Digital Commons Network^™

Application Of A New Scale-Resolving Turbulence Model To Supersonic Retropropulsion Flows With Chemistry, Gabriel C. Nastac

Dissertations

Turbulent compressible flows are ubiquitous in many engineering applications of flight and propulsion. Computational fluid dynamics simulations are commonly performed to analyze these flows. Scale-resolving turbulence models inherently better capture various flow phenomena, including separation and mixing, as well as enable predictions of fluctuations, which can be critical for design compared to traditional steady-state turbulence models. In this work, new scale-resolving blended Partially-Averaged Navier-Stokes (BPANS) turbulence models are developed to account for compressibility effects and are employed to efficiently simulate turbulent compressible flows. Specifically, supersonic retropropulsion flows are investigated. Supersonic retropropulsion is a key technology for next-generation rockets. The new …

Examining Systemic And Dispositional Factors Impacting Historically Disenfranchised Schools Across North Carolina, Raketa Ouedraogo-Thomas

Dissertations

This mixed method sequential explanatory study provided analysis of North Carolina (NC) school leaders’ dispositions in eliminating opportunity gaps, outlined in NC’s strategic plan. The study’s quantitative phase used descriptive and correlation analysis of eight Likert subscales around four tenets of transformative leadership (Shields, 2011) and aspects of critical race theory (Bell, 1992; Ladson-Billings, 1998; Ladson-Billings & Tate, 2006) to understand systemic inequities and leadership attitudes.

The qualitative phase comprised three analyses of education leadership dispositions and systemic factors in NC schools. The first analysis of State Board of Education meeting minutes from 2018–2023 quantified and analyzed utterances of racism …

“A Real Man . . .”: Deconstructing Machismo Heteronormative Standards With K–12 Latino Male Educators Through Dialogic Spaces, Mario Echeverria

Dissertations

In a K–12 educational landscape where 75% of educators are white women, recruitment of Latino male educators is crucial for diversification, yet these educators represent just 2% of the teaching workforce in the United States (NCES, 2020). These educators grapple with a layered sense of identity as they navigate expectations of hegemonic masculinity and machismo norms that dictate their roles as disciplinarians and saviors, especially for young boys of color (Brockenbrough, 2018; Lara & Fránquiz, 2015; Martino & Kehler, 2006; Mills et al., 2004; Singh, 2021). Unfortunately, Latino male educators leave the profession at twice the rate of their Latina …

(Miss)Educated Latino Males: Academic Preparedness, Navigation, And Retention At 2-Year Colleges, Nannette Stephanie Regua

Dissertations

This study centers Latino males, first generation, first year students at four 2-year colleges in the Silicon Valley by understanding their experiences in transferable English 1A Writing Composition course and looking at the acts of instilling a sense of belonging and mattering by institutional agents and support services that are invaluable to student retention and success. The purpose of this study is to determine Latino male students’ perceptions of academic preparation, navigation, and success in higher education after the implementation of California Assembly Bill 705. My findings revealed important themes that map onto conceptual frameworks, most notably the Community Cultural …

Addressing Equity Gaps In Stem: A Self-Study, Prabhjeet Kaur Brar

Dissertations

The Hispanic/Latinx population is increasing nationwide and in the state of California; however, the Hispanic/Latinx population remains underrepresented in STEM professions contributing to a lack of diversity in STEM. To increase the academic success of the Hispanic/Latinx student population in STEM majors, high leverage research-based teaching strategies through the lens of historically responsive literacy were applied and examined throughout this research. The purpose of this mixed-methods self-study was to examine the impact of research-based effective strategies/high leverage practices on Latinx students’ success rates in my introductory biology classrooms. The study focused on two biology course sections with a laboratory. Each …

Exploring Manifestations Of Pluriform Love In The Leadership Of Christian Early Childhood Communities: A Phenomenological Study 2019-2024 In New Zealand, Sharon Kaye Judge

Dissertations

Problem

This study responds to the need to explore and/or propose models of leadership for Christian early childhood education and care (ECEC) settings in New Zealand (NZ). While previous studies identify love and care as a priority there is a need to define and prioritize Biblical understandings of love that may align with the principles of the national ECE framework. The study represents an alternative narrative to the neo-liberal influences which dominate areas of ECEC leadership through the marketization and standardization of children’s services nationally and globally.

Purpose of Study

Many factors contribute to the purpose of this study which …

Employees' Perception Of The Management Of The Covid-19 Crisis At Najran University, Saudi Arabia, Noora Nasser Alsuhaibani

Dissertations

Problem

During the COVID-19 crisis, particularly in the context of Saudi education, the ability to physically attend schools and colleges was greatly hindered due to the widespread transmission of the virus and the resulting obstacles. The issues necessitated the use of crisis management strategies. Some Saudi universities are capable of implementing an organized plan both before to and during crisis management, whereas others lack this competence. This is a substantial problem. Several universities in Saudi Arabia effectively managed the COVID-19 epidemic, whereas others did not. Furthermore, prior studies on crisis management indicate that administrators exhibit diverse responses. By participating in …

Reporting And Addressing Sexual Harassment At Four Institutions Of Higher Learning In Zambia: A Quantitative Study Of Related Attitudes And Perceptions, Earlymay Chibende

Dissertations

Problem

Sexual harassment is a social ill that exists across nations, socio-economic backgrounds, races, nationality, ethnicity, age groups, and sex. Although both male and female members of society experience sexual harassment, research shows that a greater percentage of sexual harassment victims are women (Whitley & Page, 2015; CharterJee, 2018). A comparison of the prevalence of sexual harassment at workplaces and educational institutions shows that sexual harassment is more widespread at institutions of learning than at workplaces. Research on the prevalence of attitudes and or perceptions toward sexual harassment in institutions of higher learning shows that between 10%- 68% of female …

The Impact Of Hybrid Working On Employee Way Of Life And The Need To Reshape The Employee Value Proposition, Kanishka Chandanamali Athalage

Dissertations

This dissertation details a post-pandemic qualitative investigation conducted to understand the impact of hybrid working solutions on reshaping the employee value proposition (EVP) in the health insurance industry of the UAE. The research aims to evaluate how the introduction of modern hybrid working solutions impacts employees in a post-pandemic environment and, in turn, whether this creates a demand for human resources to refocus drivers of the EVP. Traditionally, EVP is referred to as the overall give-and-get in an employment deal; however, the pandemic was an eye-opener for organizations to redefine what it entails. Since hybrid working has become the new …

Shocks And Cold Fronts In Merging Galaxy Clusters, Purva Diwanji

Dissertations

Galaxy clusters, found at the nodes of the large-scale structures in the universe, are the most massive gravitationally bound and virialized structures in the Universe. They are formed via accretion, gravitational infall, and hierarchical mergers of smaller sub-clusters and galaxy groups. Mergers of galaxy clusters are the most energetic events in the Universe after the Big Bang, wherein the sub-clusters collide at velocities of ~1000km/s, releasing energy of the order of 10^(64) ergs. During such a merger, the galaxies and dark matter of both clusters interact only gravitationally and move unhindered through the region of the collision. This dissertation presents …

Characterization Of Size Effects In Additively Manufactured Grcop-42 And Their Influence On Mechanical Response, Gabriel Demeneghi

Dissertations

This study investigates size effects on microstructure, mechanical behavior, and fatigue performance of additively manufactured GRCop-42. Systematic analyses, encompassing changes on powder composition, wall thickness, and heat treatment, was conducted on specimens produced through laser powder bed fusion (L-PBF) and laser powder direct energy deposition (DED) techniques. L-PBF specimens exhibited a reduction in strength and elongation with decreasing thickness, attributed to increasing porosity as specimen’s thickness decreases. Conversely, in DED specimens, decreasing mechanical properties with thickness were associated to surface topography. Emphasizing the non-generalizability of size effects across AM methods. Size effects were also investigated on high cycle fatigue, as …

Assembly And Analysis Of Space Biofilm-Forming Bacterial Model Organisms Towards The Treatment Of Water System Biofilms, Yo-Ann VéLez Justiniano

Dissertations

Space exploration imposes unique challenges on the human body and engineered systems alike. One such challenge is the control of microbial life, specifically biofilms, within the water processor assembly of the International Space Station (ISS). This investigation aimed to determine the feasibility of using an innovative bioremediation approach to mitigate biofilm growth in the water processor assembly. This approach entails the dissemination of a desired anti-biofilm gene across the microbial population of the water processor assembly through horizontal gene transfer via conjugation. To ascertain the viability of this method, the research was divided into two primary focuses. The first part …

Coronal Magnetic Field Extrapolation And Topological Analysis Of Multi-Scale Magnetic Structures For Solar Eruptions, Wen He

Dissertations

Solar eruptions are manifestations of strong solar activities which occur in multiple scales and vary significantly in observations. It has also been increasingly realized that some scenarios initially proposed for relatively large-scale eruptions may persist down to much smaller/finer scales, largely owing to increasingly high-resolution observations of the Sun. However, confirming the coherent magnetic structures on the Sun remains challenging due to the lack of direct coronal magnetic field measurement. This dissertation mainly focuses on the topological analysis of multi-scale magnetic structures embodied in different solar eruptions with available observations. It is achieved by reconstructing the 3D coronal magnetic field …

The Structural Basis Of Inflammation : Computational Characterization Of Molecular Mechanisms, Sara W. Jackson

Dissertations

Computational tools are useful in the interpretation and analysis of experimental data. In the world of structural biophysics, computational tools go a bit further: they can simulate atomic motions and molecular interactions based on experimentally-determined biomolecule structures, therein describing natural phenomena, and inspiring the formulation of new hypotheses. In this work, computational structural biology tools are used to answer questions about molecules of inflammatory importance. Quantum chemistry computational tools are used to determine the electronic structure of sesamin, a component of many diets which may be a modulator of an enzyme involved in the metabolism of inflammation mediators. Virtual docking …

Mitigation Of Inflammation In Early Post-Traumatic Osteoarthritis Through Low-Intensity Ultrasound, Shahid Khan

Dissertations

Post-traumatic osteoarthritis (PTOA), a subset of OA caused by direct injury or repetitive microtrauma, results in a robust release of inflammatory mediators. If inadequately controlled, this pro-inflammatory phase leads to early tissue damage. The biomedical burden of PTOA is significant and inadequately addressed due to difficulties in identifying the disease onset, slow progression, and incomplete understanding of its etiology and pathogenesis. However, PTOA's distinct initiating events allow for early intervention. This thesis investigates whether fibronectin fragments (FnFs) can induce an early inflammatory response in a triple cellular in vitro model of early PTOA and whether continuous low-intensity ultrasound (cLIUS) can …

Understanding Battery Degradation And Failure With Impedance And Imaging Techniques, Megan F. Gober

Dissertations

With the increasing desire for fast charging capabilities in lithium-ion batteries due to the popularity of electric vehicles, research has recently been focused on increasing energy and power density while simultaneously revealing the need for improved understanding of degradation mechanisms to achieve the desired safety and fast charge performance. The work presented seeks to further understanding of mechanical, temperature, and electrochemical degradation mechanisms within varying battery chemistries and geometries through evaluation of impedance response and multiscale imaging techniques. First, in order to understand the limitations of mechanical and electrical integrity of battery systems, a combined application of impedance characterization and …

Nonlinear Dynamics Of Acoustic Fluctuations In One-Dimensional Ducts With And Without Unsteady Combustion, Swarnalatha Kathalagiri Vasantha Kumar

Dissertations

The overall objective of this research is to analyze the nonlinear dynamics of combustors in one dimensional Cartesian coordinate. This research was carried out in four parts, with each successive part building on the previous one. The first part begins with investigation of the coupled nonlinear evolution of acoustic modes in a quasi 1-D duct with axially inhomogeneous mean velocity and mean thermodynamic properties. A novel modification of the Krylov--Bogoliubov method of averaging (KBMA) is developed to analytically solve the modal-amplitude equations that are linearly and nonlinearly coupled with both quadratic and cubic nonlinearities. Approximate analytical solutions based on the …

The Role Of Surface Processes In Modulating Land-Sea Breeze Circulation : An Observational And Numerical Modeling Study In Java, Georgios Priftis

Dissertations

In the Maritime Continent (MC), sea and land breezes (SLB), shaped by its numerous islands, are key drivers of the tropical climate. Island morphology, terrain, land cover, and orientation relative to prevailing winds affect these breezes and associated convection. While research has largely focused on larger islands, smaller islands like Java remain understudied. Java features a mountainous chain with several gaps and experienced significant land use and land cover changes (∆LULC) over the past two decades. This dissertation aims to: 1) adapt observational methods to detect mesoscale boundaries in numerical models, 2) analyze the role of Java’s topography and cloud- …

Nuclear Fission Rovers For Martian Exploration, Alexander Constantine Bendoyro

Dissertations

A comprehensive analysis was performed on the impact of embedding a Kilopower-style fission reactor into a pressurized rover on architectural performance for a sample lunar, Mars opposition, and Mars conjunction mission. The high gamma ray flux necessitated the addition of substantial shielding for the crew. A single material shielding analysis using the Taylor formulation revealed that varying the distance between the crew and the reactor core from 3 m to 6 m reduced the required shielding thickness by 7%. Increasing the power output of the reactor from 3.4 kWe (comparable to radioisotope power capability) up to 10 kWe (Kilopower design …

Novel Photobase Generators For Photoinduced Polymerization And Ph Regulation, Shupei Yu

Dissertations

Photochemistry encompasses the investigation of chemical processes instigated by light absorption. As important branches of photochemistry, photosensitive and optical materials have attracted extensive research interests in both academia and industry. Photosensitive and optical materials are composed of polymers / small molecules with photo-responsive properties. These materials not only can absorb light in the desired energy spectrum, but also exhibit chemical / physical reactions, which can be applied to different fields such as photoredox, photo-heat, phototherapy, solar cells, diodes, etc. Among them, photobase generators (PBGs) are a series of photosensitive compounds, which absorb the incident light, then release the basic species …

Establishing A Novel Lipid-Polyamine Metabolic Connection To Virus Replication, Yazmin Edith Cruz Pulido

Dissertations

Polyamines are small positively charged alkylamines found in all living cells. These ubiquitous molecules have been found to play a variety of roles ranging from stabilizing nucleic acids (DNA and RNA) to cellular proliferation. Studies have also identified roles for polyamines in viral packaging and viral enzyme function. However, the role of polyamines on cellular components and their effect on viral replication is less known. In our efforts to identify the lipid-polyamine metabolic connection to virus replication we utilized a human hepatocyte cell line in which polyamines were depleted via pharmacological or genetic approaches and studied the effects on lipid …

Relationship Between School-Wide Positive Behavior Interventions And Supports, Student Achievement, And Teacher Efficacy In High Poverty Rural Alabama Elementary Schools, William Combs

Dissertations

The purpose of this research study is to determine if relationships exist between the level of School-wide Positive Behavior Interventions and Supports implementation, student academic achievement, and teacher self-efficacy in high-poverty rural Alabama elementary schools. The research encompassed a comprehensive analysis of existing literature, incorporating historical and policy-related context, theoretical underpinnings, relevant studies, and expert viewpoints. Additionally, the research involved the gathering and examination of data, presentation of findings, establishment of conclusions, and suggestions for prospective research directions. The primary objective of this study is to investigate potential correlations between the extent of SWPBIS (School-Wide Positive Behavior Interventions and Supports) …

Arturo Rodriguez: A Mexican Mosaic. A Discussion Of His Life And Selected Works, Jorge Gonzalez

Dissertations

Arturo Rodríguez (b. 1976) is a Mexican composer living in Los Angeles, California. His music has gained tremendous popularity in México within the last ten years and is being performed regularly by some of the most prestigious professional orchestras in México and abroad. One of the most interesting aspects of his career is that he writes music for both the concert hall and motion pictures. His compositional output is abundant and covers a variety of genres including music for symphony orchestra, chamber orchestra, chamber music, and piano. Rodríguez has focused on the art of symphonic composition for the past fifteen …

Heterotypic Interaction Of Α-Synuclein And Tdp-43 In Neurodegenerative Diseases, Shailendra Dhakal

Dissertations

Amyloid aggregates of specific proteins form important pathological hallmarks in many neurodegenerative diseases, defining neuronal degeneration and disease onset. Recently, increasing numbers of patients show co-morbidities and exhibit clinical and pathological overlaps between multiple neurodegenerative diseases including α-synucleinopathies and TDP-43 proteinopathies. These overlaps are often accompanied by co-localization of α-synuclein (αS) and TDP-43 enhancing the possibility of direct interactions to generate heterotypic amyloids with distinct cellular consequences. To understand this, we investigate the interaction of α-synuclein (αS) and prion-like domain of TDP-43 (TDP-43 PrLD) in both homogenous and inhomogeneous phases. Firstly, we show that monomeric TDP-43 PrLD and αS interact …

An Examination Of Influential Factors Of Academic Dishonesty And Ethical Decision-Making Among Community College Nursing Students, Roshelle L. Lemon-Howard

Dissertations

Academic dishonesty remains a pervasive, multi-discipline dilemma which has been reported as having the propensity of resulting in longstanding consequences beyond academic settings. Previous research has suggested that students who participate in dishonest behaviors while attending institutions of higher education have greater tendencies to engage in dishonest and unethical behaviors within professional settings. Notably, schools of nursing are not exempt from academic dishonesty and the ramifications that have been associated with such misconduct. Although academic dishonesty has been examined from various perspectives, and in numerous contexts, current studies that compare relationships between peer and faculty influences on academic dishonesty and …

Structural Features Of Hiv-1 Integrase In The Late Stage Of Viral Replication, Tolga Catmakas

Dissertations

HIV-1 integrase (IN) is an essential enzyme for the viral life cycle as it integrates viral genomic material into the host cell genome. In addition to its’ essential catalytic function, IN has another important non-catalytic role where it binds the viral RNA to facilitate successful particle maturation during the viral life cycle. A significant number of IN mutants, addressed as class II IN mutants, show various defects, affecting different steps of the viral life cycle. Class II IN mutants exhibit aberrant morphology where viral ribonucleoprotein particles are mislocalized outside of the capsid core. This phenomenon can be observed in the …

Coach-Athlete Conflict And Well-Being Outcomes For Division I Athletes, Alisha M. Hilliard

Dissertations

The purpose of the research was: to qualitatively explore and further understand NCAA Division I (DI) athletes’ experiences with coach conflict and the impact of that conflict on well-being. To serve the purpose of this research, the primary researcher used a purposive sample of DI student-athletes by contacting them directly or sharing the study with faculty, graduate students, and athletic department personnel who work with student-athletes. An interpretive phenomenological approach was utilized while engaging in qualitative inquiry to pursue richer answers to the research question, because these approaches “seek to explore, describe, and analyze the meaning of individual lived experience” …

Adaptive Leadership During Times Of Great Change And Opportunity, Danielle Daubin

Dissertations

Purpose: The purpose of this exploratory phenomenological study was to identify and describe the strategies used by middle school principals to build an adaptive capacity based on the five key characteristics of adaptive leadership identified by Heifetz et al. (2009).

Methodology: Three counties in northern California were selected to conduct a phenomenological study on middle school principals. Of this population, purposeful sampling was applied to identify participants who met specific criteria. Ten participants were selected: four from Contra Costa County, three from San Joaquin County, and three from Stanislaus County. The researcher conducted one-on-one interviews to gather data, which was …

Power-Up With Emotional Intelligence: Exploring Flight Attendant Leadership And Crew Resource Management In A Dynamic Post-Pandemic Travel Environment, Carlin Laviolet Clarke

Dissertations

In the post-pandemic travel environment, disruptive passengers fail to accept flight attendants’ leadership and cause unruly incidents that compromise flight safety, damage airlines, and present behavioral challenges that can lead to physical harm (Al-Arshani, 2021; Albert, 2016; Araiza, 2022; Albert, 2016; FAA, 2021; Inspire Academy, n.d.-a.; International Air Transport Association [IATA], n.d.-b; James, 2022; Pederson et al., 2021; Ramona & Anbro, 2017; Timmis et al., 2018; TSA, 2021; Wong & Neustaedter, 2017). Flight attendants rely on Crew Resource Management (CRM) skills to manage inflight incidents; however, CRM promotes team effectiveness and flight attendants are often dispersed throughout the cabin and …

Employee Experiences With Leaders’ Influence On Autonomous Motivation: A Mixed Methods Study, Melissa Wheat

Dissertations

Organizational performance and success require employee motivation (Delaney & Royal, 2017; Devarapalli & Hinkes, 2016; Good et al., 2022; Howard et al., 2016; Mohamud et al., 2017; Olafsen et al., 2018; Ryan & Deci, 2017; Van den Broeck et al., 2021; Wiley, 1997). However, organizational leaders fail to effectively motivate employees to engage in the workplace and achieve high performance (Delaney & Royal, 2017; Fisher, 2009; Good et al., 2022; J. D. Jensen, 2018; Pappas, 2021; Webb, 2007; Workers Are Motivated by Different Drivers and Needs, 2022). This study explored employee experiences with leaders’ influence on autonomous motivation to …