Engineering Commons^™

Laser-Induced Acoustic Signal Generation, Resonance Characterization, And Optical Sensing In Metallic Plates, Xinghang Zhao

All Theses

This thesis investigates laser-induced acoustic signal generation, resonance characterization, and optical sensing in metallic plates as a foundational study for damage-sensitive inspection. Rather than presenting a complete defect-detection system, the work focuses on how measurable acoustic responses can be generated, amplified, and interpreted in a controlled laboratory setting. Experiments showed that pulsed-laser excitation can produce strong and repeatable acoustic responses in metallic structures. Repetition-rate sweeping identified narrow resonant responses, including a cantilever resonance at 57.862 kHz and a maximum circular-disk response at an FFT frequency of 48.8 kHz with a laser repetition rate of about 49.1 kHz. High-Q resonances exceeding …

Field Testing Of Retrofits To Improve The Structural Behavior Of South Carolina Flat-Slab Bridges, Jacob Bowers

All Theses

The South Carolina Department of Transportation manages approximately 2,300 “flat-slab” bridges statewide, with an average age of 58 years, according to the National Bridge Inventory (NBI 2024). Many of these structures were originally designed for H10 or H15 truck loadings, which are significantly below current design standards. As a result, numerous bridges have been load-posted, restricting freight movement, emergency response, and local connectivity. While full replacement provides a long-term solution, it is often cost-prohibitive and disruptive. Accordingly, the South Carolina Department of Transportation is seeking cost-effective retrofit strategies that improve performance and extend the service life of these bridges. Implementing …

Estimation Of The Mechanical Properties Of South Carolina Timber Piles Using Non-Destructive Evaluation Methods And Experimentally-Informed Models, Aashish Sapkota

All Theses

South Carolina has about 2,600 bridges that are supported by nearly 75,000 timber piles. They are increasingly vulnerable to biological decay, cracking and impact damages after decades of service. Current inspection methods used by the South Carolina Department of Transportation (SCDOT), such as hammer sounding and awl probing, are labor-intensive and expensive. This study investigated non-destructive evaluation (NDE) methods, including micro-resistance drilling and stress wave timing, as alternatives for assessing timber pile condition.

Ten timber piles were collected from two South Carolina bridges, and their above-grade portions were cut into 40 specimens approximately 13 to 15 inches long. Specimens were …

Neural-Network-Based Modeling Of Grid-Forming Inverters, Jacob D. Levesque

All Theses

Renewable energy production has grown significantly in recent years and continues to expand, resulting in an increasing number of inverter-based resources (IBRs) in the grid. As the number of IBRs in the grid continues to grow, grid-forming (GFM) inverters are becoming increasingly popular due to their ability to regulate voltage and frequency, providing increased grid stability and enabling islanding. As GFM inverters become more widely used in power systems, accurate and efficient models of their behavior are needed for system design purposes.

Emerging advances in neural networks have led to research on computationally efficient neural-network-based (NN-based) modeling approaches for inverters. …

Multimodal Aerial Image-Based Ground Object Detection And Classification Using Yolo, Erik Nielsen

All Theses

Object detection in unmanned aerial vehicles (UAVs) present a unique challenge due to small object sizes, varying viewpoints, and changing environmental conditions. These challenges are exacerbated when operating during daytime and nighttime scenarios where illumination differences can heavily impact detection performance. This work is motivated by military object detection applications where the ability to reliably identify small objects such as landmines or unexploded ordnance from aerial imagery presents a critical safety need and a significant technical challenge. In this paper, we investigate object detection using both visible (RGB) and infrared (IR) imagery to improve robustness and reliability across diverse operating …

The Impact Of Dipeptides On Product Quality In Chinese Hamster Ovary Cells, Louise C. Herman

All Theses

Biopharmaceuticals are medicines produced in cells which are used to treat diseases such as cancer. Monoclonal antibodies (mAbs) represent the majority of approved biotherapeutics. MAbs are mostly produce using Chinese hamster ovary (CHO) cells. CHO cells are favored for resiliency, scalability, and established safety, and are considered the “workhorse” organism for biopharmaceuticals.  Amino acids are a key component of cell culture media, however several amino acids have solubility limits, such as cysteine, cystine, and tyrosine.  At neutral pH, these amino acids are poorly soluble.  However, dipeptides, such as N,N'-di-L-Alanyl-L-Cystine (ACCA) have been reported to increase cysteine and cystine availability. Further, …

Fluorescence-Based Quantification Of Hepatic Ldl Uptake And Donor Hepatocyte Engraftment Using Atto 700–Labeled Ldl, Victor Agustin Cortes Flores

All Theses

Familial hypercholesterolemia (FH) is an inherited disorder characterized by elevated low-density lipoprotein cholesterol (LDL-C) that increases the risk of premature atherosclerotic cardiovascular disease. In severe FH, including low-density lipoprotein receptor (LDLR), hepatic LDL clearance is profoundly impaired and many lipid lowering treatment strategies have limited effectiveness. Current advances in ex vivo CRISPR–Cas9 hepatocyte gene editing in vivo and ex vivo approaches for treatment of FH are under development.

However, a central barrier to translation is the ability to quantitatively measure the percentage of healthy gen edited hepatocytes in the liver while simultaneously assessing functional hepatic LDL handling. This thesis establishes …

Increasing The Number Of Injections Per Cycle In A Gasoline Compression Ignition Strategy: An Experimental Study, Joshua Murray

All Theses

Gasoline Compression Ignition (GCI) is an advanced compression ignition strategy which utilizes the high octane number of gasoline to improve diesel soot and NOx emissions by enabling partially premixed injections of fuel. GCI work in the literature typically uses single, double, or triple injection strategies, with higher numbers of injections noted for their ability to achieve low MPRRs, improved soot and NOx emissions, and higher efficiency. Thus, this study extends the literature by evaluating quadruple and quintuple injection strategies for continued improvement in engine efficiency and emissions.

The experiments in this work are conducted on a heavy-duty Detroit Diesel DD13 …

Exercise-Induced Muscle Damage As A Model For Exploring The Effects Of Pain On Gait, Sydney Savage

All Theses

Persistent gait asymmetry following anterior cruciate ligament reconstruction (ACLR) is a recognized contributor to post-traumatic knee osteoarthritis, yet the independent role of pain in driving altered movement patterns remains poorly understood due to confounding factors inherent to clinical populations. This study used exercise-induced muscle damage (EIMD) as a controlled experimental model to isolate the effects of musculoskeletal pain on gait, independent of kinesiophobia, structural damage, and proprioceptive disruption. Eighteen healthy adults underwent unilateral eccentric calf-raise protocols to induce delayed onset muscle soreness (DOMS), with gait assessed at baseline, 48 hours, and 168 hours post-exercise using bilateral inertial measurement units. Outcomes …

Design And Development Of A Perfusable Hydrogel Platform With Bioprinted Human-Endothelialized Microvascular Channels, Calvin A. Chernyatinskiy

All Theses

We developed an integrated bioprinting and perfusion platform to generate vascularized hydrogel constructs that support perfusable microchannel networks. Multiple hydrogel formulations, sacrificial ink systems, device geometries, and perfusion conditions were systematically evaluated to optimize print fidelity, mechanical stability, and cellular compatibility. Internally gelling alginate–calcium carbonate hydrogels were identified as a robust matrix, providing tunable gelation kinetics and structural stability during embedded printing. In parallel, Pluronic F-127 fugitive ink enabled reliable fabrication of continuous hollow channels due to its shear-thinning behavior and efficient post-print removal.

The finalized platform integrates stereolithographically fabricated perfusion chambers with extrusion-based bioprinting to produce three-dimensional, perfusable vascular …

Development Of Low-Cost Triaxial Force Sensor For Measurement Of Human-Exoskeleton Interaction Forces, Hamdan Khan Sarvathullah

All Theses

Contemporary research suggests that shear force is a major contributor to discomfort and pressure injury. However, the variation of shear forces during human-exoskeleton interaction dynamics is a highly unexplored field. The high cost of commercial triaxial force sensors may be a major factor in the notable lack of research in this field. Therefore, in this paper, we present a low-cost, 3D-printed triaxial force sensor designed specifically to measure the triaxial interaction forces between an exoskeleton and its user. The triaxial force sensor uses Carbon-Black/Silicone Rubber (CB/SR) strings to measure shear forces, whereas the normal force is measured with a Force …

Analysis Of Potential Alkali Reactivity Of Aggregates In Arkansas, Brigita Dowling

Civil Engineering Undergraduate Honors Theses

Alkali Silica Reaction (ASR) is a deleterious chemical reaction in concrete that leads to the deterioration of concrete structures. This reaction occurs between minerals present in aggregates and alkalis in the cement, and produces a gel-like substance called alkali silicate gel. Gradually, these gels absorb water from the environment and expand, leading to internal stresses in the concrete. This damage results in expansion, cracking, and deformation, reducing the strength and durability of the concrete significantly. While this damage appears minor initially, eventually they can lead to the need for costly repairs or replacement of the concrete. ASR has been observed …

Chloronitramide Anion Yields During Monochloramine Formation: Impact Of Reagent Addition Order, Ph, And Mixing, Barrett E. Johnson, Julian L. Fairey, Jason A. Thornhill

Civil Engineering Undergraduate Honors Theses

Chloronitramide anion was recently identified as a decomposition product of inorganic chloramines. Tap‑water concentrations > 300 μg/L reported in a recent study prompted this investigation of chloronitramide anion during monochloramine formation under conditions relevant to drinking water treatment plants. As monochloramine is formed by mixing free chlorine with free ammonia, the impacts of pH, reagent mixing intensity, and reagent addition order were assessed on monochloramine and chloronitramide anion yields. Jar tests were conducted in distilled deionized water at target pH levels of 7 and 9 under rapid, slow, and no‑mixing conditions, with alternating reagent order addition and a target monochloramine dose …

Uav Blast Load Characterization For Structural Design, Jalee Grace Spain

Civil Engineering Undergraduate Honors Theses

As the use of drones, or UAVs, increases, so does the risk of collision with infrastructure. When drones collide with a building, an impact or blast load is applied. Using current literature and structural analysis, a load case can be defined for a blast load induced by a drone.

Spatial And Temporal Patterns Of Bike-Share Use In A Small City: A Case Study Of Fort Smith, Arkansas, Brianna L. Buenger

Civil Engineering Undergraduate Honors Theses

Many small and mid-sized cities in the United States face ongoing transportation challenges due to limited public transit options. This can prevent residents from being able to reach essential destinations. While bikeshare systems have been widely studied in large metropolitan areas, there is limited understanding of how usage patterns vary across space, time, and trip characteristics in small-city contexts. This study addresses this gap by examining spatial and temporal patterns of bikeshare use in a small U.S. city through a case study of the Fort Smith, Arkansas, SMILIES bikeshare program. Using approximately 10,000 trips over three years, the analysis examines …

Extremum Seeking Compensation And Quantification Of Position Sensor Offset Error In Speed-Controlled Permanent Magnet Synchronous Motors, Tessa Biondo

Masters Theses

Position sensor offset errors present a persistent challenge in speed-controlled permanent magnet synchronous motor drives operating under field-oriented control. Even small, constant offsets in the measured rotor position can reduce torque effectiveness, requiring increased current and voltage demand to maintain the commanded speed and resulting in degraded speed regulation performance across a range of operating conditions. These effects are particularly problematic in speed-controlled systems, where speed loop dynamics cause increased electrical effort and limit overall performance. Many existing detection and compensation approaches are either dependent on the system model, require offline calibration, or are primarily designed for torque-controlled operation. This …

Dor-E: Final Design Report, Arav Singh, August Hogen-Esch, Bruce Le, Patrick Mcgee, Spencer Major

Mechanical Engineering

I. PROBLEM STATEMENT

The Chumash Heritage National Marine Sanctuary contains a diverse array of benthic habitats that remain largely undocumented due to the financial and logistical barriers of deep-sea exploration. Traditional high-end autonomous underwater vehicles and remotely operated vehicles capable of reaching 1000-meter depths require significant surface support infrastructure and hundreds of thousands of dollars in funding. Furthermore, navigating protected ecological zones demands strict adherence to "Leave No Trace" principles. Conventional benthic landers and submersibles routinely leave metallic debris behind; many submersibles use galvanic timed releases that corrode in seawater over a set period of time or heat-activated bolts to …

Ihelp Foundation 2025 Uganda Medical Mission, Kade Spencer Robison

Undergraduate Honors Capstone Projects

Uganda faces significant barriers to health care access, particularly in rural communities, due to physician shortages and limited resources. As a result, care is concentrated in urban areas, leaving rural populations disproportionately affected by both communicable and noncommunicable diseases.

This Honors Capstone project focused on preparing for and supporting the iHelp Foundation’s 2025 Uganda Medical Mission. The iHelp Foundation works to reduce barriers to care in Uganda by partnering with local hospitals to provide short-term rural clinics and specialized surgical care for advanced otolaryngological conditions.

In this project, I contributed to mission preparation by training volunteers and coordinating physician licensing. …

Enhancing Reliable Performance Of Microgrids With Autonomous Control Of Distributed Energy Resources, Sahand Liasi

All Dissertations

This dissertation presents a comprehensive investigation into enhancing the reliability, efficiency, and autonomous operation of modern power networks through advanced microgrid integration and control strategies. The research addresses critical challenges across three interconnected domains: microgrid control, thermodynamic modeling of heat recovery system (HRS), and optimal distribution network reliability.

In the realm of microgrid control, this work introduces novel methodologies for grid forming inverter-based resources (IBRs). A significant contribution is the development and validation of an "Auto Frequency Change" controller, which drastically reduces microgrid synchronization time with the main grid from several minutes to approximately four seconds, with theoretical potential for …

Development And Validation Of The Ampere Scale: Measuring Adaptive And Maladaptive Perfectionism In Engineering Students, Haleh B. Brotherton

All Dissertations

Perfectionism refers to the inclination to set very high expectations for oneself, which can at times encourage personal development and at other times lead to stress and a sense of pressure. Perfectionism is widely observed among engineering students; however, instruments that distinguish adaptive striving from concern-driven tendencies in the engineering context remain limited. My study is based on the development and validation of the AMPERE (Adaptive and Maladaptive Perfectionism in Engineering) scale through a three-phase process: (I) expert review with two domain experts to establish content validity; (II) cognitive interviews with seven undergraduates to refine wording and interpretability; and (III) …

Generative Ai Of Breast Cancer Progression In Gene Expression Space, Xusheng Ai

All Dissertations

Breast cancer is one of the most common and deadly cancers in the world. Although doctors can use gene activity data to better understand different types of breast cancer, it is still difficult to identify the most important genes and to track how the disease changes over time. This is partly because gene data are very large and complex.

This dissertation develops a computer-based framework to study breast cancer using gene expression data. The work focuses on three goals: creating realistic synthetic gene data, identifying important genes linked to cancer, and modeling how breast cancer changes from normal tissue to …

Investigation Of Low-Pressure Mercury Lamp System Configurations And Xenon Excimer Lamp System Development As Vacuum Ultraviolet Sources For Optimal Photolytic Degradation Of Poly-/Perfluoroalkyl Substances, Eman Zuhair Alhamdan

All Dissertations

PFAS are persistent synthetic chemicals, with unique properties that enable them to easily enter and accumulate in water sources. Their public health impacts have raised concern and highlighted the need for effective treatment. Numerous techniques for PFAS removal from water have been studied, few have proven the ability of breaking down PFAS rather than separating and concentrating it. Many of these methods are chain-length dependent, showing slower degradation rate of short-chain PFAS and requiring substantial amounts of energy, and chemical agents that may produce byproducts.

Among available PFAS destruction methods, direct photolysis by high-energy UV with wavelength below 200 nm …

Safe Control Design For Quadruped Locomotion In Unstructured Environments Using Linear Transfer Operators, Sriram Sundar Krishnamoorthy Shankara Narayanan

All Dissertations

Deploying quadruped robots in unstructured, obstacle-rich environments requires control and planning methods that remain safe and reliable despite complex terrain geometry, limited sensing, and inevitable modeling errors. This thesis develops operator-theoretic tools for safe control design of robotic systems using linear transfer operators, with a focus on quadruped locomotion in unstructured environments. The central goal is to develop a unified operator-theoretic framework for safe control design based on the Perron–Frobenius (P–F) and Koopman operators. In particular, the thesis leverages \emph{density functions} to develop safe navigation frameworks in the dual space of densities. In the operator-theoretic perspective, the P–F operator governs …

Interplay Between Phase Instability And Deformation Mechanisms In Beta Titanium Alloys In Aggressive Environments, Benjamin Elbrecht

All Dissertations

Modern designs, such as commercial jet turbines, are reliant on the high temperature performance of their constituent materials. Improvements to the strength-at-temperature of materials are critical to the continued advancement of efficiency and payload capacity in these advanced applications. This dissertation presents studies that progress towards this goal through the construction of a new experimental setup for complex temperature and force profiles that also accurately captures deformation behavior through non-contact measurements. Using this setup, studies into two specialty titanium alloys were executed: discovering the microscopic mechanisms responsible for the macroscale behavior and testing in conditions closely replicating aircraft turbine operating …

Learning Global Context For Sparse Activity Recognition In Lengthy Recordings With Limited Dataset Size, Zeyu Tang

All Dissertations

This dissertation describes methods to analyze lengthy recordings of data in order to detect sparsely occurring activities. The narrative below describes the progression of research that led to the development of these methods and their generalization into a unified framework. My research started with designing models for dietary monitoring, including detecting meals from day-long recordings and detecting intake gestures from meal-length recordings. Both tasks share some common characteristics: (a) the target event takes only a small portion of data recordings, and (b) there is global context within full-length data recordings that can help a model make better decisions. After finishing …

Experimental And Computational Investigation Of The Effects Of Neck Musculature During Head Impacts In American Football, Anthony P. Marino

All Dissertations

Anthropometric test devices (ATDs) are human surrogate models used to represent the human body response in the context of compliance and safety testing. These devices are used in multiple industries, including automotive and aerospace, and have recently been incorporated into impact testing for the evaluation of helmet performance in American football. The Hybrid III 50^th percentile male ATD head and neck assembly is the most commonly used surrogate for these tests, although it was developed for automotive frontal crash scenarios that induce an inertial force on the body, leading to head and neck motion primarily in the sagittal plane. …

Decision Making For Large-Scale Problems Under Uncertainty And Conflict, Benjamin J. Hamlin

All Dissertations

Large-scale decision-making problems appear in many areas including long-range forecasting such as energy generation forecasting. Many such problems are subject to conflicting objectives and uncertain data, and can be modeled as linear optimization problems. We study novel theoretical results and algorithms for large-scale linear decision problems under conflict and uncertainty. First, we propose a parametric Benders decomposition algorithm for solving large-scale linear optimization problems with multiple objectives or deterministically uncertain objectives. Second, we extend the parametric Benders decomposition to a multi-stage setting, developing a parametric stochastic dual dynamic programming algorithm, which enables decision-making when conflicts and uncertainty have planning impacts …

Modernizing Plastics And Composites Manufacturing Using Hybrid Modeling Techniques, Luke Shannon

All Dissertations

Plastics and composites manufacturing encompasses a broad family of processes, including injection molding, resin transfer molding, compression molding, and extrusion, that together account for the vast majority of polymer and composite component production worldwide. These processes are inherently challenging due to the multi-physics nature of polymer processing, the vast possible combinations of resins, reinforcements, and additives, and the strong dependence of final part properties on process history. Among these processes, injection molding is one of the most widely deployed, producing high-volume components across automotive, medical, consumer electronics, and packaging industries. However, accurately monitoring and predicting process behavior in injection molding …

Optimal Allocation Of Flexible Servers In Healthcare Systems, Tong Zhang

All Dissertations

This dissertation investigates the optimization of worker allocation in healthcare systems, focusing on flexible staffing models and the strategic prioritization of healthcare tasks. This research explores the dynamics among pre-operative, operative, and post-operative care units under various cost and service-rate constraints, using a series of models that represent realistic healthcare scenarios within a comprehensive framework for improving patient flow and reducing waiting costs.

In Chapter 2, we model and analyze cross-trained nurse allocation policies within an inpatient surgical system. We model the surgical system as a tandem clearing queueing system and formulate Markov decision processes under different business rules governing …

Baseline Cervical Intervertebral Disc Biomechanics And Implications For Allograft Preservation, Nathan F. Buchweitz

All Dissertations

Neck pain has become an increasingly common orthopaedic healthcare issue. Evidence shows that degeneration of cervical intervertebral discs (the cartilage between the spinal vertebrae in the neck) may be associated. While disc degeneration in the lumbar spine has been extensively studied in relation to low back pain, it has received less attention in the cervical spine. Biomechanically, the cervical (neck) and lumbar (lower back) regions of the spine differ in function. Lumbar discs resist a greater burden of body weight, whereas cervical discs are adapted for mobility to aid flexible head orientation. Despite these key differences, disc injury and degeneration …