Engineering Commons^™

Calibration And Validation Of Cyclic Stretching Platform For Stiffness Testing Of Engineered Heart Tissue, Jillian Welsh

Chemical Engineering Undergraduate Honors Theses

Cardiac fibrosis (CF) is a major contributor to the high mortality rate of heart failure which affects over 23 million people worldwide. CF involves cardiac fibroblasts depositing extracellular matrix, made primarily of collagen type I, which stiffens the heart walls over time. As testing new drugs for CF is deterred by the high cost and time required for animal and clinical trials, this research helps to solve the problem by providing an in vitro platform to study fibrosis.

The work involved creating tissues containing human cardiac fibroblast (HCFB) cells. Spring testing was conducted to determine the force applied by the …

Implementation Of A Three-Port Solar Converter With A Battery Energy Storage System, Maison Christopher Phipps

Graduate Theses and Dissertations

The increasing deployment of distributed solar and energy storage systems has created the need for integrated power converters that can efficiently manage photovoltaic (PV) generation, battery energy storage, and grid-tied AC output. This thesis presents the implementation and validation of a 5kW non-isolated Three-Port Converter (TPC) adapted for residential solar applications. The converter consolidates three power stage into a high-frequency, compact architecture: a unidirectional boost converter for PV input, a bidirectional interleaved buck-boost converter for battery energy storage, and a configurable DC/AC inverter for 120Vac single-phase output. The system is controlled using a central controller implemented on a TI C2000™ …

Design And Optimization Of High-Frequency Medium-Voltage Dual Active Bridge Dc/Dc Converter Using Sic Device, Hui Cao

Graduate Theses and Dissertations

High frequency Dual Active Bridge (DAB) converters have become a key enabling technology in medium- and high-power applications such as renewable energy integration, electric vehicle fast charging, and emerging DC power distribution systems. However, when operating at high power and high frequency, DAB converters face critical challenges including limited soft-switching range, uneven semiconductor loss distribution, deadtime-induced resonance, switching-frequency constraints of wide-bandgap (WBG) devices, and transformer DC bias during dynamic transitions. This dissertation addresses these challenges through advancements in modulation strategies and converter architecture. First, an enhanced triple-phase-shift (E-TPS) modulation scheme is proposed to achieve balanced switching and conduction losses across …

Optical Characterization Of Ge And Gesn Grown In Aspect Ratio Trapping Structures For Enhanced Emitter Performance, Abdulla Said Ali

Graduate Theses and Dissertations

Silicon (Si) began dominating the electronics industry since 1960s, the dominance came due to its affordability and well developed fabrication processes. But when it comes to light emitting devices and photonics devices in general, the indirect bandgap of Si has caused many scientists to search for alternative semiconductor materials that can deliver better light emission, materials that can also improve wavelengths detection which is also very limited when it comes to Si, reduce losses and greater light amplification, all this while still being affordable. Despite these limitations, Si has been widely used in Complementary Metal Oxide Semiconductor (CMOS) manufacturing and …

Intrinsic Disinfection Byproducts In Free Chlorine And Chloramine Systems: Formation Of Chlorite, Chlorate, Perchlorate, And Chloronitramide Anion, Julian L. Fairey, Ashley D. Pifer, David G. Wahman

Civil Engineering Faculty Publications and Presentations

Intrinsic disinfection byproducts are formed by reactions between disinfectant species and/or their decomposition products. In this review, we focus on a subset that accumulates in free chlorine and chloramine drinking water systems. First, we review the sequential formation of chlorite, chlorate, and perchlorate in hypochlorite feedstocks. Model simulations indicate chlorate and perchlorate can accumulate under realistic dosing conditions and can be managed with less concentrated feedstocks and climate-controlled storage. Second, we review the formation pathways of dichloramine and chloronitramide anion. Chloronitramide anion accumulation may be mitigated by increasing monochloramine stability and quenching reactive nitrogen species in its formation pathway.

Design And Development Of A Multi-Port Solid State Circuit Breaker Based On Half Bridge Sic Mosfets, Yannal Nawafleh

Graduate Theses and Dissertations

This thesis investigates multi-port solid-state circuit breaker (M-SSCB) architectures that reduce steady-state conduction losses while preserving microsecond-class DC fault interruption and per-port selectivity. The proposed M-SSCB consolidates protection for several node interfaces into a single assembly with shared sensing, control, and a common energy-absorption branch. In normal operation, two electrically symmetric parallel semiconductor paths are established so each port’s current divides approximately in half; because conduction loss scales with current squared, the M-SSCB achieves ≈75% reduction in on-state loss relative to a conventional anti-series SiC path without increasing device count. During fault handling, the coordinated controller detects the local over-current, …

Advanced Membrane Methods For Treatment Of Toxic Contaminants And Education Of Early-Career Researchers, Thomas Mckean Iii

Graduate Theses and Dissertations

Membrane technologies are attractive as they are linearly scalable and often require lower operating costs compared to other technologies. One area where they are particularly effective is the treatment of water contaminated with toxic substances. The simplicity of this removal mechanism provides reliable performance capable of meeting stringent removal requirements. However, membrane fouling is a major challenge that often limits their commercial viability. This research sought to investigate novel approaches to pretreatment and membrane modification to overcome fouling and high operating pressures. In addition, membrane separation processes can often be developed into simple yet educational experiments that are ideal for …

Optimal & Robust Control Of A Bidirectional Dc-Dc Converter In Ev Systems, Yasser Ayeva

Electrical Engineering and Computer Science Faculty Publications and Presentations

This paper analyzes the performance of PI, LQR, and H∞ controllers for the regulation of a bidirectional buck boost converter in electric vehicle systems. To get the system state space equations, a continuous conduction average model is linearized. For analysis a PI controller will be used as baseline, the LQR controller will be used to improve transient response, and the H∞ controller will be used for the system robustness and disturbance rejection. The simulation results show that the advanced controllers surpass the PI controller in terms of overshoot, settling time, and voltage ripple, with the H∞ controller offering the best …

Series Resonant Converters With Medium Voltage Sic Mosfets For Electric Aircraft Applications, Xinyuan Du

Graduate Theses and Dissertations

To develop high-performance high- power-density MV power converters, the emerging silicon carbide (SiC) devices are more attractive than their silicon (Si) counterparts, since the fast switch frequency brought by the SiC can effectively reduce the volume and weight of the filter components and thus increase the converter power density. From the converter topology perspective, with the MV dc distribution, the single stage isolated dc/dc converter are suitable for next-generation electric aircraft system due to soft switching and high power density. In this work, comprehensive static and dynamic characterizations were conducted for the latest 6.5 kV silicon carbide (SiC) MOSFETs from …

Design Of Phase Shifter And True Time Delay Gan Mmics For High-Temperature Ku-Band Applications, Michael Lee Thompson

Graduate Theses and Dissertations

This thesis presents the design, implementation, and high-temperature characterization of Gallium Nitride (GaN) monolithic microwave integrated circuits (MMICs) developed for beamforming and phased-array systems operating in the Ku-band (12-14 GHz). Two integrated circuits were designed: a 3-bit digital phase shifter and a 3-bit true time delay (TTD), both optimized for high linearity, low insertion loss, low phase error, and stable operation at elevated temperatures up to 300°C. Developing both a phase shifter and a TTD enabled a direct comparison of their beamforming performance and the evaluation of beam squint effects over frequency, a critical factor in wideband array design. The …

Experimental Characterization Of An Additively Manufactured Porous Gyroid Air-Cooled Heat Sink, Grant S. Resler

Mechanical Engineering Undergraduate Honors Theses

This paper presents the development of a ducted test facility designed to evaluate heat sinks efficiency at varying air velocities. This enables the evaluation of both heat transfer and pressure drop performance. These metrics are essential to the overall efficiency of heat sinks and help identify the optimal air velocity to achieve the desired thermal performance. A standard plate fin heat sink was used as a control for comparison to a novel heat sink. The specialized heat sink geometry was generated using nTop, a generative design software focused on additive manufacturing. This design was fabricated via Direct Metal Laser Sintering …

Solar Powered Conservation: The Effects Of Solar Photovoltaic Facilities On Avian Community Composition, Michael Christopher Ferrara

Graduate Theses and Dissertations

The expansion of solar photovoltaic energy infrastructure is transforming landscapes worldwide. Increasingly, facilities are planted with native vegetation, yet how vegetation characteristics and landscape variables shape wildlife communities in solar facilities remains poorly understood. Because avian populations have been in decline and are sensitive to habitat changes, understanding how solar facilities influence avian communities is important. In Chapter 1, we used autonomous recording units, local vegetation measurements, and land use and land cover data to quantify how avian community occupancy is influenced by solar cover in solar facilities and comparable reference sites. We used a Bayesian multi-species occupancy model to …

Volume Status Detection With Integral Pulse Frequency Modulation Model Of Peripheral Venous Pressure, Jeremiah Rhys Wimer

Graduate Theses and Dissertations

This thesis studies the effectiveness of utilizing a modified integral pulse frequency modulation (IPFM) algorithm to synthesize peripheral venous pressure (PVP) waveforms for the detection of several physiological conditions using logistic regression. PVP waveforms are collected from 18 human patients and 4 porcine subjects. Human data are used to train models for determining the hypovolemic status of the patient, while the porcine data are used to train models for determining level of anesthesia and detecting internal hemorrhaging. In the human dataset, the waveforms collected from the 18 patients are classified into two groups according to serum chloride levels: resuscitated (≥100 …

Deep-Learning-Enhanced Automated Coherent-Light Diffraction System For High-Speed, Highly Accurate Strain-Specific Foodborne Bacterial Recognition, Yang Tian, Ziyu Liu, Yinuo Huang, Ramesh Bahadur Bist, Yiting Xiao, Samantha Marrianne Howe, Tsung Cheng Tsai, Terry Howell, Jeyam Subbiah, Michael L. Looper, Dongyi Wang

Biological and Agricultural Engineering Faculty Publications and Presentations

Rapid, accurate differentiation of bacterial pathogens at both species and strain levels is critical for clinical diagnostics, food safety, and epidemiological surveillance. We report a fully automated laser-diffraction platform that achieves rapid, label-free identification of bacterial pathogens at both species and strain levels. The system integrates dual cameras, an automated X-Y stage, and deep-learning classifiers to deliver sub-second, nondestructive diagnostics without reagents or culture. Using diffraction patterns from eight strains, including Escherichia coli O157:H7, K12, ATCC 25922, F18, Salmonella enterica, Listeria monocytogenes, Listeria innocua, and Staphylococcus aureus, a custom YOLO11x model attained 100 % Top-1 accuracy under five-fold stratified cross-validation …

Unraveling Nucleation Mechanisms In Membrane Distillation: A Molecular Dynamics And Enhanced Sampling Approach, Nazanin Abbasi

Graduate Theses and Dissertations

Membrane distillation offers a promising route for desalination but remains limited by salt scaling, where mineral crystals nucleate and grow in concentrated brines. To inform strategies that mitigate scaling, this thesis investigates homogeneous nucleation in supersaturated aqueous NaCl solutions using molecular dynamics and enhanced sampling techniques. Several collective variables (CVs) are tested to capture the early stages of ion aggregation and crystal formation, including ion–ion coordination number, dehydration, and bond orientational order parameters Q₄ and Q₆. Enhanced sampling techniques, such as metadynamics and umbrella sampling, are employed to overcome the high free energy barriers associated with the formation of critical …

Extending Touch: Investigating Sensorimotor Integration, Cognitive Workload, And Presence With Neuro-Haptic Feedback In Virtual Reality, Aliyah Khadijah Shell

Graduate Theses and Dissertations

Sensory feedback from the hand is fundamental for the coordination of fine motor skills and overall sensorimotor function. Impaired somatosensation during task execution has been associated with the development of inaccurate motor plans, which can hinder motor learning. Virtual Reality (VR) has emerged as a promising tool for motor rehabilitation; however, most VR-based interventions overlook the critical role of tactile feedback in motor control. The absence of touch feedback, which is integral to conventional rehabilitation and training, may limit the full therapeutic potential of VR. Integrating functionally relevant neurostimulation based haptic feedback (neuro-haptic feedback) into VR-based interventions may enhance functional …

Design And Testing Of A Gallium Nitride Power Amplifier For High-Temperature Radar Applications, Walker Landry Harbison

Graduate Theses and Dissertations

This thesis offers the design, fabrication, and evaluation of a gallium nitride (GaN) power amplifier integrated circuit (IC) intended for high-temperature radar applications. Radar systems are used in many different applications, such as defense, aerospace, and weather. For their function, these systems require high power, efficiency, and reliability under a wide range of operating conditions. Taking advantage of the material properties of GaN, including its high breakdown voltage, wide bandgap, and thermal conductivity bolstered by the use of silicon carbide in the substrate, this work focuses on examining amplifier performance in both ambient and elevated temperature conditions. The PA was …

Learning To Accelerate Tightening Of Convex Relaxations Of The Ac Optimal Power Flow Problem, Faith Cengil, Harsha Nagarajan, Russell Bent, Sandra Eksioglu, Burak Eksioglu

Industrial Engineering Faculty Publications and Presentations

We propose a novel machine learning (ML)-based approach to significantly reduce the run times of the optimality-based bound tightening (OBBT) algorithm for strengthening the convex relaxations of the non-convex Alternating Current Optimal Power Flow (AC-OPF) problem. While OBBT can yield near-global solutions via tight convex relaxations, its runtime remains a critical bottleneck on large-scale power grids. Our key contribution is a dynamic policy that selects smaller subsets of voltage magnitude and phase-angle difference variables for sequential bound tightening at every iteration of the OBBT algorithm. This ensures that the bound-tightening process remains adaptive, thereby circumventing the stalling in the optimality …

Automation And Upgrading Of Custom Cold Wall Uhv-Cvd Reactor For Group Iv Material Development, Alexander Golden

Graduate Theses and Dissertations

Group IV alloys have shown promising results for infrared optoelectronic applications where III-V materials are currently dominant. The III-V material system has vacancies that Group IV materials can fill, most importantly complementary metal oxide semiconductor (CMOS) process compatibility making quality devices much cheaper and widely available compared to the current state of the art. Silicon, being an indirect band gap Group IV material, has poor performance in optoelectronic applications but is the dominant material for most of the electronic industry. However, when silicon is alloyed or substituted with other group IV materials, these optoelectronic properties can be enhanced and, in …

Investigating The Efficiency Of Ingan P-N-P-N Homojunction Solar Cells, Moath Alhejji, Mohammad Alavijeh, Jacob Kupernik, Mirsaeid Sarollahi, Abbas Jammali, Seyed Taghavi, Reem Alhelais, Md Hel Uddin Maruf, Morgan Ware

Electrical Engineering and Computer Science Faculty Publications and Presentations

This research investigates the development of a novel p-n-p-n homostructure solar cell, through semiconductor simulations using the Nextnano software. InGaN was used as a model system in order to achieve a bandgap with optimized efficiency for a p-n homojunction solar cell. By increasing the uniform doping concentration from 1.5*10(16) cm(-3) to 1.5*10(17) cm(-3), the open circuit voltage (V-oc) increased while the short-circuit current density (J(sc)) decreased, as expected in simple p-n junctions. The p-n-p-n structure achieved a peak efficiency of 32.91% at a doping level of 6.5*10(16) cm(-3), a similar to 7% improvement over a conventional p-n junction's 25.31% efficiency …

Cytotoxicity And Genotoxicity Of Glyphosate And Roundup Quickpro On Chinese Hamster Ovary Cells, Tasnimul Ferdous, Qingfang He, Wen Zhang

Civil Engineering Faculty Publications and Presentations

Glyphosate and Roundup products have become the most used herbicide worldwide. However, previous bans in Europe and recent reversal have caused confusion over their safety. This study aims to investigate the cytotoxic and genotoxic effects of Roundup QuickPro and its main ingredient glyphosate using Chinese hamster ovary (CHO) cells. Cytotoxicity was calculated by measuring CHO cell viability with 72 h of exposure to each toxicant. Roundup QuickPro exhibited higher cytotoxicity with LC50 of 511.2 mu g/mL than glyphosate's LC50 of 3389 mu g/mL. The recommended application concentration (11,233.7 mu g/mL) of Roundup QuickPro is much higher than the measured LC50, …

Machine Learning Model For Detecting Masked Hypertension In Young Adults, Brendyn Miller, Samuel Coeyman, Annemarie Wentzel, Carina M.C. Mels, William J. Richardson

Chemical Engineering Faculty Publications and Presentations

Introduction Cardiovascular disease (CVD) remains the leading global cause of mortality, with hypertension (HT) being a significant contributor, responsible for 56% of CVD-related deaths. Masked hypertension (MHT), a condition where patients exhibit normotensive blood pressure (BP) in clinical settings but elevated BP in out-of-clinic measurements, poses an elevated risk for cardiovascular complications and often goes undiagnosed. Current diagnostic methods, such as ambulatory BP monitoring (ABPM) and home BP monitoring (HBPM), have limitations in feasibility and accessibility. Methods This study aimed to address these challenges by leveraging machine learning (ML) models to predict MHT based on clinical data from a single …

Novel Electroactive Polymer Actuators Using All-Polyelectrolyte Poly(Ionic Liquid) Ionogels, Kayla Foley, Iwei Chu, Keisha B. Walters

Chemical Engineering Faculty Publications and Presentations

Poly(ionic liquid)-based ionogels are excellent all-poly(electrolyte) candidates for electroactive actuation applications, but investigation of their actuation behavior and ionogel properties has largely been limited to styrenic block copolymers. In this work, ionogels were prepared from a novel poly(ionic liquid) (PIL) block copolymer, poly[(2-dimethyl amino) ethyl methacrylate)]-block-poly[4-vinylbenzyl-3-butyl imidazolium bis(trifluoromethylsulfonyl)imide] (PDMAEMA-b-PVBBImTf(2)N) combined with an ionic liquid, 1-butyl-3-methyl imidazolium tetrafluoroborate (C(4)C(1)ImBF(4)), at weight percentages between 0 to 40 wt%. Under a low applied voltage (4 V DC) microscale actuation was achieved for films prepared from the neat PDMAEMA-b-PVBBImTf(2)N block copolymer, as well as its corresponding 10 wt% ionogel; this result critically expands the …

Optimizing Driving Waveforms To Enhance Inkjet Printing Speed, Chao Jan Sui, Wenchao A. Zhou

Mechanical Engineering Faculty Publications and Presentations

Inkjet printing has been extensively employed across various industrial applications due to its capability to produce high-resolution outputs and accommodate a diverse range of materials. However, its printing speed (volumetric printing rate or volumetric productivity) has remained a bottleneck for large-scale manufacturing. This study introduces a new strategy aimed at enhancing the speed of piezoelectric inkjet printing by optimizing waveform parameters. Expanding on our prior work, which analyzed the relationship between driving signal parameters and key factors like droplet volume and jetting frequency, we now focus on optimizing these parameters to maximize printing speed. To establish a fair comparison across …

Electromigration In Eutectic Gold-Tin (80au20sn-Wt%) Solder Joints, Whit Vinson, David Huitink

Mechanical Engineering Faculty Publications and Presentations

Eutectic gold-tin solder joints (80Au20Snwt%) with a diameter of 300 mu m diameter were subjected to electromigration (EM) conditions of 10,000-20,000 A/cm2 in the ambient temperature range of 125-215 degrees C. The present work examines a set of 36 experimental test runs using two different test coupons (18 runs with each coupon type and a total of 90 joints tested). Seven of the 36 coupons survived the maximum test duration period of 500 h. One coupon type created a linear electric current pathway through two lengths of 254-mu m-diameter copper wire connected by a single gold-tin joint. The other coupon …

Fabrication Of Multimodal Anion Exchange Membrane For Chromatographic Purification Of Full Adeno-Associated Viral Capsids, Xiaolei Hao, Sumith Ranil Wickramasinghe, Xianghong Qian

Biomedical Engineering Faculty Publications and Presentations

A multi-modal anion exchange ligand 2-methyl-phenylimidazole has been successfully functionalized on highly porous electrospun regenerated cellulose membrane substrate for the separation of full and empty adeno-associated viral (AAV) capsids. The functionalized membrane has an average pore size of 0.5 mu m and exhibits both charge and hydrophobic functionality. The ligand is able to distinguish the subtle physio-chemical differences between the full and empty viral capsids. The multi-modal anion exchange membrane is able to separate the full capsids from affinity-captured mammalian AAV2 using both gradient and two-step elution methods with superior performance. A full capsid recovery of 72.9% at 85.3% purity …

Characterizing Piezoelectric-Blended Polydimethylsiloxane For Use As A Mechanoelectrical Responsive Cell Culture Substrate, Alexis P. Applequist, Lance D. Cordes, Lais A. Ferreira, Kartik Balachandran

Biomedical Engineering Faculty Publications and Presentations

In this study, we developed a piezoelectric-polydimethylsiloxane (pz-PDMS) composite by blending poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) with PDMS to create a biocompatible, mechanoelectrical responsive material. The pz-PDMS was synthesized with varying piezoelectric concentrations (0%, 1%, 3%, and 5%) and characterized for visual properties, mechanical properties, mechanoelectrical sensitivity, and biocompatibility. Compression testing showed no significant change in mechanical strength with the addition of piezoelectric particles, while mechanolectrical sensitivity testing revealed a non-linear increase in voltage response, with 5% pz-PDMS producing the highest sensitivity. Fatigue testing demonstrated no change in sensitivity after 7 days of cyclic displacement. Additionally, microcantilever experiments demonstrated the high fidelity …

Interface And Mechanical Properties Of 1d And 1d-2d Carbon Nanomaterials In Copper Matrix, Abigail L. Eaton, Arun K. Nair

Mechanical Engineering Faculty Publications and Presentations

Low-dimensional carbon nanomaterials have unique electron density distributions which warrant their classification as 1D and 2D, and they are useful for a wide variety of nanocomposite applications. This group includes 1D carbyne, which has high stiffness, and a 1D-2D hybrid composed of carbyne and a highly elastic cyclo[18] carbon ring (2D). We use density functional theory and molecular dynamics methods to study the interface properties of carbyne and the hybrid on Cu (111) surface and determine the mechanical properties of nanocomposites comprised of the nanomaterials as a fiber in Cu matrix at varying temperatures. We predict that on Cu (111) …

Harvesting Aav By Tangential Flow Filtration Using Reverse Asymmetric Membranes, Xiaolei Hao, Ronny Horax, Xianghong Qian, April Wheeler, Hironobu Shirataki, Sumith Ranil Wickramasinghe

Chemical Engineering Faculty Publications and Presentations

Efficient bioreactor clarification for harvesting virus particles is often challenging. Tangential flow filtration is attractive as it can be easily adapted for batch and perfusion operations. Here the feasibility of using reverse asymmetric hollow fiber membranes, where the more open support structure faces the feed stream, has been investigated for harvesting adeno associated virus serotype 2. The open support structure of these membranes stabilizes a secondary membrane consisting of rejected particulate matter. It is essential that the stabilized secondary membrane remains highly permeable. Flux stepping experiments were conducted in total recycle mode in order to determine the critical flux. The …

A Radiation-Hardened 4-Bit Flash Adc With Compact Fault-Tolerant Logic For Seu Mitigation, Fnu Naveed, Jeff Dix

Electrical Engineering and Computer Science Faculty Publications and Presentations

This paper presents a radiation-hardened 4-bit flash analog-to-digital converter (ADC) implemented in a 22 nm fully depleted silicon-on-insulator (FD-SOI) process for high-reliability applications in radiation environments. To improve single-event upsets (SEU) tolerance, the design introduces a compact fault-tolerant logic scheme based on Dual Modular Redundancy (DMR), offering reliability comparable to Triple Modular Redundancy (TMR) while using two storage nodes instead of three, and a simple XOR-based check in place of a majority voter. A distributed sampling architecture mitigates SEU vulnerabilities in the input path, while thin-oxide devices are used in analog-critical circuits to enhance total ionizing dose (TID) resilience. Post-layout …