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Structural Integrity Assessment Of Shell And Tube Heat Exchanger Tube-To-Tubesheet Joints Fabricated Using Conventional And Nonconventional Manufacturing Processes, Dinu Thomas Thekkuden

Dissertations

Tubes and tubesheets, integral components of shell and tube heat exchangers, have an important role in the functioning of the heat transfer between the tube-side and shell-side fluids. Tube-to-tubesheet joints act as a barrier to prevent the mixing of the transfer fluids in addition to aiding the structural rigidity of the shell and tube heat exchanger. Tube expansion process and welding are the manufacturing processes used for fabricating structurally rigid tube-to-tubesheet joints. Many instances of tube-totubesheet joint failures leading to the complete collapse of the heat exchangers demand attention to assessing the mechanical and metallurgical characteristics of tube-totubesheet joints fabricated …

Capturing Maximum Photovoltaic Power With Machine Learning: Maximum Current Prediction, Mppt Methodology, And Adjustable Ml-Based Controller, Zahi Mohamed Mohamed

Dissertations

The primary aim of this doctoral thesis is to examine the potential application of machine learning (ML) in optimizing Maximum Power Point Tracking (MPPT) and devising a flexible ML-based controller for photovoltaic (PV) systems. The lack of MPPT mechanisms leads to fixed voltage and current points for PV modules, resulting in substantial power loss when environmental conditions vary. The limitations of conventional and enhanced MPPT methods, as well as finding an alternative controller to classical Proportional-Integral (PI) controllers, have spurred the search for substitute approaches to maximize PV power. To address these limitations, this thesis proposes using ensemble ML techniques, …

Maternal Vitamin B12 And D Status, Depression, And Dietary Intake And Neonatal Outcomes Following Bariatric Surgery, Amna Salem Al Mansoori

Dissertations

Bariatric surgery is a more effective approach than dieting for women with morbid obesity and can reduce comorbidities, such as hypertension and gestational diabetes, while improving fertility. Vitamins B₁₂ and D have essential roles in ensuring a healthy pregnancy and favorable neonatal outcomes. However, pregnancies following bariatric surgery may be complicated by micronutrient deficiencies, particularly of vitamins B₁₂ and D. This study aims to investigate vitamin B₁₂ and D status and neonatal outcomes in pregnant women who underwent sleeve gastrectomy or Roux-en-Y gastric bypass compared with those of women who did not. Additionally, the dietary intake and …

Development Of Innovative Multi-Drug Approaches To Counteract Illicit Drug Abuse In The Uae Population, Manal Ali Alhefeiti

Dissertations

The abuse of addictive substances is on the rise in the United Arab Emirates (UAE) population. Consequently, the UAE government spends about Dhs 5.5 billion annually on the rehabilitation of drug addicts. Blood, urine, and hair tests can reveal signs of sporadic or chronic drug use. Given the list of banned chemicals in the UAE, our main objective in this work was to develop a novel analytical method to identify and measure banned substances, especially prescription and over-the-counter drugs in the UAE. We developed and validated a rapid, sensitive and reliable liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) approach for the targeted …

Celiac Disease Prevalence And The Characteristics Of Celiac Patients In The United Arab Emirates, Two Centers Study, Asma Hamed Alnababteh

Dissertations

Celiac Disease (CD) is a chronic autoimmune gastrointestinal disorder caused by genetic susceptibility to gluten and affects around 1% of the population worldwide. CD can occur at any age and is diagnosed by detecting specific serological biomarkers and histopathological changes in the duodenal biopsy. In the United Arab Emirates, there is a lack of studies describing CD in children or adults; this thesis aimed at researching the epidemiology of celiac disease in among the populations in the United Arab Emirates.

Two Studies were conducted to achieve the research objectives, study one was conducted in Cleveland Clinic Abu Dhabi (CCAD) and …

Nano-Supported Biocatalysts For Efficient Wastewater Remediation, Khadega Abobaker Al-Maqdi

Dissertations

The existence of various bioactive organic pollutants in wastewater and municipal water sources has raised concerns regarding their potential effects on human health. As a result, different techniques are being explored to effectively break down these persistent organic pollutants. Peroxidases have recently emerged as a new approach to remediation that may have advantages over traditional methods. However, evaluating the effectiveness of different peroxidases in breaking down various emerging pollutants can be time-consuming and difficult. In this study, a quick and reliable method was developed to test the degradability of 21 emerging pollutants by five different peroxidases (soybean peroxidase, chloroperoxidase, lactoperoxidase, …

Factors Affecting Changes In Road Traffic Collision Related Injuries And Deaths Over Time: The Global And The United Arab Emirates Perspectives, Yasin Jemal Yasin

Dissertations

Road traffic collisions (RTCs) cause 1.35 million deaths per year worldwide. Approximately 50% of these deaths were among pedestrians and motorized 2-3-wheeler users. In the United Arab Emirates (UAE), RTC deaths were higher compared to other high-income countries (HICs). The United Nations (UN) Decade of Action for road safety 2011-2020, aimed to reduce road traffic deaths by 50% by the year 2020. The aim of this dissertation was to investigate factors affecting changes in RTC-related injuries and deaths over time at global and UAE levels. Multiple research methods were used to investigate the research questions. Global data on pedestrian and …

Ab-Initio Investigation Of 2d Materials For Gas Sensing, Energy Storage And Spintronic Applications, Saba Khan

Dissertations

The field of Two Dimensional (2D) materials has been extensively studied since their discovery in 2004, owing to their remarkable combination of properties. My thesis focuses on exploring novel 2D materials such as Graphene Nanoribbon (GNR), holey carbon nitride C₂N, and MXenes for energy storage, gas sensing, and spintronic applications, utilizing state-of-the-art techniques that combine Density Functional Theory (DFT) and Non-Equilibrium Greens Functions (NEGF) formalism; namely Vienna Ab-initio Simulation Package (VASP) and Atomistic Toolkit (ATK) package.
/="/">Firstly, on the side of gas sensing, the burning of fossil fuels raises the level of toxic gas and contributes to …

Characterization And Genomic Analysis Of Two Escherichia Coli O157:H7 Bacteriophages Isolated From Pigeons, Mohamad I. Alolama

Dissertations

Enterohemorrhagic Escherichia coli, also known as EHEC, is a subset of Shiga toxin-producing E. coli (STEC), and it has recently been identified as one of the principal foodborne pathogens. E. coli O157:H7 is the most important serotype of STEC for its role in causing foodborne illnesses. E. coli O157:H7 could cause various gastroenteritis symptoms such as diarrhea, hemolytic uremic syndrome, hemorrhagic colitis, and thrombotic thrombocytopenic purpura and may cause death. Elimination of E. coli O157:H7 during food processing and storage is a possible solution. Bacteriophages have a significant impact on bacterial populations in nature due to their ability to …

Integrated Experimental And Dft Study Of Palladium And Nickel Metals Supported On Reducible Metallic Oxides For Selective Hydrogenation Of Alkynes And Dienes Bonds, Toyin Daniel Shittu

Dissertations

This dissertation investigates the capacity of ceria (CeO₂) to serve as a stand-alone reactive catalyst, and to act as catalyst support for different catalyst configurations. Experimental and density functional theory (DFT) approach were used to critically predict and to design ceria-containing catalysts. Ceria owes the catalytic propensity to the ability to undergo switch in the oxidation state from the +4 to +3 states. Motivated by experimental studies involving CeO₂ catalysts, defects CeO₂ surface with an oxygen vacancy (CeO2(111)_Vo) was used to explore the decomposition chemistry of methanethiol based on DFT. The potential formation pathways revealed that …

Prevalence Of Metabolic Syndrome And It’S Associated Factors In Emirati Adults: The Uae Healthy Future Cohort Study, Shamma Jauaan Almuhairi

Dissertations

In the last few years United Arab Emirates showed a rapid growth in economic field which was associated with growth of other types of related diseases, specially in non-communicable disease; mainly type 2 Diabetes Mellitus (DM) & cardiovascular related diseases (CVDs). The presence of multiple risk factors simultaneously in Metabolic Syndrome (MetS) has been shown to increase the risk for atherosclerosis development in young and middle-aged adults. Metabolic syndrome (MetS) is clustering of cardiometabolic risk factors and has many different definitions according to different international organizations. Aims and objectives:This study has three main objectives; it aimed to estimate the prevalence …

Impact Of Teaching Mathematics With Four Teaching Strategies On Fifth Grade Students’ Learning Of Fractions Addition And Subtraction, Nabil Riziq Al Farra

Dissertations

There are different tools, resources, and materials that mathematics teachers may use to enhance the teaching and learning processes under many types of teaching strategies such as technology (e.g., videos and virtual manipulatives), real objects (e.g., concrete manipulatives), and other teaching strategies are traditional (e.g., lectures). Some of the most important things that a teacher has to consider is the students’ learning needs and how to reach to their minds by different teaching strategies with a variety of resources and assess which are more effective in students’ learning anddevelopment in mathematics.

The purpose of this study is to investigate the …

Approximate Computing Based Processing Of Mea Signals On Fpga, Mohammad Emad Hassan

Dissertations

The Microelectrode Array (MEA) is a collection of parallel electrodes that may measure the extracellular potential of nearby neurons. It is a crucial tool in neuroscience for researching the structure, operation, and behavior of neural networks. Using sophisticated signal processing techniques and architectural templates, the task of processing and evaluating the data streams obtained from MEAs is a computationally demanding one that needs time and parallel processing.
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/="/">This thesis proposes enhancing the capability of MEA signal processing systems by using approximate computing-based algorithms. These algorithms can be implemented in systems that process parallel MEA channels using the Field …

Lax Integrability And Solution Methods For The Nonlinear Schrödinger Equation With External Potentials: Exact Solutions And Applications, Laila Yahya Al Sakkaf

Dissertations

The investigation of a nonlinear differential equation (NLDE) integrability is the foundation for understanding and predicting the behavior of systems that are governed by that NLDE. The existence of a Lax pair (LP) representation is a reliable indicator of the indicator of the integrability of an NLDE. If an NLDE admits an LP, it is considered integrable in the LP sense, and this has important implications for the behavior and solutions of the system. The LP plays a crucial role in many powerful analytical solution methods for solving NLDEs. One such method is the Darboux transformation (DT), which allows for …

Optimal Component Sizing And Control Of A Multi-Source Elecctric Vehicle Based On An Improved Optimization Algorithm And A Novel Energy Management System, Prasanthi Achikkulath

Dissertations

Electric vehicles (EVs) are considered the ultimate solution for a sustainable transportation alternative to reduce the global warming and energy crisis. The public's perception of EVs is still adverse despite advancements in EV technology because of issues with driving range, high initial costs, the added weight of the energy source, and an unpredictably short lifespan of the EV system. To administer the same performance as compared to modern fossil fuel-based vehicles, hybridization of multiple energy sources is significant for EVs. The most pressing issues with multi-source EVs are optimum source sizing and regulating power flow from hybridization sources with the …

Community College Students’ Awareness Of Their Reading And Writing Proficiency, Martha Paulina Campusano Rojas

Dissertations

Student’s low reading and writing proficiency in higher education has been the subject of a large body of research (e.g., Bahr, 2011; Bailey, 2010; Carlino, 2005, 2010, 2012; Flink, 2017; Jaggars, 2014 Pacello, 2014; Perin, 2011; Perin et al., 2013).The purpose of this qualitative study was to explore how students in a first-year developmental Spanish course at the Dominican community college think of the connection between their reading and writing abilities and their performance in both their current and future undergraduate courses. The study also explored how these students view the importance of the developmental course and how they understand …

Statistical Clustering Of Networks With Additional Information, Paul Atandoh

Dissertations

As the online market grows rapidly, many companies and researchers are interested in analyzing product review dataset which includes ratings and text review data. In the first project, we mainly focus on analyzing the text review data. In the current literature, it is common to use only text analysis tools to analyze review dataset. But in our work, we propose a method that utilizes both a text analysis method such as topic modeling and a statistical network model to build network among individuals and find interesting communities. We introduce a promising framework that incorporates topic modeling technique to define the …

Using Visual Imagery To Develop Multiplication Fact Strategies, Gina Kling

Dissertations

The learning of basic facts, or the sums and products of numbers 0–10 and their related differences and quotients, has always been a high priority for elementary school teachers. While memorization of basic facts has been a hallmark of elementary school, current recommendations focus on a more nuanced development of fluency with these facts. Fluency is characterized by the ability to demonstrate flexibility, accuracy, efficiency, and appropriate strategy use. Despite recommendations to focus on strategy use, there is insufficient information on instructional approaches that are effective for developing strategies, particularly for multiplication facts. Using visual imagery with dot patterns has …

Experiences Of Counselors Who Assist Women In Midlife Who Display Depressive Symptoms: A Transcendental Phenomenological Study, Carla Tovar

Dissertations

In this dissertation, I present a transcendental phenomenological study conducted with 12 counselors who worked with women in midlife who displayed depressive symptoms. The purpose of this study was to understand the lived experiences, clinical and personal, of licensed professional counselors (LPCs) who worked with women in midlife who displayed depressive symptoms. Through the study, I sought to recognize the essence and themes that emerged from these LPCs who worked with this population. Moreover, this study was designed to obtain a better understanding of how these LPCs managed their feelings and thoughts, how they helped when working with these women, …

An Autoethnographic Journey To Critical Consciousness: How A White Faculty Member At A Hispanic Serving Institution Moves From Ally To Accomplice By Learning Student Struggles, Benjamin Mercer Drury

Dissertations

This study serves to document my transition into critical consciousness – or conscientização – through interactions with my students. I utilize narrative autoethnographic methods, content analysis, qualitative interviewing, and personal reflection to document my transformation from objectively interested faculty member to accomplice by learning about how the life of my students outside of school affected their performance inside of school. Significant findings fall into two categories: personal and professional. Personally, this study was cathartic. By using a scholarly lens to analyze and reflect on my experience, I was able to process my experience in the context of existing research and …

How Prepared Are Educators To Work With Students Of Color, Ja're Thorn

Dissertations

From what I have experienced, there has been a lack of preparation when it comes to preparing educators to work with students of color. This research aimed to explore the importance of early childhood teachers’ cultural preparation programs when it comes to working effectively with students of color. Most of the time, teachers teach to the common core standards set in place by the state. They also implement a curriculum that is considered “best practices” for students instead of paying attention to and considering the individual student’s specific culture, family, and community values and ways of life before planning (Spies, …

Exploring The Use Of Cultural Values In The Evaluation Of Programs With Native American Tribes, Karen Lynn Alexander

Dissertations

This dissertation is a qualitative study that explores the importance of including cultural values in evaluation and whether this would lead to an increase in utilization of evaluation results. It was first wondered whether Native American values are included when evaluations are completed for Indigenous Tribes. A review of evaluations revealed that evaluations in the published literature are including general Native American values, although a document review alone was found to be insufficient as a method to capture the nuances related to value expression. It is suggested that more research is needed in the area of metaevaluation to include culturally …

Assessing And Characterizing Marijuana Use Disorders (Dsm-5) — National Survey On Drug Use And Health, United States, 2020, Alejandro Azofeifa-Ujueta

Dissertations

Despite that marijuana (cannabis) is still considered, under federal law, an illegal Schedule I drug, marijuana is the most commonly used illicit substance in the United States. National trend data has shown that the prevalence of marijuana use has increased over time, particularly among those aged 18 years and older. Some individuals can use marijuana without harm; however, long-term and heavy marijuana users may experience health consequences, including marijuana use disorders (addiction). For the last 20 years, existing national and statelevel epidemiological, surveillance, and research data have analyzed marijuana use disorders (MUD) using previous diagnostic criteria (DSM-IV). There is limited …

Zonality In Graphs, Andrew Bowling

Dissertations

Graph labeling and coloring are among the most popular areas of graph theory due to both the mathematical beauty of these subjects as well as their fascinating applications. While the topic of labeling vertices and edges of graphs has existed for over a century, it was not until 1966 when Alexander Rosa introduced a labeling, later called a graceful labeling, that brought the area of graph labeling to the forefront in graph theory. The subject of graph colorings, on the other hand, goes back to 1852 when the young British mathematician Francis Guthrie observed that the countries in a map …

High-Dimensional Variable Selection Via Knockoffs Using Gradient Boosting, Amr Essam Mohamed

Dissertations

As data continue to grow rapidly in size and complexity, efficient and effective statistical methods are needed to detect the important variables/features. Variable selection is one of the most crucial problems in statistical applications. This problem arises when one wants to model the relationship between the response and the predictors. The goal is to reduce the number of variables to a minimal set of explanatory variables that are truly associated with the response of interest to improve the model accuracy. Effectively choosing the true influential variables and controlling the False Discovery Rate (FDR) without sacrificing power has been a challenge …

Irregular Domination In Graphs, Caryn Mays

Dissertations

Domination in graphs has been a popular area of study due in large degree to its applications to modern society as well as the mathematical beauty of the topic. While this area evidently began with the work of Claude Berge in 1958 and Oystein Ore in 1962, domination did not become an active area of research until 1977 with the appearance of a survey paper by Ernest Cockayne and Stephen Hedetniemi. Since then, a large number of variations of domination have surfaced and provided numerous applications to different areas of science and real-life problems. Among these variations are domination parameters …

Research Training And Certification Protocol For Medical Students, Michelle Arisleida Padley

Dissertations

Early and frequent exposure to research is imperative to initiating and sustaining long term for medical student research interest. The attitude and approach of physician mentors has been demonstrated to have a substantial effect on student perceptions of research involvement. The purpose of this study is to determine best practices for assessing student perceptions for a research certification program. An additional long-term objective is to utilize these findings to help maintain interest in research throughout their medical careers. Research is an essential aspect of the prestige of medical schools, and the benefits of academic research institutions have numerous facets, including …

A Critical Analysis Of Discrepancies In Behavioral Health Program Ratings By Evidence-Based Practice Registers For Behavioral Health, Miranda Jade Lee-Easton

Dissertations

Decision makers in the behavioral health disciplines are under increasing pressure to identify and implement evidence-based practices (EBPs). These decision makers often do not have the time or expertise to assess primary studies of program efficacy or effectiveness. They could benefit from tools to assist them in identifying and implementing EBPs. One tool is an evidence-based practice register (EBPR). Prior studies have documented that when multiple EBPRs rate a given program, they may come to seemingly conflicting program ratings. The prior research concerning the reason for these conflicts is sparse. The purpose of the present study is to understand how …

Development Of Modeling Tools To Determine The Effects Of Customer Diversification On Customer Lifetime Value Volatility In Higher Education, Oscar Neal

Dissertations

As societies become increasingly global the competition for customers continues to increase. In competitive markets, it is important to identify a process to acquire and retain the most profitable customers. To discriminate customers, it is important to understand the value different customers bring to an organization. Much research has been done modeling customer value using customer lifetime value, however, there is limited research on the effect current customer diversity has on future customer lifetime value of future customer portfolios.

In this dissertation, a Lifetime Value Model considering the interaction between customer diversity, revenue management, and customer lifetime value in an …

Teaching And Assessing Cornhole As A Leisure Activity For Young Adults With Developmental Disabilities, Katarina Rotta

Dissertations

Leisure has long been identified as a crucial component of a healthy lifestyle. One population that displays extremely low levels of leisure activity is people with developmental disabilities, which is concerning because previous research has identified a positive correlation between leisure activity and quality of life among such individuals. The purpose of the present project was to teach and assess cornhole as a leisure activity for seven young adults with developmental disabilities. Study 1 assessed points scored with four versions of cornhole and preference for those versions. Study 2 evaluated a procedure intended to teach participants to keep score. A …