Engineering Commons^™

Atomic-Scale Simulation Of Dissipation And Adhesion During Interactions Between Mineral Surfaces, Baochi Doan

Electronic Theses and Dissertations, 2020-2023

Adhesion and dissipation during surface interactions are important phenomena with wide applications in materials science, including cold-spray technology for additive manufacturing and stiction in MEMS (Mircro ElectroMechanical Systems). In planet formation theories, energy dissipation in collisions between mineral grains is important to the formation of dust-grain aggregates and planetesimals. Early contact mechanics theories such as Hertz and Johnson-Kendall-Roberts have laid theoretical foundations for understanding these phenomena. Recently, there are breakthroughs in using non-equilibrium thermodynamics methods to elucidate dissipation. For example, the Green-Kubo method can calculate transport coefficients based on the Fluctuation-Dissipation theorem, and Jarzynski equality can be used to determine …

Exergoeconomic Analysis And Optimization Of Novel Cogeneration Systems For Freshwater Production, Power And Cooling, Sattam Alharbi

Electronic Theses and Dissertations, 2020-2023

Global consumption of energy and freshwater is increasing continuously due to population growth and improving living standards. The world energy consumption is anticipated to increase by around 50% by 2050 according to the U.S Energy Information Administration (EIA). There is also very limited access to freshwater and cooling in many developing countries. Therefore, developing an efficient energy system, recovering the waste heat (cogeneration system or multigeneration) to produce freshwater and cooling, and using a renewable energy source are promising solutions to meet the energy demand and to reduce environment pollution associated with fossil fuels. In this study, several novel cogeneration …

Processing Of 3d Porous Biomaterial Scaffolds To Enhance The In Vitro Breast Cancer Tumor Microenvironment, Zi Wang

Electronic Theses and Dissertations, 2020-2023

Tumors contain heterogeneous cell populations within the tumor microenvironment (TME). TME supports tumor progression and development via the function of multiple cell types and cell-extracellular matrix (ECM) interactions. 3D porous biomaterial scaffolds can be a type of in vitro tumor models to mimic TME ECM. Current tumor models lack structural complexity replicating tumor ECM, tunable mechanical properties, and have limited mass exchange between cells and their microenvironment. In this work, we firstly developed scaffolds with a hierarchical pore structure via the Freeze-FRESH(FF) fabrication technique that combines 3D printing and freeze-casting. Later, we studied the effect of varying processing parameters and …

Fabrication Of High-Frequency Piezoelectric Resonant Micro-Accelerometers Based On Capacitive Loading Effect, Ankesh Todi

Electronic Theses and Dissertations, 2020-2023

In this thesis, a high-frequency resonant accelerometer is presented. This novel sensor was designed to operate in 10's of MHz frequency range utilizing an out-of-plane capacitive mechanism for acceleration sensing. The sensor is comprised of a 2-port RF MEMS piezoelectric resonator, operating at 27MHz, and a Capacitive Mass-spring structure. One of the resonator ports is electrically connected to the variable capacitor in the mass-spring structure. The acceleration is measured utilizing a piezoelectric stiffening mechanism, where a change in the termination impedance of a piezoelectric resonant body would result in a shift in the resonance frequency of the resonator. The acceleration …

Model-Form Uncertainty Quantification In Prognosis And Fleet Management With Physics-Informed Neural Networks, Arinan De Piemonte Dourado

Electronic Theses and Dissertations, 2020-2023

Prognosis and health management play an important role in the control of costs associated with the operation of large industrial equipment. By properly comprehending hardware degradation and accurately predicting the remaining useful life of such equipment, we can significantly lower operational costs by reducing asset downtime and maintenance interventions. However, complex interactions between operational conditions and component capability make accurately modeling damage accumulation for large fleets a daunting task. Unforeseen factors such as aggressive missions introduced by operators, exposure to harsh environments, manufacturing issues, amongst many others, can lead to large discrepancies between predicted and observed useful life. Motivated by …

Parameter Calibration And Optimization In Smart Grid For Synchronous Generators And Converters, Seyyed Rashid Khazeiynasab

Electronic Theses and Dissertations, 2020-2023

In power systems, monitoring, protection, and control are usually model based; an accurate dynamic model for either synchronous generators or power electronic converters is essential. Besides, renewable energies, smart loads, energy storage, and new market behavior add new sources of uncertainty to power systems. Therefore, planning in real-time and developing high-quality models is crucial to adapt to uncertainties. In this thesis, we propose a framework for validating and calibrating power system models using novel methods. At the first step, we developed the nonlinear sensitivity-based method to find the critical parameters. Then, we propose an Approximate Bayesian Computation (ABC) based method …

Dynamic Analysis Of The Implementation Of The Blockchain Technology In The Supply Chain, Rehab Ali

Electronic Theses and Dissertations, 2020-2023

Blockchain technology is a new digital technology that has been disrupting the way businesses are performing. It is a decentralized and distributed ledger that enables transactions of any form of value. As blockchain technology provides visibility, transparency, and security through the multi-agent system, the supply chain sector is one of its critical and promising applications. In a highly dynamic environment, the supply chain's efficiency needs to be measured from a blockchain perspective. As the main benefit of blockchain technology is the visibility and real-time access to data, blockchain technology's preeminent affected areas within the supply chain are the responsiveness to …

Evaluating Source Water Quality, Pretreatment, And Particulate Mass Transport In A Nanofiltration Membrane Process, Courtney Powell

Electronic Theses and Dissertations, 2020-2023

This document details the source and occurrence of particulates in a nanofiltration (NF) process, considers the implementation of additional pretreatment to improve feedwater quality, and investigates the impact of submicron particles on membrane performance. Much of this research was performed in cooperation with the City of Boynton Beach (City) at the West Water Treatment Plant (WTP) and stemmed from particulate fouling concerns in the pretreatment and NF membrane processes. The water quality of the individual wells that supply the West WTP was evaluated to identify the source of particulates which overload the pre-filters (5-μm cartridge filters) and may contribute to …

The Effect Of Polyelectrolyte Modification Of Ultrafiltration Membranes On Fouling Resistance And Rejection Of Contaminants Of Emerging Concern, Kunal Olimattel

Electronic Theses and Dissertations, 2020-2023

This research attempted to leverage the unique properties of poly (allylamine hydrochloride) (PAH)/poly (acrylic acid) (PAA) bilayer coatings to enhance antifouling and antimicrobial properties of a commercially available ultrafiltration (UF) membrane as well as the removal of PFOA and PFOS—the two CECs that most frequently represent the class of PFAS. The effects of selected water matrix components (humic acids [HA] and cations) on PFOA and PFOS removals were also investigated when using the functionalized membrane. PAH/PAA films were first deposited on the membrane using a fluidic layer by layer (LbL) technique and then crosslinked, followed by embedding of the silver …

Hotspot Cooling Performance For Confined Jet Impingement Cooling, Tanvir Ahmed Chowdhury

Electronic Theses and Dissertations, 2020-2023

The current trend in microelectronics is to manufacture devices with increased computational powers and reduced size. These devices with increased power densities are consequently subject to extreme thermal loads. Thermal management of these power loads is extremely challenging. The presence of the hotspots can make this challenge even more difficult. Jet impingement cooling is one of the top candidates for removing such extreme heat fluxes in microelectronics. Jet impingement cooling can achieve heat transfer coefficients (HTCs) due to its normal incident flow-field and ability to thin the local thermal boundary layer in the stagnation region. This dissertation presents the hotspot …

Remediation Of Roadway Runoff Nutrients: Querying Sources Delivery Mechanism, Efficacy Of Stormwater Best Management Practices, And Stormwater Routing Through Karst Geology, Mohammad Shokri

Electronic Theses and Dissertations, 2020-2023

Stormwater road runoff is a widespread non-point source of contaminants such as nutrients, which endangers water bodies, especially in vulnerable karst areas such as Florida. While roadside vegetated filter strips (VFSs) and stormwater basins are generally accepted best management practices (BMPs) for stormwater management, uncertainties about VFS nutrient removal are reported and stormwater basins are concerned of facilitating contaminant transport. In this dissertation, the application and efficacy of engineered infiltration media was tested as a subgrade for the enhanced nutrient removal from roadway runoff. Results of field-scale laboratory testing indicated that a VFS with engineered biosorption activated media (BAM) outperformed …

Ultraviolet Solar Blind Ga2o3-Based Photodetectors, Isa Hatipoglu

Electronic Theses and Dissertations, 2020-2023

Detection within the deep ultraviolet (DUV) region (˜200-280 nm) offers unique fundamental advantages to probe certain optical traces. Therefore, many applications have emerged including flame and missile detection, and non-line of sight and space-to-space communication. Ga2O3 has become a natural choice for DUV detection owing to its intrinsic ultra-wide optical bandgap (˜4.85 eV), extrinsic n-type dopability, and excellent chemical and physical stability. However, Ga2O3 has no viable p-type doping to date, and fabricated photodetectors show only partial coverage of the entire solar-blind region (˜200-245nm). Furthermore, there is a limited understanding of how various growth parameters for ß-Ga2O3 and its alloys …

Microstructural Development Of Inconel 625 Nickel-Based Superalloy As Function Of Laser Powder Bed Fusion Parameters, Sofia Nucci

Electronic Theses and Dissertations, 2020-2023

Additive manufacturing (AM) allows fabrication of complex components with features that are impractical or impossible to achieve through conventional methods. Selective laser melting (SLM) powder bed fusion AM technology was selected for this study on Inconel 625, a widely utilized high-temperature alloy that is hard to machine. The present work investigates impact of laser power and scanning speed variations on the resulting characteristics of fabricated IN625 samples. Gas atomized metallic alloy powders were acquired and analyzed through laser diffraction to verify acceptable size distribution. Cubic samples were built with a range of laser scan speeds in 200 mm/s intervals for …

Data-Driven Analysis For Integrated Transmission And Distribution Systems With High Penetration Of Distributed Energy Resources, Inalvis Alvarez-Fernandez

Electronic Theses and Dissertations, 2020-2023

With the high penetration of inverter-based distributed energy resources (DERs), network situational awareness is a challenge for both transmission and distribution (T&D) system operators and planners. It is becoming increasingly important to equip transmission planners with the visibility of DER dynamic performance in distribution systems. Not having visibility of the disconnection of DERs with the occurrence of transmission events, could result in an erroneous view of the stability of bulk power system. The aggregated distributed energy resource (DER_A) model is able to model the aggregated dynamic response of inverter-based DERs in distribution circuits. The parameterization of DER_A model requires extensive …

Characterization Of Hydrogenated Boron Carbide And Boron Carbon Nitride Thin Films And Applications, Shraddha Dhanraj Nehate

Electronic Theses and Dissertations, 2020-2023

Dimension scaling has been the driving force for improved performance of semiconductor integrated circuits (ICs) for the past few decades. While the semiconductor industry continues to achieve returns on Moore's law, the resistance-capacitance (RC) delay remains a critical bottleneck towards further performance improvement. To support advanced computing performance, the development and integration of new low dielectric (low-k) materials to reduce the capacitance of interconnects are crucial. Apart from the low dielectric constant value, one of the other vital parameters to replace the current dielectric material is mechanical stability. Materials in the boron, carbon, and nitrogen ternary triangle have emerged promising …

Atomically Thin Platinum-Based Dichalcogenide Materials For Multifunctional Photo-Sensitive Applications, Mashiyat Sumaiya Shawkat

Electronic Theses and Dissertations, 2020-2023

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are a distinct class of atomically thin materials assembled by weak van der Waals bonding. They exhibit 2D layer number-dependent bandgap tunability promising exciting applications in electronics and optoelectronics. Among them, there is a surge of interest in Platinum-based dichalcogenides (e.g., PtSe2 and PtTe2). 2D PtSe2 has a theoretically predicted carrier mobility of > 1000 cm2/(Vs), at room temperature, which is higher than that of most 2D TMDs. Additionally, 2D PtSe2 exhibits a semiconducting to metallic transition with an increasing number of layers. 2D PtTe2 is highly metallic in its few- layer form and exhibits …

Harvesting Heat From Safer, Energy-Dense Slow Pyrolant Mixtures For Future Space Missions, Katerina Chagoya

Electronic Theses and Dissertations, 2020-2023

Energy sources powering space missions range from highly energetic nuclear reactions to short-lifetime and low-output batteries. The proper selection of a power system is dependent on the mission duration and destination and oftentimes energy sources that may be optimal for the former may be unsuitable for the latter. Various limitations of these power sources hinder the capacity for regular and frequent space exploration. However, the ability to harvest heat for electrical power generation would allow for long-distance and long-duration missions at a reduced cost. By employing a regulated, self-propagating, exothermic chemical reaction between solid fuel and oxidizer, we hope to …

Improving Performance And Flexibility Of Fabric-Attached Memory Systems, Vamsee Reddy Kommareddy

Electronic Theses and Dissertations, 2020-2023

As demands for memory-intensive applications continue to grow, the memory capacity of each computing node is expected to grow at a similar pace. In high-performance computing (HPC) systems, the memory capacity per compute node is decided upon the most demanding application that would likely run on such a system, and hence the average capacity per node in future HPC systems is expected to grow significantly. However, diverse applications run on HPC systems with different memory requirements and memory utilization can fluctuate widely from one application to another. Since memory modules are private for a corresponding computing node, a large percentage …

Factors That Affect The Successful Implementation Of Quality Management Systems In Healthcare, Mustafa Rawshdeh

Electronic Theses and Dissertations, 2020-2023

Modern Organizations must be high performing to sustain and grow their operations. This is particularly true for healthcare organizations as they have complex and sensitive operations. One way to improve organizational performance is to adopt Quality Management Systems (QMSs). QMSs organize and improve the effectiveness of all processes to meet stakeholder requirements and achieve organizational performance improvements in alignment with strategic goals. However, the value of QMSs is dependent on successful implementation, which is reportedly quite challenging. This doctoral research examines the factors that affect the successful implementation of QMSs in healthcare. First, a systematic analysis of the published literature …

Mechanics Of Low Dimensional Biomimetic Scale Metamaterials, Hossein Ebrahimi

Electronic Theses and Dissertations, 2020-2023

Combination of topology and material could play an important role in giving rise to nontraditional behavior in mechanical structures and is a typical strategy in nature. Topology is concerned with the geometrical and spatial properties of the objects, which are preserved under continues mechanical deformation of the object such as stretching, bending, twisting, etc. In this work, we focus on structures based on fish scale inspired surface topology. The utilized idea for surface topology is a bioinspired design on the substrate of biological scale-covered systems. Scales are a path breaking evolutionary adaptation that accompanied vertebrate evolution for the past 500 …

Heart Rate Variability In Adults During 24-Hours With A Focus On Sleep Period, Ankur Ravikanth

Honors Undergraduate Theses

The objective of this study is to investigate heart rate variability (HRV) over a period of 24 hours with special focus on patterns during the sleep period. Comparisons were made between sleep and the full 24-hour data. The Polar M430 watch was used to record heart rate (HR) data for about 24 hours, and the subject kept a journal of the activities they performed throughout the day. The data was visualized as heart rate in beats per minute (BPM) as a function of time. To check the accuracy of the Polar watch, a 7-minute recording of HR from the watch …

Experimental Study Of A Liquid Fuel Bluff Body Flame At Elevated Pressures, Karam Paul

Honors Undergraduate Theses

The purpose of this research was to operate a bluff body flame holder with the objective of stabilizing a flame at elevated pressures over a range of equivalence ratios. The ability to have a ground-based test rig capable of maintaining stable flames at high pressures and temperatures is critical in understanding flames present in modern jet engines and gas turbine technologies. The facility was reconfigured multiple times and the resultant flame was imaged within the optical test section. A converging nozzle was utilized to choke the flow and vary the operating pressures up to 5 atm. By regulating mass flow …

Electromyographic And Mechanomyogrpahic Signal Changes With Fatigue In Adults, Rehana Koilpillai

Honors Undergraduate Theses

Surface electromyography (sEMG) and mechanomyography (MMG) are well-studied signals that can reveal information about the physiological behavior of muscles during contraction. The purpose of this study was to quantify, characterize, and analyze the electrical and mechanical muscle responses to submaximal, isometric contractions in the rectus femoris in adults. Previous studies have investigated the use of EMG to monitor muscle fatigue. However, more information appears to be needed about the use of MMG to measure muscle fatigue during submaximal isometric contraction in the rectus femoris. In this study, the utility of MMG as a measure of muscle fatigue or muscle state …

Flow Field Dynamics As A Result Of Perforated Plates, Hector Perez

Honors Undergraduate Theses

Detonation to Deflagration Transition (DDT) is the process of accelerating a laminar flame to supersonic speeds to cause a detonation. A method used to reach Chapman-Jouguet (CJ) detonation velocities is the induction of turbulence to increase the surface area of the flame front, increasing the consumption rate of unburned gases and the propagation speed of the flame. Perforated plates helped achieve flame acceleration in previous studies to induce turbulence when the flame front interacts with the turbulator; previous work also accomplished detonation speeds with perforated plates. This work aims to visualize the flame front and perforated plate interaction and analyze …

Motor Control System For Near-Resonance High-Cycle Fatigue Testing, Samer K. Armaly

Honors Undergraduate Theses

This research project develops a low-cost high-cycle fatigue (HCF) testing system comprised of an AC motor, variable frequency drive (VFD), eccentric cam, and feedback controller. The system acts as a forced harmonic oscillator leveraging mechanical resonance to vibrate a specimen at a frequency required to induce the testing's strain amplitudes.

This system depends highly on the material being tested. As such, the controller incorporates material characteristics. A frequency sweep measures the strain amplitude to characterize the specimen. Additionally, other measurements such as acceleration can be used as a proxy control variables for strain. A function converts the control variable to …

Influence Of Ecm Composition And Intracellular Calcium On Endothelial Biomechanics And Prediction Of Cellular Stresses Using Machine Learning, Vignesh Aravind Subramanian Balachandar

Electronic Theses and Dissertations, 2020-2023

Endothelial cells, which form the inner layer of the vasculature, constantly interact with their external microenvironment called the extracellular matrix (ECM) by exerting contractile cell-substrate stresses called tractions and cell-cell stresses called intercellular stresses. This cellular mechanosensing can become aberrant and act as a precursor for many vascular pathological and physiological processes such as cancer metastasis, atherosclerosis, cell differentiation, migration, and morphogenesis. Also, intracellular calcium signalling plays an important role in endothelial cell motility and in maintaining vascular tone. Alteration in ECM composition has been linked to several pathologies, in fact, a transition to a fibronectin-rich matrix from a type …

Diffusion Biomarkers To Characterize Tissue Microstructure In Chronic Myocardial Infarction, Mohammad Tanjib Rahman

Electronic Theses and Dissertations, 2020-2023

Non-invasive imaging techniques to detect and characterize infarcted myocardium are critical for myocardial infarction (MI) prognosis and post-MI risk assessment. Many existing imaging techniques (such as T1-mapping) for MI detection require the use of contrast agents, which are not recommended for patients with renal failure. Cardiac diffusion tensor magnetic resonance imaging (cDTI), a non-contrast imaging technique, allows estimating the aggregate cardiomyocyte microstructure in healthy subjects and its remodeling as a result of cardiac diseases. Two main questions are investigated in this thesis: 1) how cDTI based biomarkers can characterize microstructural changes occurring post-MI; and 2) if cDTI based biomarkers can …

Optimization Of A Wing Supporting A Coaxial Rotor For Multiple Flight Conditions, Tadd Yeager

Electronic Theses and Dissertations, 2020-2023

Rotor-powered drones continue to grow in popularity in private and government sectors. The use of these drones in challenging environments and in high stakes applications calls for a certain level of robustness and redundancy. Often, these drones are equipped with sets of paired coaxial rotors, which not only improve the performance of the vehicle, but also ensure that a failure of one motor does not constitute the failure of the whole vehicle. Some applications such as extraterrestrial exploration, which use these coaxial rotors, can benefit from a wing shaped rotor arm to reduce drag and increase lift, extending mission lifetime. …

A Framework For Mitigating Obsolescence In Military Based Systems, Ryan Rust

Electronic Theses and Dissertations, 2020-2023

Obsolescence is an unavoidable reality in manufacturing systems and supply chain environments as systems are needed to be sustained for longer and longer periods of time. These extended life cycle products include airplanes, ships, industrial equipment, medical equipment, and military systems. The United States military has coined this issue as Diminishing Manufacturing Sources and Material Shortages (DMSMS). Research shows that the main areas of concern for obsolescence are cost optimization, obsolescence management, system life cycle, design/system refresh planning, architecture/open systems, and end-of-life (EOL) predictions. This effort suggests a need for a more effective management approach to tackling obsolescence with an …

Eeg-Based Signatures Of Isometric Arm Forces By Females At Different Levels Of Physical Exertion And Comfort, Mahjabeen Rahman

Electronic Theses and Dissertations, 2020-2023

In recent years, electroencephalography (EEG) has become a valuable technique for ergonomics studies of physical activities and other real-life tasks. Since the perception of force exertion is influenced by various psychophysical, cognitive, and social factors, different subjective measures have been traditionally used to measure the perception of physical exertion and related body discomfort. Along with the subjective measures, research showed that neural signals are also necessary objective measures to understanding human perception of physical tasks. However, EEG signatures of different physical exertion levels and perceived physical comfort have not been explored. The main objective of this study was to investigate …