based nature, are not capable of capturing the nuance of emotional language. By losing the information in the sequential nature of the text, and inability to capture the context, these methods cannot grasp the intricacy of emotional expressions, therefore, are insufficient to create a reliable and generalizable methodology for emotion detection. By understanding these limitations, we present our deep neural network methodology based on bidirectional GRU and attention mechanism and the fine-tuned transformer model (BERT) to show that we can significantly improve the performance of emotion detection models by capturing more informative text representation. Our results show a huge improvement over conventional machine learning methods on the same dataset with an average of 26.8 point increase in F-measure on the test data and a 38.6 point increase on a new dataset unseen by our model. We Show that a bidirectional-GRU with attention could perform slightly better than BERT. We also present a new methodology to create emotionally fitted embeddings and show that these embeddings perform up to 13% better in emotion similarity metrics.
The essential oil (EO) industry continues to grow as consumers search for more alternative and complementary therapies. When possible, EO users are quick to turn to EOs for basic medical ailments instead of traditional medications/pharmaceuticals. With the continually high growth of EO consumers, the scientific research to support their many applications is inadequate. Due to the large gap in EO research, users do not have enough scientifically proven sources to aid in their understanding of these oils. There is a crucial need for more EO related research. A large portion of my dissertation work will provide a solid platform for users to educate themselves on EOs from a scientifically driven stand point. It will also provide new data and insights on the application and molecular mechanisms of Boswellia carterii (frankincense) EO for targeting inflammation.
ABSTRACT
REX A. MANGIARACINA. A QUALITATIVE STUDY OF THE PERCEPTIONS OF BEGINNING PK–12 PUBLIC EDUCATION TEACHERS ON DEFINED BENEFIT RETIREMENT PLANS. (Under the direction of DR. WALTER HART.)
The significance of this study was its ability to further inform beginning PK–12 public education teachers and policy makers on the issue of teacher compensation. More specifically, the study shed light on beginning teachers’ limited understanding of their defined benefit (DB) retirement plans. The purpose of this basic interpretive qualitative study was to gain additional insight and further explore the perceptions and understanding of these teachers about their DB retirement plans. The study sought further understanding as to what these teachers knew about their DB retirement plans, how they developed this understanding, how this understanding impacted their sense of financial security upon retirement, and what if any effect this understanding had in terms of impacting their career decisions. A basic interpretative qualitative study, the researcher’s data sources for this study involved semi-structured, one-on-one interviews with beginning PK–12 public education teachers. Results of the study indicate that these teachers lacked clarity about their existing DB retirement plan as well as understanding of retirement plan options more broadly. Results indicate a struggle for these teachers to establish a relationship between their retirement benefits and financial security as well as the ability to make informed career decisions based on adequate understanding of retirement plan options. Implications included the need for related professional development for beginning teachers characterized by strategic planning, delivery, and ongoing evaluation along with the need for additional research.
The dissertation consists of three essays. The first essay examines how a tournament among CEOs to progress within the CEO labor market changes their tendency toward corporate hedging policies. We exploit the textual analysis of 10-Ks to generate corporate hedging proxies. We find that the likelihood and intensity to hedge increases as the CEO labor market tournament prizes augment. We explore the mitigating impacts of corporate hedging on the adverse effects of risk-inducing industry tournament incentives (ITIs) on the cost of debt and stock price crash risk, which could be the possible reasons for the relation. Also, the relation between ITIs and corporate hedging is less pronounced for firms that demonstrate more financial distress and when CEOs are the founders or of retirement age. We identify a causal relation between ITIs and corporate hedging by using an instrumental variable approach and an exogenous shock sourced by the changes in the enforceability of non-competition agreements across states.
In the second essay, the effects of internal tournament incentives (ITTIs) on reserve management, performance and risk-taking in property-liability insurance firms are studied. We find that a positive relation between ITTIs and reserve errors, implying that a higher tournament prize is associated with more conservative loss reserve management. Unlike the literature on non-financial firms, we do not find a positive relation between ITTIs and risk-taking behavior or performance. The overall evidence indicates that VPs in tournaments focus on the strong financial health, not performance. Moreover, we find the positive impact of ITTIs on conservative reserve management is more pronounced for larger, financially weaker and more geographically focused firms, and is mitigated for insurers with a higher percentage of claim loss reserve over total liability. Our results also suggest that the Sarbanes Oxley Act does not significantly impact reserve behaviors of executives. Finally, we find that insurers with more independent board members are likely to have more conservative reserve behavior in internal tournaments.
In the third essay, we investigate the relation between executive pay duration and the cost of debt. We find a positive relation between equity-based pay duration (Equity PD) and loan spread, implying that loan spread is increasing in a larger Equity PD. However, we explore a negative relation between equity&debt-based pay duration (Whole PD) and loan spread, which shows that debt-like compensation contributes to the agency conflict between managers and creditors not only through their sizes but also through their durations. Also, we illustrate that the executive labor market is a channel that drives the relations of both Equity PD and Whole PD with the cost of debt. Risk and information asymmetry channels are the other channels through which Equity PD impacts the cost of debt. Lastly, we show the association between Whole PD and borrowing costs is more pronounced for firms with better corporate governance and past performance.
The volume of transfer students across college and university campuses in the United States continues to rise; however, institutions continue to struggle with identifying and applying best practices that encourage these students to earn their baccalaureate degree at rates comparable to their non-transferring peers. Prior research suggests many students experience transfer shock upon entering their new institution and that their performance outcomes may vary depending on their academic and social integration experiences (Cejda et al., 1998; Diaz, 1992; Eels, 1927; Hills, 1965; Ishitani, 2008; Knoell & Medsker, 1965; Laanan, 2001; Martorana & Williams, 1954; Nickens, 1972). To overcome these challenges, Tinto (1988, 1993) articulated the importance of integration, a key objective of the course studied in this research, as a means to more seamlessly assimilate into the new community resulting in a stronger institutional commitment, improved performance, and increased levels of retention. Further, Schlossberg (2011) built upon this concept utilizing her 4 S model to articulate the significance of support and strategies that individuals use to cope with and mitigate the challenges associated with periods of transition. Taken together, the transfer seminar course studied is seen as an interventional support and strategy aimed at improving the academic and social integration experience to potentially produce increased levels of success for transfer students.
The primary purpose of the current study was to measure the impact that a transfer seminar course had on individuals that participated in the course during their first semester of enrollment at the receiving institution, a large, public four-year state institution in the Southeastern United States. This quasi-experimental, quantitative study analyzed the impact of participation in a non-required transfer seminar course during the first semester of matriculation, post-transfer, and compared the grade point averages (GPA) and rates of persistence at the end of the first semester and first year with a matched sample of non-course participants to evaluate course impact. A total of 824 students, including 412 students in each of the treatment and control groups from Fall 2013 through Fall 2018 were evaluated utilizing descriptive and inferential statistical analyses.
The findings of the study revealed that the course participants exhibited a statistically significant difference in their GPA at the end of the first semester, but the difference in GPAs at the end of the first year had diminished and was non-statistically significant. The results further support that at the end of the first semester and at the end of the first year, rates of persistence were non-statistically significantly different for participants in comparison to non-participants. The conclusions presented suggest that the course provides only a short term positive gain for participants and may be most beneficial in assisting students transitioning into the new academic community, however, additional research is needed to identify resources, supports, strategies, and interventions that encourage greater levels of success over the long term period of matriculation through to graduation.
Among white people, there is a pervasive mentality that color-evasiveness (Bonilla-Silva, 2003) is an ideal approach to racial equity, meaning many white student affairs professionals may equate refusing to see race as synonymous with being anti-racist. The narrative that white people do not see color is problematic and inaccurate when, in actuality, it serves to maintains white dominance and white supremacy. In order to promote racial equity on college campuses, race needs to be illuminated, recognized, and reckoned with by white people to counter this ideology. The purpose of this qualitative study is to understand how white student affairs administrators describe being white and how whiteness impacts their work in student affairs. Utilizing ontological expansiveness, a critical phenomenological methodology, the researcher interviewed nine white student affairs administrators at a historically white university in the Southeast region of the United States. This university has established diversity and inclusion as one of its top values. All nine participants completed two semi-structured interviews. Data analysis methods included several line-by-line readings and the development of a code-book utilizing the conceptual framework of whiteness and essential concepts from the literature. As a result, six themes with corresponding sub-themes emerged: distance and proximity: the other side of the tracks, navigating judgement, values of whiteness, performative commitment, racism (in)action, and student affairs indoctrination. This study exemplified the ways whiteness permeated the division of student affairs, allowing for an in-depth understanding of the need for political and structural change, as well the need for genuine and authentic commitment by student affairs towards anti-racism.
While women have attained higher-level roles and greater representation in higher education administrator roles, the concept of the higher, the fewer (Nidiffer, 2002) represents the “gendered prestige hierarchies” (Allan, 2011, p. 58) that limit women’s representation at more prestigious institutions while bolstering representation at institutions of greater access. In student affairs, women represent a majority of all professionals in the field, though representation in senior student affairs officer roles has not increased significantly since the 1980s (Blackhurst, 2000), with women more likely to advance at institutions with fewer than 1,000 students (Rickard, 1985a). While extensive research exists that illustrates the disparities for women in higher education and academic affairs, little comparable research exists for women in student affairs.
This qualitative study sought to understand how women in senior-level student affairs positions have navigated their experiences and career paths in order to advance to their current roles. Using critical and post-structural feminist perspectives of power, the researcher utilized a critical phenomenological approach to consider how nine women in senior-level student affairs positions in large, public institutions understood their career advancement. Participants completed two semi-structured interviews. The resulting themes include an encompassing theme of genderization, as well as four embedded themes: the person on the path, achieving through and with others, conflicting messages of competence and value, and overtasked and alone. Implications of the study require that policy, practice, and research all examine the ways that genderization perpetuates masculine-centered norms and power dynamics that penalize women for deviating from those norms. For current or aspiring student affairs leaders, organizational constructs must be dismantled in order to disrupt internalized genderization by women.
