Engineering Commons^™

Large-Scale Hpc-Empowered Power Electronics Modeling And Simulation In Photovoltaic Applications, Liwei Wang

All Dissertations

The rising popularity of renewable energy sources requires advanced, efficient power electronic systems for energy conversion, grid integration, and system management, thereby raising expectations for power electronics in the energy industry. The complexity of modern power electronic systems requires comprehensive simulations and in-depth analysis to predict performance accurately, but this process is impeded by prolonged simulation times. The primary objective of this dissertation is to develop a high-fidelity, high-speed event-driven simulator to tackle challenges related to mass data processing, uncertainty evaluation, as well as modeling and simulation issues in assessing the reliability of power electronics in large-scale Photovoltaic (PV) systems. …

Investigating Institutional Support For A Minority Engineering Program At A Historically White Institution, Stephanie Damas

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Engineering programs at historically White institutions (HWIs) often perpetuate stereotypes and racism against Black students, impacting their experiences and opportunities in the field. Minority engineering programs (MEPs) provide support and resources to minority students in engineering, challenging stereotypes and fostering positive identity development. MEPs push back on cultural norms by rejecting the stereotypical narrative of what it means to be Black in engineering. Despite their significance, MEPs face challenges in garnering institutional support and recognition within engineering departments. It is imperative to understand what institutional support for MEPs looks like to mitigate barriers identified in the literature. To address these …

Data-Driven Enhanced Energy Management System Applications For Energy Control Centers, Dulip Madurasinghe

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This dissertation explores the pressing needs of modern bulk power system operation and control and delves into enhancements to EMS applications with minimal infrastructure development. The dissertation investigates three main EMS application enhancements. The transmission network topology processing (TNTP) is a foundational application of the EMS. A physics-based hierarchical transmission network topology processing (H-TNTP), including substation configuration identification, to improve efficiency and reliability is proposed. Secondly, a multi-level distributed linear state estimation (D-LSE) approach solely based on PMUs is proposed utilizing H-TNTP as the network modeling tool. The D-LSE can conduct linear state estimation (LSE) at either substation, area or …

Ultra High-Performance Concrete As A High Friction Surface Treatment For Pavements And Bridges, Kyle Maeger

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High Friction Surface Treatment (HFST) is a proven technology to reduce crashes on roadways by increasing the coefficient of friction between vehicle tires and the pavement. However, it is an expensive solution due to the high cost of the two commonly used constituent materials, calcined bauxite aggregate and epoxy resin binders.

This study evaluated the abrasion resistance performance of four alternative HFST aggregates to calcined bauxite using Los Angeles Abrasion and Micro-Deval Abrasion tests, and studied the surface texture utilizing a high-resolution laser scanner and friction utilizing the British Pendulum Test.

This study also assessed the performance of non-proprietary Ultra …

Integrating Artificial Intelligence And Augmented Reality For Enhanced Task Performance In The Construction Industry, Aasish Chandrika Bhanu

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The Architecture, Engineering, and Construction (AEC) sector, characterized by its complex tasks, often faces challenges in adopting cutting-edge technologies, a trend that can significantly hinder productivity improvements compared to other industries. This dissertation explores the emerging integration of Artificial Intelligence (AI) and Augmented Reality (AR) within the AEC domain, investigating how effectively this can be implemented to potentially revolutionize industry practices. AI could be used in the AEC domain for advanced analytical and decision-making processes, while AR could be used for training, visualization, and remote collaboration.

In scenarios where construction site workers require expert guidance, these technologies could be helpful. …

Opioid Overdose Epidemic Modeling, Chelsea Spence

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The opioid overdose crisis in the United States has led to thousands of lost lives and thousands more people struggling with opioid dependence. Disease modeling allows researchers to examine the course that the disease may take and to investigate policies to determine the effects they may have. Disease models can be used to model non-communicable diseases and have been used to study opioid use disorder. Many types of disease models exist with their own inherent benefits and drawbacks.

In this dissertation, we provide a scoping review of the disease models that have been used to study the opioid overdose epidemic. …

Time-Domain Line Protection In Presence Of Renewables, Prabin Adhikari

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Inverter based resources (IBRs) are crucial in integrating renewable energy sources into the power grid. However, their unique fault characteristics, significantly different from synchronous generators (SGs), present several challenges for existing line protection schemes at both transmission and distribution levels. These schemes, reliant on distance and directional relays designed in phasor domain, are not well-suited for IBRs. Most published literature addressing this problem concentrates on altering the control design of inverters. However, this approach faces practical limitations. Inverter controls, often proprietary, are not readily accessible to utilities, rendering the control-based solutions impractical for widespread implementation.

To address this challenge, this …

Fluid-Solid Coupled Analysis Of Biological Samples In A Flow Chamber Using Optical Coherence Tomography, Reece W. Fratus

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Forces from fluid flow on a tissue or cellular boundary can drive remodeling processes through mechanotransduction pathways. In most cases, the exact mechanisms are not understood, such as in marine biofilm development or vascular remodeling. To gain a better understanding of these interactions, the flow profile at a solid boundary and the mechanical changes of that solid can be coupled together to determine the impact of fluid flow on mechanical remodeling. To achieve this, optical coherence tomography (OCT) is used to image the fluid and solid simultaneously. Fluid seeded with particles can be imaged and run through a particle image …

Fundamental Study Of Nonlinear Electrophoresis, Joseph Armakan Bentor

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Classical electrophoretic theory describes the linear response of particles suspended in Newtonian fluids under weak electric fields. When the electric field exceeds this weak limit, a nonlinear response arises due to non-uniform surface conduction over the curved particles. This nonlinear behavior introduces dependencies on fluid and particle properties not considered in the classical theory, offering potential advantages for microfluidic particle manipulation. While this phenomenon has been extensively studied theoretically and numerically in Newtonian fluids, experimental investigations have been relatively limited.

Fluid rheology can significantly alter particle dynamics under applied electric fields. Rheological properties like shear-thinning and elasticity which are not …

On The Structure, Energy, And Segregation Behavior Of Grain Boundaries In Metallic Systems, Yasir Mahmood

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Nearly all structural metallic systems are multi-component polycrystalline aggregates; their microstructures are composed of crystalline grains that are internally joined at grain boundaries (GBs). This thesis focuses on GB structure, energy, and chemistry, as these greatly influence many material properties and processes, including boundary dynamics during processing treatments or under operating conditions.

Using atomistic simulations, we examine the impact of metastable GB structures on solute segregation. A wide range of GB geometries and metastable structures are used in our study. The Al-Mg alloy is used because it is of interest for light weighting. The atomistic simulation results are used to …

Computer Vision Algorithms For Assessment Of Surgical Suturing Skill Using Hand And Needle Motion, Jianxin Gao

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Surgical suturing skill assessment is a crucial part of surgical education. Vascular surgery educators have developed a simulation-based examination called Fundamentals of Vascular Surgery, which includes a clock-face model for assessing open surgical suturing skills. The clock-face model, however, requires the valuable time of expert surgeons to determine examinees' skills. Moreover, expert surgeons have different judgments for appropriate sutures, which leads to inconsistent grading. These limitations motivate us to use sensors to measure examinees' needle motions and hand motions during the clock-face suturing exercises, and then use the measurements for objective suturing skill assessment.

To assess suturing skills based on …

Contribution Of Collagen Type I To The Mechanical Properties Of Myocardial Tissues At The Micron Level, Adam Baker

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Collagen is a critical component of the organization and one of the key factors contributing to the mechanical stability of the myocardium. Where cardiomyocytes actuate to contract the heart and deliver blood to the lungs and the entire body, the local collagen network must be able to support the mechanical needs of the heart by enhancing rigidity, reducing the mechanical responsibility of cells, and increasing compliance to add loading capacity during diastole. At an organ-wide level, this has been measured and modeled in many ways. At the tissue level, the mechanical properties have been evaluated using techniques such as bi-axial …

Lab To Leadership: How Do Women College Stem Students’ Classroom Experiences Inform Their Leader Identity Development?, Meredith Mcdevitt

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This dissertation is an exploration of leader identity development and women in science, technology, engineering, and mathematics (STEM) college academic classrooms. While there continues to be research promoting diversity in STEM professions, women remain underrepresented in STEM disciplines, leadership positions, and for this specific study, the college academic classroom. This dissertation represents an opportunity for women in STEM college students to reflect on their experiences in STEM academic spaces and communities, while self-exploring factors that shape their leader identity development. The research utilized a basic qualitative research design to understand the participant’s authentic experiences within the academic environment. Conducting semi-structured …

Base Case Shear-Wave Velocity Profiles And Non-Linear Material Property Models Of Local Site Conditions In South Carolina For Seismic Site Response Analyses, Ali Sedaghat Shirehjini

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This dissertation presents the development of base case small-strain shear-wave velocity ( ) profiles and non-linear materials property models of local site conditions in South Carolina for seismic site response analyses. The need to address South Carolina's seismic hazards is partly motivated by the 1886 Charleston earthquake (moment magnitude, M_w= 6.7 to 7.5). Required inputs for seismic site response analysis include profile down to a specified reference outcrop condition and non-linear material properties for each layer in the profile. Although firm rock (i.e., ≥ 2,500 ft/s) or hard rock (i.e., ≥ 9,850 ft/s) is commonly assumed for the …

Exploring The Synthesis Of Biobased And Chemically Recyclable Polysulfone Using Imine Chemistry, Vitasta Jain

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Plastic waste poses a major problem because of the chemical stability of these materials, leading to their accumulation in the environment and the leaching of toxic chemicals during their slow decomposition. Additionally, the use of depleting petroleum reserves for synthesis has made for an unsustainable production and risks due to use of chemicals hazardous to the environment and the individuals exposed to it.

To address these concerns, researchers have explored biobased feedstock and incorporating chemical recycling capabilities for a closed loop, sustainable process. One promising feedstock is lignin with its abundant functional groups that can be modified and utilized to …

The Development Of A Novel Cartilage Analog Scaffold For Chondral Regeneration, Vishal Thomas

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Focal Chondral Defects (FCDs) are cartilage injuries that affect about 900,000 Americans every year. Left untreated, these may lead to osteoarthritis and eventually necessitate painful knee replacements. Current treatment options are limited in terms of durability, cost, and availability of grafts. Tissue engineering, using natural scaffolds, are a highly attractive alternative promising cost efficiency, abundance, and long-term benefits. However, their low mechanical strength and dense matrices are impediments that could lead to sub-optimal repair.

In this work, a natural biomaterial, the bovine nucleus pulposus (bNP), derived from intervertebral disc tissue, was identified as a candidate scaffold for cartilage regeneration. Mechanical …

Linear And Nonlinear Topology Optimization With Morphing Beam Networks, Andrew S. Montalbano

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Topology optimization (TO) is an engineering design discipline dedicated to optimizing material distribution within a given domain. In traditional gradient-based topology optimization, the solid domain is discretized into small volumetric elements. Using finite element analysis (FEA) of the structure, the gradient of the objective function with respect to the design variables (the pseudo densities) is computed, and these design variables are updated iteratively until convergence is achieved. Although gradient-based TO methods are well-established, sensitivity analyses of objective functions and constraints can be both mathematically complex and computationally intensive. The nonconvex nature of most TO problems often complicates efficient convergence. Furthermore, …

Hybrid Physics-Infused Machine Learning Framework For Fault Diagnostics And Prognostics In Cyber-Physical System Of Diesel Engine, Shubhendu Kumar Singh

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Fault diagnosis is required to ensure the safe operation of various equipment and enables real-time monitoring of associated components. As a result, the demand for new cognitive fault diagnosis algorithms is the need of the hour. Existing deep learning algorithms can detect, classify, and isolate faults. Still, most depend solely on data availability and do not incorporate the system's underlying physics into their prediction. Therefore, the results generated by these fault-detecting algorithms sometimes need to make more sense and deliver when tested in actual operating conditions.

Similar to diagnosis, the fault prognosis of diesel engines is paramount in numerous industries. …

An Emergency Response System To Assist The Movement Of Vehicles During Emergency Operations In Urban Transportation Networks, Jamal Nahofti Kohneh

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Emergency responders need to arrive at the emergency scene as soon as possible, but operating vehicles under emergency conditions can pose a risk to both the responders and other road users, potentially resulting in crashes or delays in emergency operations. In this research, an emergency response system is proposed to assist emergency and non-emergency response vehicles (ERVs and non-ERVs) during emergency operations in a connected vehicle environment. This system collects the information from connected ERVs and non-ERVs, utilizes this information as inputs in the proposed models, and sends instruction messages back to vehicles. The proposed models provide the fastest ERV …

Monitoring Vehicle Seat Occupancy Status And Tracking Human Passenger Activities Inside Vehicle Passenger Cabins, Rahul Prasanna Kumar

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An autonomous vehicle (AV) is a promising engineering innovation that can operate without a human driver. Nonetheless, to ensure passenger safety and comfort in the absence of human drivers, the vehicle must continuously monitor and predict how the cabin’s state will evolve in the immediate future. The two major factors influencing the cabin’s state are the occupancy statuses of vehicle seats and the activities of human passengers occupying them. Therefore, this dissertation presents a system employing a capacitance-sensing mat and a machine learning unit to monitor vehicle seat occupancy status and track passenger activities non-intrusively. While the mat integrates with …

Measuring Cannulation Behavior On A Sensorized Simulator: Development, Verification, And Testing Of System Components, Lydia Petersen

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End Stage Kidney Disease (ESKD) is a significant public health burden in the United States. Life-sustaining hemodialysis, required up to three times a week for ESKD patients, necessitates a functioning vascular access. For proper cannulation, cannulators have many factors to consider, including an AVF’s geometry, depth, diameter, and other details. Poor cannulation can lead to infiltration, where the needle punctures the vessel wall. Infiltration occurs in as many as 50% of cannulations, causing complications ranging from hematoma and swelling to delayed treatment or loss of vascular access. This highlights the need for objective, standardized training methods to improve cannulation skills …

Efficient And Secure Data Transmissions In Emerging Heterogeneous Wireless Networks, Sihan Yu

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The widespread deployment of wireless devices facilitates the Internet of everything, greatly enhancing communication efficiency and improving people’s daily experiences. The interconnectivity of wireless devices relies on wireless communication technologies. With the development of various emerging communication technologies, wireless networks have become increasingly vast and complex, giving rise to numerous new challenges such as efficiency and security concerns.

In wireless networks, different devices may utilize different communication protocols, resulting in heterogeneous wireless networks. Communication among heterogeneous devices is challenging, often leading to conflicts and low communication efficiency when utilizing limited communication resources (e.g., spectrum resources). Moreover, the coexistence of heterogeneous …

Crystalline Colloidal Arrays: Exploring Light-Matter Interactions, Haley W. Jones

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Understanding and manipulating quantum light-matter interactions, especially in the context of nanostructured environments, is highly critical for technological progress and inventive solutions in the fields of telecommunications, energy-efficient lighting, and cutting-edge quantum computing technologies. The fundamental interactions of photons with a surrounding environment directly impact the performance and efficiency of devices such as lasers, light-emitting diodes (LEDs), and quantum computing elements, which leverage the unique properties of confined structured environments. Since the late 1980s, the connection between a structured environment and the decay kinetics of an embedded fluorophore has been a highly debated and unresolved topic in the literature. More …

Efficacy Of Virtual Reality-Based Simulations In Training Aviation Maintenance Technicians On Maintenance Procedures, Gayatri Anoop

All Theses

The COVID-19 pandemic forced institutions of higher education (IHEs) to halt in-person classes and transition to online platforms. Given the intricate process of adapting hands-on experiments to the online environment, this transition seemed particularly challenging for Science, Technology, Engineering, Mathematics, and Medicine (STEMM) labs. The abrupt nature of this transition added to the difficulties, given that the IHEs were inadequately prepared for seamless continuity during the pandemic. In the first phase of this project, a literature review was conducted to understand the impact of COVID-19 pandemic on education. Specifically, the review explored the challenges that institutions of higher education faced, …

Dynamics Of Link Importance Across Flood Disaster Phases And Flood Impacts On Operation Of An Industry, Navin Bhatta

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Transportation damage and disruptions will become increasingly common as the frequency of floods increases due to climate change. Given the size and cost of the transportation network construction, communities' mitigation measures should be supported by evaluations that cover both normal and disaster management phases. This thesis examines the criticality of road segments in the normal, flood response, and recovery phases, considering the effects on emergency services, healthcare, industry, education, recreation, and transit and analyses that whether a flood disrupts the operational trips of a company in Anderson County, South Carolina. A 100-year event and a 500-year flood event provides context …

Modeling Of Multi-Period Disaster Logistics Planning In The State Of South Carolina, Emma Simon

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South Carolina is one of the most vulnerable states in the United States to the impact of hurricanes. Currently, when threatened with a natural disaster such as a hurricane, the state government makes many vital decisions based on knowledge and experience. In this study, the distribution of disaster relief commodities to meet immediate needs is analyzed through two models for the case of South Carolina to generate an optimal logistics strategy that considers the social vulnerability of affected populations. The first model is a multi-objective pre-disaster logistics model that uses a four-index formulation for the multiple trip vehicle routing problem. …

Release Of Small Molecules From Rubber: Effects Of Materials Properties, Mechanical Loading And Molecular Interactions, Yongcan Du

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Release of small molecules from polymeric materials has wide applications in the delivery systems of active molecules such as drug, fragrance, and semiochemical. Rubber materials are good candidates for the excipients of those systems due to properties such as good flexibility, permeability, and biocompatibility. Factors like material properties, mechanical loading, and molecular interactions may affect the release of small molecules in those systems. Therefore, understanding how those factors affect the release is key to the formulation, design, and evaluation of those systems.

To study the effects of materials properties, vulcanized natural rubber sheets with different crosslink densities, loaded with small …

Robust And Trustworthy Deep Learning: Attacks, Defenses And Designs, Bingyin Zhao

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Deep neural networks (DNNs) have achieved unprecedented success in many fields. However, robustness and trustworthiness have become emerging concerns since DNNs are vulnerable to various attacks and susceptible to data distributional shifts. Attacks such as data poisoning and out-of-distribution scenarios such as natural corruption significantly undermine the performance and robustness of DNNs in model training and inference and impose uncertainty and insecurity on the deployment in real-world applications. Thus, it is crucial to investigate threats and challenges against deep neural networks, develop corresponding countermeasures, and dig into design tactics to secure their safety and reliability. The works investigated in this …

A Comprehensive Materials Approach To Thermal Management In Fiber Lasers, Bailey Meehan

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Optical fiber-based amplifiers and lasers enable a great many useful devices and conveniences. Unfortunately, however, they can generate considerable heat during operation that drives the need for complex cooling solutions, thus reducing many of the size, weight, and power (SWAP) benefits for which fiber lasers are known. Additionally, at elevated temperatures, thermally-driven phenomena, such as Transverse Mode Instability (TMI), can be induced that limit the power-scaling of fiber lasers. The focus of this Dissertation is to explore novel approaches to thermal management in fiber lasers through judicious materials science and engineering to obviate the aforementioned limitations. Fibers studied in this …

The Development Of A Convenient And Consistent Methodology For Flight Proficiency To Certify Multi-Rotor Uas Pilots For State Departments Of Transportation, Colin Dees

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To fly an unmanned aircraft system (UAS), commonly referred to as a “drone,” the Federal Aviation Administration (FAA) requires pilots to pass a knowledge test. There is no requirement at the state or federal level for drone operators to demonstrate the ability to operate a UAS. The National Institute of Science and Technology (NIST) has created an exam for public and private entities to assess basic UAS flight proficiency. It is the only nationally recognized flight proficiency protocol. NIST does not provide a scoring recommendation and leaves it to the user to determine the minimum criteria to pass. There is …