Engineering Commons^™

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 …

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 …

Embeddable Multi-Material Wireless Micro-Sensors Utilizing Additive Manufacturing And Enhanced Microstructure, Nicholas Reed

Doctoral Dissertations and Master's Theses

The development of embeddable, multi-material wireless microsensors offers transformative potential for structural health monitoring (SHM) in aerospace applications. This work integrates additive manufacturing (AM) techniques with advanced microstructural design to produce flexible, high-resolution sensors that can be directly embedded into polymer substrates. By utilizing the vat photopolymerization process, customized embedded sensors are seamlessly integrated into polymer AM structures. These sensors are then continuously refined, targeting increases in performance, both internal and external. Microstructural enhancements are explored to modify the rheological properties of the fabricated embedded sensing channels and enhance the adhesive bonding between the embedded sensor and the AM structure. …

Mtu-Llm: Llm-Based Multi-Robot Task Allocation And Path Planning For Heterogeneous Robots In Search And Rescue Operations, Kaushik Kannan, Jungyun Bae

Michigan Tech Publications

Urban Search and Rescue operations after natural disasters involve locating and assisting victims in hazardous environments, which is challenging. Classical Multi-Robot Task Allocation (MRTA) and path planning approaches have been used to deploy heterogeneous robot teams in unsafe areas. However, existing methods often lack focus on workload balance and requirement fulfillment and struggle to generalize across different scenarios. To address these challenges, we propose Multi-robot Task allocation Utilizing LLMs (MTU-LLM), a framework designed to reduce the development time for task allocation and path planning approaches, enabling faster robot deployment. The framework uses an LLM-based “prompt engineering” approach that generates task …

Evaluation Of Waste Plastic Addition Via Dry Method On Asphalt Mixture Performance, Isabella Madeira Bueno

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Incorporating waste plastic (WP) into hot mix asphalt (HMA) offers a promising approach to enhance recycling rates and improve asphalt concrete (AC) performance, particularly in moisture damage resistance. However, results vary widely due to differences in WP types, sizes, and mixing methods. The lack of standardized procedures, especially for the dry process, has led to inconsistent integration and unclear roles of WP in AC mixtures. Studies suggest that introducing WP to pre-heated aggregates at temperatures exceeding its melting point can enhance mixture resistance to rutting, cracking, and moisture damage. In this context, this study was conducted in two phases to …

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 …

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 …

Satellite Radar Imagery Analysis For Ground Hazard Risk Monitoring In Railway Tracks And Slopes, Sumanth Varma Byrraju

Theses and Dissertations

Railway transportation is essential to national economies globally, and disruptions from geohazards can result in significant operational delays and considerable economic consequences. Satellite radar technologies, including Interferometric Synthetic Aperture Radar (InSAR), offer an effective means to monitor geohazard risks across extensive railway networks. This thesis employs Multi-Temporal InSAR (MTInSAR) techniques, including Persistent Scatterer InSAR (PSInSAR) and Small Baseline Subset (SBAS), to identify high-risk areas along railway rights of way (ROW) prior to geohazard occurrences. However, the efficiency of these MT-InSAR and, consequently, the caliber of the data generated may be restricted by elements like topographical profile, vegetation, and surface soil …

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 …

Strain And Redox Engineering For Enhanced Thermoelectric Performance In Transition Metal Oxide Thin Films, Mohammad Jamal El Loubani

Theses and Dissertations

The discovery of highly efficient and cost-effective thermoelectric (TE) materials is essential to envision high-performance TE power generators that enable the direct conversion of waste heat into electricity. Transition metal oxides (TMOs) are considered promising candidates for high-temperature TE applications due to their excellent thermal stability and low cost. However, their maximum power output (power factor, PF = σ•S2) is constrained by the intrinsic trade-off between thermopower (S) and electrical conductivity (σ), both of which are inversely related to carrier concentration. This trade-off poses a significant barrier to improving the performance of TE devices. Among various strategies to overcome this …

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 …

Elevating Next Generation Wireless Devices Towards Contactless Sensing For Healthcare Applications, Aakriti Adhikari

Theses and Dissertations

There is an increasing interest in technologies that can understand and perceive at-home human activities to provide personalized healthcare monitoring, aimed at early detection of disease markers and assisting physicians in making clinical decisions. Existing approaches, such as wearables, require users to wear sensors that can be cumbersome and cause discomfort. Vision based solutions, such as optical cameras, IRs, LiDARs, etc., can be used to design contactless at-home monitoring systems. However, these systems are limited by poor lighting and occlusion, and they are privacy-invasive. Fortunately, high-frequency millimeter-wave wireless devices provide an effective alternative to the existing systems to enable fine-grained …

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 …

Cell-Free Protein Synthesis Reactor Formats: A Brief History And Analysis, Dallin M. Chipman, Anna C. Woolley, Davu N. Chau, William A. Lance, Joseph P. Talley, Tyler P. Green, Benjamin C. Robbins, Bradley Charles Bundy

Faculty Publications

Cell-free protein synthesis (CFPS) has transformed protein production capabilities by eliminating cellular constraints, enabling the rapid expression of difficult-to-produce proteins in an open, customizable environment. As CFPS applications expand from fundamental research to industrial production, therapeutic manufacturing, and point-of-care diagnostics, the diverse array of reactor formats has become increasingly important yet challenging to navigate. This review examines the evolution and characteristics of thirteen major CFPS reactor formats, from traditional batch systems to advanced platforms. The historical development of CFPS reactors from the 1960s to present day is presented. Additionally, for each format, operational principles, advantages, limitations, and notable applications are …

Performance Enhancement In Rewound Industrial Retrofit Solutions For Five- And Six-Phase Permanent Magnet Assisted Synchronous Reluctance Machines, Kotb B. Tawfiq, Ayman M. El-Refaie, Peter Sergeant, Hatem Zeineldin, Ahmed Al-Durra, Ehab F. El-Sadaany

Electrical and Computer Engineering Faculty Research and Publications

This paper investigates upgrading aging three-phase Permanent Magnet Assisted Synchronous Reluctance Machines (PMaSynRMs) into multiphase configurations—specifically six- and five-phase windings—without modifying the existing stator or rotor laminations. This retrofit supports circular economic principles by extending machine life and reducing material waste and cost. Four configurations are examined: the original three-phase winding, asymmetrical six-phase winding, symmetrical six-phase winding, and five-phase winding. The feasibility of rewinding existing three-phase stators is explored for different slot/pole combinations. Balanced rewound five-phase windings are feasible only when the stator's slot/pole ratio is greater than or equal to 9. Both symmetrical and asymmetrical rewound six-phase windings are …

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. …

A Recycling Route For E-Waste And Aluminium Scrap To Produce A2xxx And A3xx Al Alloys, Iman El-Mahallawi, Shaza Raji, Mayar M. Ali, Mai Mahmoud, Sara Atef, Mahmoud Tash, Serag Salem, Tarek Elmeligy

Mechanical Engineering

Electronic waste (e-waste) generation is significantly escalating, while traditional recycling methods, failing to meet sustainability criteria, are still used. The implementation of sustainability requirements calling for recycling will not be achieved unless intensive research is conducted for mitigating and tolerating the presence of accumulating tramp elements in the recycled alloys and even revising the existing standard specifications. This study explores an innovative approach to recycling electronic waste (e-waste) by integrating it with aluminum scrap through conventional melting techniques to produce high-performance industrial alloys aiming to develop novel aluminum alloys with enhanced properties suitable for various industrial applications. The experimental process …

A Comparative Study Of The Pullout Strength Of Geostraps And Geogrids In Reinforced Soil, Kshitij Gaur, Ashutosh Trivedi, Sanjay Kumar Shukla

Research outputs 2022 to 2026

The sustainable development of geotechnical infrastructure necessitates using durable, efficient, and environmentally resilient reinforcement materials. This study investigates the pullout performance of geostraps to assess their potential as a sustainable alternative to conventional geosynthetics. This study focuses on the pullout performance of geostraps, flexible, polymeric reinforcement materials. There has not been a thorough study of their pullout resistance, which directly affects the stability and durability of reinforced soil structures. Pullout tests were conducted on sandy soil in a controlled environment. The experimental findings from the pullout test were then validated in a numerical model. The model was used to determine …

Electron Beam Irradiation Effects On Bulk Metals And High Entropy Alloys (Crmnv And Crmntiv) And The Synthesis And Characterization Of Irradiation-Induced Damage In Polycrystalline Metal And High Entropy Alloy Thin Films, Najmin Ara Sultana

Mechanical & Aerospace Engineering Theses & Dissertations

Accelerator beam exit windows are designed to withstand intense radiation and mechanical stress while preserving beam transmission and structural integrity. This dissertation explores the structural and mechanical responses of pure metals and high-entropy alloys (HEAs), in both bulk and thin-film forms, under high-dose electron beam (e-beam) irradiation to identify optimal materials for next-generation accelerator exit windows. Monte Carlo simulations using FLUKA, conducted at Jefferson Lab, revealed that amongst Ni, Ti, Cr, and V, Ni exhibits the highest power dissipation, while Ti depicts the lowest power dissipation, with Cr and V demonstrating intermediate characteristics. Bulk polycrystalline (PC) and single-crystalline (SC) samples …

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 …

Performance Characterization And Mechanistic Study Of Dry Process Wr/Sbs Composite Modified Asphalt Mixture, Hongfu Liu, Xiangyang Ren, Wenwen Ge, Zhengwei Yi, Dongzhao Jin, Xinghai Peng, Songtao Lv

Michigan Tech Publications

The dry process modification is characterized by simplicity, flexibility, low energy consumption, and low pollution, making it an ideal choice in pavement repair engineering. This study aims to optimize the use of waste rubber powder and SBS modifiers in dry process composite modification by preparing dry process WR/SBS composite modified particles (WR/SBS CMP) using a twin-screw extruder. The optimum mixing content of modified particles was determined through comparative analysis of pavement performance of dry process WR/SBS composite modified, wet-process SBS-modified, and matrix asphalt mixtures. The rheological properties and modification mechanism of the asphalt binder extracted from these mixtures were tested …

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 …

Impactor Displacement As A Predictor Of Thoraco-Abdominal Organ Injury: Comparison Of Isolated Organ To Whole Body Tests., Jack Seifert, Jared Michael Koser, Alok Shah, Lance Frazer, Frank A. Pintar, Narayan Yoganandan, Dan Nicolella, Brian D. Stemper

Biomedical Engineering Faculty Research and Publications

Purpose

Body armor is used to protect the wearer from penetrating injuries. However, when the armor defeats the projectile, it deforms at high rates into the wearer, referred to as back face deformation (BFD). This deformation can cause a variety of superficial and internal injuries and consequently should be considered when designing body armor. However, current design standards do not adequately consider the effects of BFD, and new data are necessary to inform future design thresholds for BFD. The objective of this study was to develop blunt impact injury risk curves for in vitro thoraco-abdominal organs and determine their applicability …

Advances In Noninvasive Imaging For Detecting Radiation-Induced Lung Injury (Rili), Austen Nissen, Said H. Audi, Anne V. Clough, Brian Fish, Amit Joshi, Meetha Medhora, Jason Walter Sidabras, Heather A. Himburg

Biomedical Engineering Faculty Research and Publications

Purpose: Dr. Richard Hill performed pioneering work in the field of radiation-induced normal tissue injury to the lung including noninvasive imaging studies aimed at identifying imaging biomarkers of radiation-induced lung injury (RILI). RILI is a life-threatening toxicity of radiation exposure relevant to both cancer patients undergoing thoracic radiation therapy (RT) and victims of accidental radiation exposure. The ability to detect RILI noninvasively has the potential to guide treatment planning for RT and, in the case of victims of acute radiation exposures, inform the decision to start mitigative therapies. As part of this special issue of IJRB honoring Dr. Hill’s many …

Designing A Portable And Accessible Diffuse Reflectance Spectroscopy System For Real-Time Detection Of Cervical Intraepithelial Neoplasia, Allison Scarbrough, Diana Moses, Tongtong Lu, Bing Yu

Biomedical Engineering Faculty Research and Publications

Significance: Over 80% of cervical cancer cases occur in lower-to-middle income countries (LMIC’s). This is partly because current screening techniques lack affordability, accessibility, and/or reliability for use in LMIC’s.

Aim: To develop an optical technique for cervical cancer screening that is affordable, accessible, and reliable for use in LMIC’s.

Approach: We developed a portable diffuse reflectance spectroscopy (DRS) system, which costs < $2500 USD to manufacture, and employs a Raspberry Pi to extract the absorption (μ_a) and reduced scattering (μ'_s) coefficients of biological tissue. The system was subject to travel and intentional rough handling. It was further used to capture 320 DRS spectra taken from 64 tissue-mimicking phantoms. Two …

Eco-Friendly Additives For Biodegradable Polyesters: Recent Progress In Performance Optimization And Environmental Impact Reduction, Ahmad Fayyazbakhsh, Nima Hajinajaf, Hamed Bakhtiari, Michael Feuchter, Ilaria Improta, Ehsan Salehi, Sara Kamal Shahsavar, Marketa Julinova, Amirehsan Ghasemi, Bita Ghasemi, Reza Afsharnia, Marek Koutný, Young Cheol Chang

Research outputs 2022 to 2026

Biodegradable polymers have emerged as principal alternatives to petroleum-based polymers, which exert a detrimental impact on the environment. Among these, biodegradable polyesters stand out as particularly noteworthy, renowned for their exceptional properties that find application across diverse industries, including food packaging, biomedical devices, and agriculture. This comprehensive analysis delves into the impact of various additives, with a focus on eco-friendly ones, on biodegradable polyesters, as evidenced by recent research endeavors. The additives are systematically categorized to provide a nuanced understanding within distinct industrial contexts. In the exploration of these additives, a meticulous classification is employed, ensuring a focused analysis of …

Performance Of Interrupted Minichannel Heat Sink Using Various Coolant Fluids, Ernie Mat Tokit, Mohd Zamri Yusoff, Hussein A. Mohammed

Research outputs 2022 to 2026

The advancement in the micro electro mechanical system, MEMS, had been utilized for several years before. This embarked on the compact and high density of power generation for tiny devices. This led to the development of a heat dissipating system for high-power-density devices. Hence, the work intends to simulate the fluid flow performance of interrupted minichannel heat sinks due to the redeveloping and interrupting of the boundary layer merging in previous work that augments the heat dissipation. The study is conducted through numerical work of laminar steady flow, by governing the Navier-Stokes and energy equation. Three interrupted minichannel heat sinks …

Distinctive Transpassivation Behavior And Characteristics Of Passive Films Of Laser Powder Bed Fusion Produced And Annealed Ti–6al–4v In Hank's Solution, Yi Fan Zhang, Liang Yu Chen, Ze Xin Wang, Hong Yu Yang, Maksym Bobrov, Dobuvyy Oleksandr, Yong Liu, Lai Chang Zhang

Research outputs 2022 to 2026

Passivated Ti alloys typically demonstrate enhanced corrosion resistance due to the formation of passive films. Intriguingly, in comparison to the annealed Ti–6Al–4V, laser powder bed fusion (LPBF) produced Ti–6Al–4V exhibits significantly attenuated transpassivation behavior in Hank's solution. This work investigated the electrochemical responses of both samples before and after the transpassivation region to illustrate the underlying mechanism for the phenomenon. In the passivation region, both samples displayed analogous passivation behavior, with the annealed and LPBF-produced Ti–6Al–4V having the current densities of 6.64 × 10⁻⁶ and 8.14 × 10⁻⁶ A cm⁻² at 1 V, respectively. Between 1.5 V …