Dissertation Defense Announcements

Candidate Name: Ahmed Almhawes
Title: Academic Acceleration in Saudi Arabia
 April 09, 2024  2:30 PM
Location: SPCD Conference Room 344
Abstract:

Acceleration is one of the best-supported interventions available to gifted education practitioners internationally. However, the acceleration program in Saudi Arabia is still inchoate and could benefit from additional revision. The purpose of this research was to explore Saudi stakeholders’ perceptions regarding their lived experiences with the acceleration program implemented by the Saudi Ministry of Education beginning in 2014. To investigate, I used a qualitative research design and a phenomenological approach. Using semi-structured interviews, 18 Saudi stakeholders were interviewed within six clusters (i.e., three clusters comprising an accelerated gifted student, their parent, and their teacher, plus another three similar clusters with non-accelerated students). Following a thematic analysis method to categorize and synthesize these stakeholders’ perceptions, this approach revealed that Saudi stakeholders believed acceleration as a program was effective for Saudi gifted students. They perceived it as a convenient option, well aligned with gifted students’ characteristics, and as an appropriate recognition of these students’ superiority and dedication. The program was seen as the best available gifted program option in the Saudi context. Participants commended the acceleration intervention for positively affecting gifted students' academic performance. They believed that it provided challenging learning materials, fulfilled academic needs, and led to high grades, intelligence quotient (IQ) scores, and national standardized test scores. They also highlighted the importance of gaining advanced skills after completion. However, stakeholders also criticized the regulations and nomination procedures for the Saudi acceleration program, stating that the procedures were vague, not transparent, and unfair in geographical and other ways. All stakeholders also described a lack of awareness and preparation among teachers, parents, and students. Differences of opinion regarding the impact of this acceleration intervention on the social and emotional status of program participants also reveals contradictions. While some positive aspects included successful adaptation, balancing old and new friendships, maturity, and improved gifted characteristics, other responses mentioned potential negative impacts like anxiety and the pressure of high expectations from the students’ community. In general, Saudi stakeholders believed that the acceleration program positively impacts gifted students' future lives by enabling them to finish school earlier and more efficiently. Successful acceleration also led to scholarships, participation in national programs, and scientific trips, benefiting both society and these gifted students. Furthermore, the discussion revealed implications for practices and policies to improve the acceleration program’s regulation and implementation. Based on these findings, several future research directions are suggested.



Candidate Name: Amber Greenwood
Title: “I’m Just So Busy:” The Creation of a Busyness Façade as an Impression Management Tactic
 April 09, 2024  2:30 PM
Location: Cone 110
Abstract:

Busyness, or how busy someone is, has increasingly become a topic of conversation in day-to-day life. Research has previously explored how people use their time and how people perceive their available time, or lack thereof, but there is no clear answer as to why people tell others that they are busy and what it is they are trying to accomplish by doing so. Drawing on impression management research, this paper proposes that people signal to others that they are busy so that the audience has a positive impression of them. The concept of the busyness façade is introduced, which includes behaviors and verbal statements that are intentionally enacted by individuals to signal to others that they have a lot to do or limited available time. Exactly how and why people engage in this busyness façade is explored in two studies using semi-structured interviews and an online, vignette survey. Overall, evidence is found for the existence of busyness façades and a better understanding of how people display busyness is gained, but the studies are unable to identify a clear motive for why busyness façades would be used as an impression management tactic. Additional findings and research directions are discussed.



Candidate Name: Elijah Eddie Dunbar
Title: CULTURALLY RESPONSIVE PEDAGOGY AND ITS IMPACT ON THE ACADEMIC OUTCOMES OF MARGINALIZED STUDENTS (K-12) IN THE PEDAGOGICAL SPACES OF URBAN SCHOOLS: A PHENOMENOLOGICAL CASE STUDY
 April 09, 2024  2:00 PM
Location: https://charlotte-edu.zoom.us/j/93983683499
Abstract:

ABSTRACT
Culturally Responsive Teaching is a holistic pedagogical approach that appeals to the “whole child,” “whole school,” and “whole community” (Gay, 2001; Teschers, 2020); it is a multicultural practice that improves teaching and learning, promotes quality education, taps into the potential and uniqueness of students, and impacts learners intellectually, emotionally, kinesthetically, and physically (Gay, 2010; Widodo, 2019). This qualitative phenomenological case study examines the concepts and pedagogical practices of culturally responsive teaching through the shared experiences of educators and implementers of culturally responsive pedagogy to find out how effective those concepts and practices are in improving the academic outcomes of marginalized students (K-12) in urban classrooms. A purposive case sampling method (PCSM) and semi-structured interview were instrumental elements of the data collection process. A grounded theory method was used to both collect and analyze the data. Themes that emerged from the data of the interviews conducted with the participants were amalgamated to form four main themes for the study. Though this study may be limited by generalizability, it however provides answers to some lingering limitation questions of existing studies on culturally responsive practices. This study draws on and adds to the works of Geneva Gay on Culturally Responsive Pedagogy.
Keywords: holistic education, education equity, educational inequity, multicultural education, opportunity gap, culturally responsive pedagogy



Candidate Name: Oluwatimilehin Damilare Adeosun
Title: ADDRESSING PROTECTION CHALLENGES IN ELECTRIC POWER GRIDS WITH DISTRIBUTED GENERATION: A FOCUS ON DIRECTIONAL OVERCURRENT RELAYS
 April 09, 2024  2:00 PM
Location: EPIC 2224
Abstract:

The dissertation explores the challenges and transformations in modernizing the electrical grid, characterized by increased electric power grid interconnectivity, the widespread integration of Distributed Generation (DG), and frequent network reconfigurations. These transformations pose significant challenges to traditional grid technologies and operations, including power quality issues, protection scheme challenges, and complications in energy market dynamics. This study delves into the challenges of power system protection schemes from two perspectives: the misoperation of directional elements and the miscoordination of directional overcurrent elements. The proper operation of the protection system is critical to ensuring grid reliability.
The first perspective investigates the misoperation of directional elements; we model and analyze the fault behaviors of various generators, including Synchronous and Inverter-Based Generators (IBDGs) with differing control architecture, to comprehensively understand their fault characteristics. Furthermore, we explore the misoperation of negative sequence directional elements, proposing and validating a mitigation strategy using Real-Time Hardware-in-the-Loop (RT-HIL) setups.
The second perspective addresses the miscoordination of Directional Overcurrent Relays (DOCRs) and aims to minimize their operating times. The dissertation illustrates the advantages of employing optimization algorithms over numerical iteration methods for relay coordination. It examines the coordination performance using Genetic Algorithms (GA) and Particle Swarm Optimization (PSO), presenting an enhanced variation of PSO that yields improved performance validated through virtual HIL setups.
Additionally, the dissertation investigates the issue of DOCR miscoordination due to variations in fault current during fault isolation. It introduces a dynamic Time-Current Characteristic (TCC) formulation adapted to these variations, validated using IEEE test systems. It also investigates DG instability and miscoordination stemming from changes in network topology and generation short circuit capacity. A mitigation strategy that combines clustering and optimization algorithms is proposed and validated. Moreover, a co-optimization strategy is presented and validated to mitigate DOCR miscoordination while maintaining DG stability, ensuring that the Critical Clearing Time (CCT) associated with a fault is greater than the operating time of the relays assigned to isolate the fault.
This work significantly advances the understanding of how grid modernization impacts power system protection and lays the groundwork for future research in this evolving field. It highlights the need for a collaborative approach between inverter manufacturers and protection engineers to facilitate a seamless and reliable grid transformation.



Candidate Name: Rittika Mallik
Title: Casting a wider net: Using ray-finned fish genomes to gain novel insights into vertebrate molecular evolution
 April 09, 2024  2:00 PM
Location: Bioinformatics Room 402
Abstract:

The past decade has provided unprecedented insights into the molecular evolutionary pathways that have given rise to the present day diversity of vertebrates. Comparative genomic studies have repeatedly revealed that many key ecological traits, novel functional phenotypes, and even disease states are governed by genomic regions characterized by frequent mutations, duplications, or deletion events. However, the evolutionary origins and early diversification history of many of these regions remain poorly understood. My work focuses on providing a resolution to this history, focusing on the evolution of the vertebrate mobilome and a clustered gene family of innate immune receptors with putative links to the origin of the adaptive immune response. To accomplish this, I sequenced the genomes of Polypterus bichir and Lepisosteus osseus, two taxa that fill critical genomic sampling gaps for early diverging vertebrate lineages. Integrating these genomes into a comparative dataset of over 100 genomes that span all major ray-finned fish lineages, I investigated the effect of teleost genome duplication (TGD) on the diversification of the ray-finned fish mobilome. My findings reveal no substantial shift in mobilome composition following the TGD event, in line with a growing body of evidence that this historical ploidy event has not left a signature of a burst of molecular diversification and innovation across half of living vertebrates. I next expanded my taxonomic coverage to include all major vertebrate lineages to investigate the evolutionary origin of signal regulatory proteins (SIRPs) and their ligand CD47. In mammals, SIRPs are essential for regulating macrophage function and have become important targets for cancer therapy. These receptors also contain variable and joining exons and are hypothesized to have arisen in tetrapods out of a complex of innate immune receptor gene families that also gave rise to recombining T-cell receptors and antibody encoding Immunoglobulin domains. My work demonstrates this is not the case. Instead, SIRPs have evolutionary origins coincident with the origin of the adaptive immune response. In contrast, we find no evidence for an ancient origin of the CD47 ligand, which interacts with SIRPs. Instead, CD47 appears to have arisen at the beginning of amniote evolution, suggesting a decoupling of the evolutionary origins of this ligand and receptor pair. These findings provide a new perspective on the origins and diversification of innate immune receptor gene families and their relationship to the emergence of the adaptive immune system.



Candidate Name: Anthony Davis
Title: Student Conduct Administrators' Perceptions of Support
 April 09, 2024  1:00 PM
Location: COED 321C
Abstract:

Within the context of higher education, student conduct administration is drenched in risk, compliance with local and federal laws (Glick & Haug, 2020). In short, student conduct is a complex, and challenging functional area to work in, as administrators to balance educating students, protecting the campus community, and mitigating institutional risk (Miller & Sorochty, 2015; Lancaster & Waryold, 2008).

This qualitative, phenomenological study aimed to explore the lived professional experiences of student conduct administrators; to better understand their struggles and needs, as they would describe. Semi-structured interviews were used to capture depth in the shared experiences of ten participants and describe the meaning assigned to the phenomenon being explored.

The findings of this study were captured in 4 main themes: (1) Clashing with the Regime, which looks at SCAs challenges navigating political ecosystems within their respective institutions and states, (2) Encountering Turbulence, which captures common challenges SCAs experience while resolving cases (3) Nurtured by Leadership, which looks at the role of SCAs direct supervisor in fostering support and (4) Leaning on the Village, which captures the network of support SCAs receive outside of their direct supervisor.



Candidate Name: Wai-Lun Lam
Title: New version of optimal stopping problem
 April 09, 2024  12:30 PM
Location: Fretwell 315
Abstract:

This dissertation contains several new results concerning Moser-type optimal stopping problems. In the simplest case we consider sequence of independent uniformly distributed points X1, X2, · · · , Xn on the compact Riemannian manifold M and give algorithm for the calculation of Sn = maxτ≤nE[G(Xτ )]where G is a smooth function on M and τ is a random optimal stopping time. Description of the optimal τ depends on the structure of G near points of maximum. For different assumptions on this structure we calculate asymptotics of Sn.



Candidate Name: Jannatul Ferdous
Title: Optimization and Validation of SARS-CoV2 Sequencing from Clinical and Wastewater Samples
 April 09, 2024  11:00 AM
Location: BINF 305
Abstract:

The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in December 2019 triggered a global pandemic, causing the urgent need for effective surveillance measures to combat its spread and monitor the evolution of new variants. Sequencing SARS-CoV-2 is an essential tool for surveilling the circulating and emerging variants. This thesis addresses key challenges and proposes advancements in sequencing SARS-CoV-2, focusing on both clinical and wastewater samples.The primary objective of this thesis is to optimize sequencing protocols for SARS-CoV-2 variants from clinical and wastewater samples, specifically targeting improved sequencing capabilities for low viral concentrations using the Oxford Nanopore Promethion platform. Through protocol modifications and refinements, we achieved notable enhancements in sequencing output metrics, such as amplicon amplification, sequencing depth, and the generation of high-quality consensus sequences. The second objective evaluates the performance of wastewater deconvolution software for identifying SARS-CoV-2 variants, employing a meticulous assessment approach with controlled mixtures of synthetic variants and amplicon-based sequencing. In this objective we highlight the effectiveness of Freyja, a widely utilized tool, in producing variant abundance calls closely aligned with expected ratios. In the third objective, we investigate factors contributing to ambiguous variant calls in next-generation sequencing data from two distinct platforms, shedding light on potential sources of variability in variant abundance estimation. Through comprehensive analysis, significant disparities in genome coverage and mutation profiles between platforms were identified, suggesting possible biases or variations in error rates. While Freyja demonstrates excellent performance with controlled datasets, challenges arise with real-world wastewater samples. Through these objectives, the thesis aims to offer insights into optimizing sequencing protocols, enhancing variant detection algorithms, and improving data reproducibility across different sequencing technologies. Ultimately, this research contributes to ongoing efforts in infectious disease surveillance by advancing our understanding of SARS-CoV-2 sequencing from diverse sample sources and providing valuable guidance for future research in viral pathogen sequencing.



Candidate Name: Yi Wang
Title: ADVANCING COMMUNITY COLLEGE STUDENT ENGAGEMENT AND SUCCESS: VALIDATION STUDY OF COMMUNITY COLLEGE SURVEY OF STUDENT ENGAGEMENT (CCSSE)
 April 09, 2024  9:30 AM
Location: https://charlotte-edu.zoom.us/j/92443646830?pwd=bWFoaHVPSTVkb3p1bDkrVFlROFhWZz09
Abstract:

This three-article format dissertation presents a comprehensive examination of the 2017 Community College Survey of Student Engagement (CCSSE), focusing on its measurement properties across diverse community college student populations. Study 1 centered on the validity of the internal structure of CCSSE. Exploratory and confirmatory factor analyses showed evidence to support an eight-factor model of student engagement. This model encompasses dimensions such as personal development, interactions with faculty and peers, and institutional support. This study marks a methodological and theoretical shift, advocating for a multidimensional perspective on student engagement in community college. Study 2 employed multi-group confirmatory factor analysis to examine the measurement invariance of the CCSSE across gender, age, race/ethnicity, and enrollment intensity. The results affirmed the CCSSE’s capacity to consistently measure engagement at configural, metric, scalar, and strict levels measurement invariance. This verification underlined the survey’s reliability in capturing authentic group differences. This study also uncovered lower engagement scores among men and part-time students. Study 3 explored the concurrent and predictive evidence of validity of the CCSSE, investigating how engagement indicators correlate with and predict key student success outcomes. It offered new insights into the complex effects of factors such as interaction with faculty and peers and advising services on academic outcomes.



Candidate Name: Michael Zimnoch
Title: Cyclic Analysis of Power Plant Headers and Materials
 April 09, 2024  9:00 AM
Location: Duke 308
Abstract:

This dissertation evaluates the fatigue response of a steam header designed to mirror the specifications of an ex-service unit, with a focus on optimizing material selection through a detailed analysis involving cost, performance, and durability. Beginning with a study comparing three different alloy choices, 2.25Cr-1Mo, 9Cr-1Mo-V, and IN740H, headers are developed and compared using the procedures outlined in ASME BPVC. The design of the headers follows that used in the original development, and their performance is evaluated in representative loading transients. Each of the designs is evaluated for their fatigue response using the finite element program Abaqus. The results demonstrate that cost savings would likely outweigh any performance benefit to the current system.
The second portion evaluates the material characteristics of 2.25Cr-1Mo following years of exposure to a harsh operating environment. Material specimens were machined from the ex-service unit and subjected to uniaxial testing at various temperatures. The process is used to establish the Chaboche NLKH hardening coefficients. The selection of the NLKH model was guided by its capability to capture the cyclic behavior of the material. The material results are used to compare the projected performance of the 2.25Cr-1Mo header found using readily available material acquired from virgin specimens and those found from the existing unit. The results demonstrate a markedly reduced strength in the service-exposed material, illustrating the effects of the material transformation that occurs over time. This study highlights the importance of operational wear on the projected performance of the header.
The final portion introduces an automated crack growth algorithm in combination with Abaqus to model the progression of a seam crack within a 2.25Cr-1Mo header. Traditional fatigue assessments consider the formation of surface cracks as the end of usability. However, it is well established that the existence of cracks in headers may be allowable, depending on several factors such as size, location, and material. Additional challenges exist in headers along the tube-header intersections, which suffer from non-uniform crack propagation stemming from the complex thermal-mechanical loading near the intersection. To address this issue, the present work develops an algorithm in Abaqus to use the seam crack capability and Paris law to efficiently perform iterative crack growth simulations. This approach captures the uneven growth response of the crack, providing more realistic service life estimations.