Engineering Commons^™

A Discrete-Time Adaptive Sliding Mode Controller For A Multicopter With A Suspended Payload, John Helzer

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This thesis presents a Discrete-time Adaptive Sliding Mode Controller (DASMC) for control of a multicopter with a suspended payload. DASMC is designed to stabilize the multicopter at a desired position while minimizing the load oscillations induced by a significant hanging payload. The proposed DASMC minimizes the need for system-specific parameters like tunable gains and improves robustness to both external disturbances and model uncertainties compared with existing controllers. The controller is designed for direct digital implementation on a variety of multicopter platforms with considerations like discrete-time design, adaptive gain shrinking, and saturation handling. When deployed on a real multicopter in an …

Characterization Of The Effects Of Waste Mullite Powder On Seawater Sea Sand Cementitious Materials, Xiao Sun, Zehui Zhou, Wenjie He, Yudong Bi, Yao Wang, Hengrui Liu, Rui Zhong, Hongyan Ma

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Maintaining the durability of coastal concrete structures while reducing construction costs remains a formidable challenge. Drawing inspiration from the volcanic concrete used by ancient Greeks and Romans, this study explores the feasibility of using waste mullite powder (WMP) with a high alumina content in seawater sea sand concrete to conserve natural resources and enhance durability. The experimental results demonstrate that the incorporation of seawater and WMP exerts detrimental impacts on the flow characteristics and workability of cementitious composites. While the sulfate content in seawater and sea sand can bolster the early strength of sea sand seawater concrete, sulfate attack compromises …

Geopolymer Clsm With Off-Specification Fly Ash And Bottom Ash: A Sustainable Approach To Hazardous Waste Utilization, Alexis K. Vandomelen, Ahmed A. Gheni, Eslam Gomaa, Mohamed A. Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Conventional controlled low-strength material (CLSM) is a self-consolidating cementitious material with high flowability and low strength, traditionally composed of cement, sand, and water. This study explores the sustainable utilization of off-specification fly ash (OSFA) and bottom ash (BA), classified as industrial by-products with potential environmental hazards, to develop eco-friendly geopolymer CLSM as an alternative to conventional CLSM. Sodium hydroxide (NaOH) was used as an alkali activator to stabilize and solidify both two-part (liquid NaOH) and one-part (solid NaOH pellets) geopolymer CLSM mixtures. These mixtures were evaluated based on flowability (ASTM D6103-17) and compressive strength (< 300 psi per ACI Committee 229 guidelines for excavatability). A cost analysis was also conducted. The results demonstrated that incorporating OSFA as a cement replacement increased water demand by 15% to meet flowability requirements, while BA substitution for sand led to segregation challenges requiring mixture adjustments. For two-part mixtures, higher carbon content in OSFA necessitated an increased water-to-fly ash ratio. All self-consolidating mixtures exhibited 1-day compressive strengths ranging from 5 psi (0.03 MPa) to 87 psi (0.6 MPa). One-part mixtures showed a 1% to 34% reduction in 7-day compressive strength compared to two-part mixtures, improving excavatability. Increasing the BA-to-OSFA ratio from 1:1 to 3:1 reduced water demand due to lower surface area but increased the NaOH/OSFA ratio. This study highlights the potential of geopolymer CLSM to reduce costs by up to 94% at current NaOH prices (USD 6 per cubic yard) while repurposing hazardous industrial by-products, offering a cost-efficient, sustainable, and environmentally responsible solution for CLSM production.

Ftir Characterization Of Asphalt Sara Fractions In Response To Rubber Modification, Mohyeldin Ragab, Eslam Deef-Allah, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Asphalt–rubber binders (A-RBs) have a long and deep history of use; however, little is known regarding the interrelated chemical behaviors and miscibility of rubber with the asphalt fractions [saturates, aromatics, resins, and asphaltenes (SARA)]. This study comprehensively attempted to address this knowledge deficiency by employing Fourier transform infrared spectroscopy (FTIR) to investigate the chemical evolution of A-RBs. A-RB interacted at 190 °C and 3000 min⁻¹ for 8 h was deemed to have the optimal rheological performance. FTIR of the liquid fractions of A-RB 190–3000 showed a prominent chemical shift in the SARA fractions, with new peaks that showed rubber …

Stabilizing Embankments Using Geosynthetic Reinforcement, Daryl Greer, Charlie Sun

Kentucky Transportation Center Research Report

Reinforced soil slopes (RSSs) can be a feasible solution for embankments where there exist right of way re-strictions, environmental issues, rolling or mountainous topography, unfavorable geology, and other limiting fac-tors. They can be an alternative to retaining walls or importing select fills to construct steeper, stable embankment slopes where flatter embankment slopes may result in unwanted impacts, costs, and maintenance issues. Thisreport discusses the advantages and limitations of using geosynthetic reinforcement to construct RSSs. Researchers investigated current design, specification, and construction practices to determine which practices can be adopted by the Kentucky Transportation Cabinet (KYTC). Specifications were developed for using …

Graduate School Blog - July 2025 Volume 1, Cynthia Haynes

UofM Grad School Blog

The July 2025 UofM Graduate School Blog – Volume 1 continues the Cost of Graduate School Guide with a deep dive into hidden and variable expenses such as residency-based tuition differences, program-specific fees, and differential tuition. The blog provides practical tips for prospective students on how to ask the right financial questions when comparing programs. It also features a student spotlight on Billy Brooks, a dual MHA/MBA candidate motivated to transform healthcare access and equity. Upcoming events include a Virtual Fall 2025 Open House with Financial Aid and USBS, a Dissertation Writers Retreat, and both in-person and virtual Graduate Student …

Characterization Of Lactobacilli-Containing Catheter Segments Developed By Using Selective Laser Sintered Mold., Caden Maners

Master of Engineering Theses

Catheter-associated urinary tract infections (CAUTIs) are a major healthcare burden with current prevention strategies offering limited success. This study presents a novel, self-coating biomaterial approach using a silicone-based bioink embedded with thermally sensitive probiotic strains (L. crispatus, L. rhamnosus, and L. reuteri). Catheter segments were fabricated via bio-injection molding using 3D-printed CAD molds. These Lactobacilli, selected for their probiotic and antimicrobial potential, serve as a non- antibiotic strategy to reduce infection risk. These segments were evaluated for mechanical strength (Shore A hardness), thermal stability (TGA/DSC), porosity and bacterial presence (SEM), biofilm formation (crystal-violet assay), as well as mass retention in …

Modeling Framework To Quantify And Gauge Project Cost Risks Due To Construction Material Price Volatilities Using Predictive Probabilistic Deep-Learning Algorithms And Stochastic Risk Modeling, Yasser Jezzini, Rayan H. Assaad, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Material price fluctuations pose significant challenges for executing construction projects and adhering to budgetary estimates. Existing research studies focused on forecasting construction material prices rather than quantifying and gauging overall project cost risks related to price volatilities, and they relied on traditional time-series forecasting methods that are incapable of offering full probabilistic distributions of price fluctuations and of providing a comprehensive assessment of risk uncertainties associated with material price fluctuations. This paper addresses these gaps by developing an integrated framework to quantify and gauge project risks due to construction material price volatilities. The framework's validity and practicality were demonstrated using …

Investigating The Thixotropy Of Fresh Struvite Cement-Based Composite: Insights On Mechanisms Of The Pastes’ Thixotropic Behavior, Ugochukwu Ewuzie, Abdulkareem O. Yusuf, Damilola Daramola, Monday Uchenna Okoronkwo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Struvite (ST) recovered during wastewater treatment has been sparsely applied in cement-based composites. This study systematically evaluated the thixotropic behavior of cement-struvite (CST) pastes, a mix of 5–20 % ST by mass of cement, and proposed the interaction mechanisms leading to the pastes' thixotropy. The hysteresis loop area was used to establish the pastes' thixotropy and investigate its relationship with increased ST content, temperature, and yield stress. In the thixotropic behavior model used, the equilibrium shear stress was employed to examine the CST pastes' irreversible change; the characteristic time of deflocculation was used to study the flocs destruction process; and …

Gallium-Containing Bioactive Glasses: Their Influence On Ion Release And The Bioactivity Of Resulting Glass Polyalkenoate Cements, Lana Margaret Placek, Danielle Lee Perry, Mark Robert Towler, Anthony William Wren

Chemical and Biochemical Engineering Faculty Research & Creative Works

A series of glasses (0.48SiO2 − [0.40-x]ZnO − 0.12CaO-xGa2O3, x = 0, 0.8, 0.16) was developed to formulate a series of Ga-containing glass polyalkenoate cements (GPCs). The solubility of GPCs was tested using DI water, and it was found that the sample containing the highest mol% of Ga, LGa-2, had the most Ga ion release. The GPCs were incubated in SBF, and SEM/EDS analysis revealed that the at% of P increased, while the at% of Si decreased, highlighting the CaP precipitation on the GPC surface. The at% of Ga also decreased, reinforcing the Ga release from the GPC. Cellular testing …

Nasa Design And Analysis Of Pegda Hydrogels For Microgreen Cultivation In Space, Kelly Wu, Gabriel Antigua, Artur Abramyan

Publications and Research

With the growth of the space economy worldwide, sustainable and soil-less food systems for long-duration space missions become increasingly important. In this study, Polyethylene Glycol Diacrylate (PEGDA) hydrogels were experimented with as a biocompatible medium in arugula microgreen growth without utilizing soil. Among the most considerable challenges was the fact that the plants' root growth exceeded the hydrogel capacity, which caused seedling dislodgment and starvation. To combat this, computer-aided design (CAD) was utilized to 3D print different mold designs to try and control root development further. The most promising of these designs were coil and tree-branch molds, promoting lateral or …

Research On Technology Opportunity Identification By Integrating Technology Attribute Analysis And Competitive Environment Scanning —— A Case Study Of Industrial Robots, Daobin Gao

Journal of Scientific Information Research

[Purpose/significance] Placing technology opportunity identification in the perspective of technology attribute analysis and competitive environment scanning provides intelligence support for enterprises to select technology opportunities and formulate technology competitive strategies in complex and changing market competition environments.

[Method/process] Using patents as the data source, first, the BERTopic model is used to explore potential technical topics, Secondly, starting from the technical attributes, and from both global and local perspectives, we propose indicators of technical importance and technical attention, and use their cross screening to select candidate sets of technical opportunities, Finally, a market competition intensity index that takes into account market …

Analysis Of Vision Transformers And Domain Adaptation In Long-Range Facial Recognition, Zachary Michael Swanson

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Atmospheric turbulence presents a significant barrier to long-range facial recognition, introducing severe geometric distortions and blur that degrade image quality. This thesis investigates deep learning approaches for mitigating these effects, with a focus on transformer based architectures and domain adaptation strategies.

An in-depth benchmarking study was performed using convolutional neural networks (CNNs) and vision transformers (ViTs) on the Husker BRIAR Research Collection from up to 500m (HBRC-500) face dataset. The results demonstrated that vision transformers, particularly hierarchical vision transformers like the shifted-window (Swin) transformer, outperform CNN-based models at long distances due to their ability to model global spatial relationships and …

An Exponential Cone Integer Programming And Piece-Wise Linear Approximation Approach For 0-1 Fractional Programming, Hoang Giang Pham, Thuy Anh Ta, Tien Mai

Research Collection School Of Computing and Information Systems

We study a class of binary fractional programs commonly encountered in important application domains such as assortment optimization and facility location. These problems are known to be NP-hard to approximate within any constant factor, and existing solution approaches typically rely on mixed-integer linear programming or second-order cone programming reformulations. These methods often utilize linearization techniques (e.g., big-M or McCormick inequalities), which can result in weak continuous relaxations. In this work, we propose a novel approach based on an exponential cone reformulation combined with piecewise linear approximation. This allows the problem to be solved efficiently using standard cutting-plane or branch-and-cut procedures. …

Towards Efficient Privacy-Preserving Deep Learning: He-Friendly Structures, Flexible Pruning, He-Efficient Architectures, And Secure Transformer Token Drop, Yifei Cai

Electrical & Computer Engineering Theses & Dissertations

Deep learning (DL) has become a powerful tool for solving complex problems, but developing DL models typically requires vast datasets, high computational resources, and expert knowledge—barriers that limit accessibility. Machine Learning as a Service (MLaaS) addresses this challenge by allowing resource-rich providers to deliver pre-trained DL models as services. However, privacy concerns arise: clients hesitate to share sensitive data, while providers protect their proprietary models. To address this, privacy-preserving MLaaS integrates cryptographic techniques into DL computations, as seen in frameworks like Cryptonets, SecureML, GAZELLE, CrypTFlow2, Cheetah, and BOLT. Among them, Homomorphic Encryption (HE) enables computation on encrypted data but remains …

Advanced Study Of Nickel-Titanium Alloy: Effects Of Point Defects On Mechanical And Thermodynamic Properties, Diego Armando Juarez Rosales

Open Access Theses & Dissertations

High-throughput first-principles calculations of point defects are emerging as a powerful tool to accelerate materials discovery in applications [1]. Substitutional, antisite, and vacancy defects can play an important role in the mechanical and thermal properties of intermetallic alloys [2]. In this present work I compute the thermal and mechanical properties of shape-memory alloy nickel-titaniun (NiTi) in the B19â?? martensitic and B2 austenitic phases from molecular dynamics (MD), using a second nearest neighbor (2NN) modified embedded atom method (MEAM) [3] classical potential in the temperature range from 200K to 600K and composition range from 45 atomic percent to 55 atomic percent …

Database Development For Reliable Small Object Detection In Maritime Environments, Jacob Matthew Whisenant

Theses and Dissertations

Achieving high reliability in small object detection is critical for advancing maritime and littoral intelligent navigation operations. Computer vision provides an undetectable form of perception that can be easily integrated into existing camera systems, offering a low-profile yet powerful solution for navigation and situational awareness in water-based environments. While deep learning techniques have significantly advanced the field of computer vision, the detection of small objects remains a persistent challenge. Limited pixel representation, the scarcity of large-scale small object datasets, and the reduced detail and indistinct features of small objects complicate detection efforts, especially in complex environments. These factors collectively hinder …

Integrating Ensemble Hydrologic Forecasts With Policy Optimization Models For Forecast-Informed Reservoir Operations (Firo), Alessandra Estefania Perez Salas

Theses and Dissertations

Effective reservoir management in hydrologically variable regions such as California’s Central Valley faces increasing pressure to balance flood control, water supply reliability, hydropower generation, and ecosystem health. Traditional rule-based operations, while operationally simple, often lack the adaptability required to respond to real-time hydrologic conditions and forecast uncertainty. This study presents an integration of a policy tree optimization model with ensemble streamflow forecasts to enhance Forecast-Informed Reservoir Operations (FIRO) at Folsom Reservoir. Building on historical data for inflow, storage, and release, an interpretable, threshold-based decision framework was developed and coupled with 14-day ensemble inflow forecasts from the California-Nevada River Forecast Center’s …

Hydrogen Permeation And Mechanical Behavior Of Hydrogen-Charged Cr-Coated And Oxidized Zr-Alloy Fuel Cladding, Daniel Cole Viands

Theses and Dissertations

Following the Fukushima nuclear accident in 2011, accident tolerant fuel (ATF) became a major research interest to enhance the safety of light water reactors. Because the current fleet of light water reactors and their associated fuel cycle infrastructure are well-established, developing ATF that does not significantly alter the current fuel form or change its supporting infrastructure is ideal. Cr-coated Zircaloy fuel cladding is therefore an excellent short-term solution to enhance accident tolerance. Thin layers of Cr-coating offer notable resistance to corrosion, high-temperature oxidation, physical wear, and hydrogen permeation. Cold spray (CS) and physical vapor deposition (PVD) are two well-established Cr-coating …

Saw Biosensor For The Detection Of Cyanobacteria And Cyanotoxin, Tally Bovender

Theses and Dissertations

The growing prevalence of cyanobacterial blooms and associated cyanotoxins, such as microcystin-LR (MC-LR), presents a significant threat to water quality and public health. Conventional detection methods, including ELISA and PCR, are often time-consuming, expensive, and require trained personnel, limiting their application in field settings. Hence, a miniaturized, quick testing sensor is proposed to circumvent the current sensing challenges for real time, in-situ diagnostics of MC-LR. The proposed high-frequency ultrasonic sensor employs surface acoustic waves (SAW). The sensor was designed using a multi-physics simulation tool to understand wave propagation in the piezoelectric substrate (lithium tantalate) and optimize the design of the …

Optical And Thermal Characterization Of Vertically Conducting Β-Ga₂O₃ Diodes Grown On 4h-Sic Substrates For Short-Wavelength (<254 Nm) Detection, Muhammad Hassan Tahir

Theses and Dissertations

The advancement of compact, thermally stable, and efficient devices for deepultraviolet (DUV) detection below 254 nm is critical for solar-blind sensing, radiation monitoring, and high-power electronics. This thesis presents the growth, fabrication, and detailed optical and thermal characterization of vertically conducting β-gallium oxide (βGa₂O₃) Schottky barrier diodes (SBDs) grown on n-type 4H-Silicon Carbide (4H-SiC) substrates using metal-organic chemical vapor deposition (MOCVD).

β-Ga₂O₃ is an ultra-wide bandgap (UWBG) semiconductor (~4.8 eV) with intrinsic DUV transparency and high breakdown electric field, making it an ideal candidate for short-wavelength photodetection. However, its low thermal conductivity limits its vertical device performance. To overcome this, …

Design Of Supercritical Reactors To Understand Supercritical Water Oxidation Process And Hydrothermal Flames, Victor Dubceac

Theses and Dissertations

Supercritical water oxidation (SCWO) has been a topic of immense interest as an effective technique/tool for hazardous aqueous waste disposal. SCWO can be achieved by introducing an oxidizer (e.g., H2O2), or a hydrothermal flame as an internal source of both heat and oxidizer species in an aqueous environment at conditions above the critical point of water (P > 218 atm and T > 647 K). SCWO poses important environmental advantages for the treatment of harmful organic materials contained in waste streams. An SCWO reactor has the potential to be compact in design and therefore can be an ideal alternative to existing technology …

Effect Of Growth Conditions On The Performance Of Vertically Conducting Beta-Ga2o3 Diodes On 4h-Sic Substrate By Mocvd, Nifat Jahan Nipa

Theses and Dissertations

This thesis highlights the critical influence of doping strategies, specifically co-delta doping with silicon (Si) and indium (In), on improving the structural quality and device performance of β-Ga₂O₃-based Schottky barrier diodes (SBDs). To achieve better thermal management, β-Ga₂O₃ thin film was grown on bulk 4H-SiC substrates using the Metal-Organic Chemical Vapor Deposition (MOCVD) technique, renowned for its precise control over composition, thickness and doping profile. The ultra-wide bandgap (UWBG), high critical breakdown field and low turn-on resistance of β-Ga₂O₃ make it a strong candidate for next-generation power electronics and short-wavelength detection in extreme environments. However, the presence of structural defects …

Reduced Order Model-Based Framework For Microsecond Model Updating Of Two-Dimensional Structural Systems Using The Local Eigenvalue Modification Procedure, Emmanuel Abiodun Ogunniyi

Theses and Dissertations

Real-time model updating is crucial for active structures and electronic assemblies subjected to high-rate dynamic events. High-rate dynamic events refer to events that occur at high speeds and with rapid changes in the forces and energy involved. These events can include explosions, impacts, and crashes. These systems are characterized by a high dynamic response with a high rate (< 100 ms), high amplitude (> 100 gn), highly nonlinear, meaning that the response is not proportional to the applied force, and involve complex interactions between multiple objects or materials. A system exposed to high-rate dynamic environments is frequently prone to rapid plastic deformation, involving violent and …

Generalized Dynamic Pole Placement Control For Voltage Source Converters With Inductive-Capacitive Output Filters, Byunghee Moon

Theses and Dissertations

Voltage Source Converters (VSCs) with inductive-capacitive (LC) filters are prevalent in power electronics applications. There are many control techniques utilized for that category of power converter topology. However, as converter applications continue to increase their switching frequency, faster control methods are desirable to take advantage of the higher bandwidth that increased switching frequency allows for

Dynamic pole placement (DPP) controls are very promising methods for achieving high-speed control of VSCs with LC filters. However, the conventional DPP controls have very high sensitivity to disturbances and noise. In order to address this, two novel DPP current control methods are proposed and …

Characterizing The Relationships Between Cranial Geometry, Brain Morphometry, And Brain Mechanical Properties Using Mr Imaging And Elastography, Jessica Restivo

Theses and Dissertations

Traumatic brain injury (TBI) is a global health concern, with over 69 million cases annually. TBI risk depends on subject-specific neuroanatomical variation, yet research often only considers generic finite element (FE) models, based on the geometry and material composition of a 50th percentile male head. Although highly accurate, subject-specific models require expensive magnetic resonance (MR) imaging, elastography, and time-consuming computational resources. There is a need to create subject-specific TBI models that account for subject-specific variations, without neuroimaging. This study aims to create mathematical models to predict brain morphometry (dimensions, volume) [Objective 1] and mechanical properties (shear stiffness, damping ratio, octahedral …

Addressing Key Challenges In Mhz Power Converters, Aqarib Hussain

Theses and Dissertations

Power electronics are essential in applications such as aerospace, electric vehicles, and electric ships where compact, efficient, and high power-density converters are increasingly demanded. This push toward miniaturization has led to converter designs operating at switching frequencies in the megahertz (MHz) range. Higher-frequency operation enables significant reductions in passive component sizes—particularly transformers and inductors—thereby facilitating dense packaging. However, these benefits come with new challenges, including increased thermal stress, complex semiconductor behavior, higher-frequency magnetic design constraints, and elevated electromagnetic interference (EMI).

This research addresses several key challenges in MHz converter design. The first part involves the development of a 1-MHz, 1-kW …

Self-Regulated Thermal Management With Shape-Memory Alloy Torsional Tubes, Paula Sanjuan Espejo

Doctoral Dissertations and Master's Theses

The need for dynamic thermal management that adapts to varying system needs and requirements is a growing topic of interest in different engineering disciplines, most prominently aerospace and electronics. This demand for improved thermal management systems comes from the general increase of system efficiencies leading to an increase in component energy density. Shape-memory alloy actuators, which respond with a mechanical shape recovery to variations in temperature, can be used as self-regulated thermal management actuators that are able to respond to environmental thermal changes autonomously. In this dissertation, modeling and experimental analysis of a two-way shape-memory effect trained SMA torsional tube …

Investing Hysteresis In Floodplain Dynamics Of Lakes In The Middle St. Johns River Using Sentinel-1 Sar Imagery, Keenan Hubbard

Doctoral Dissertations and Master's Theses

Floodplain dynamics are often complex, with hysteresis potentially affecting the temporal relationship between flood stage and flood extent during subsequent inundation phases. This study leverages Sentinel-1 synthetic aperture radar (SAR) imagery to map flood extent in the Middle St. Johns River Lake floodplains and examine the presence of hysteresis during flood events. SAR scenes corresponding to river gauge readings were analyzed from the rising and falling limbs of a flood hydrograph. By comparing these flood maps, we assess differences in inundated areas at equivalent water levels during each stage of the flood event. The findings aim to enhance flood monitoring …

Experimental Analysis Of Satellite Operator Training Using Game-Based Virtual Reality Simulation, Lana Laskey

Doctoral Dissertations and Master's Theses

Satellite data plays a vital role in modern global infrastructure by enabling communications, navigation, and weather forecasting. As demand for satellite technology grows, so does the need for highly trained satellite ground operators. Traditional training regimens for satellite operators employ simulation using two-dimensional computer console displays paired with the varied ability of trainees to generate abstract mental imagery of the scenario. However, this development of mental imagery imposes a considerable learning curve and cognitive workload on the trainee, which may negatively impact the user experience and knowledge gained during the training scenario.

This experimental study investigated the effects of game-based …