Engineering Commons^™

Prediction And Validation Of Residual Stresses In Additively Manufactured Metal Parts, Jose Mayi Rivas

Electronic Theses and Dissertations, 2020-

Selective Laser Melted (SLM) Additively Manufactured (AM) metal parts are of special interest to many industries because their designs can be made arbitrarily complex while still maintaining bulk type mechanical properties. However, the large thermal gradients inherent to the SLM process generate residual stresses (RS) and distortions that are detrimental to the fit, functionality and integrity of parts. Predicting the state of stresses in as-built 3D printed parts is a difficult problem that currently has only been approached with the use of transient thermomechanical Finite Element Models (FEMs). The nonlinearities associated with AM processes are difficult to capture in these …

Lithium-Ion Battery Prognosis With Variational Hybrid Physics-Informed Neural Networks, Renato Giorgiani Do Nascimento

Electronic Theses and Dissertations, 2020-

Lithium-ion batteries are an increasingly popular source of power for many electric applications. Applications range from electric cars, driven by thousands of people every day, to existing and future air vehicles, such as unmanned aircraft vehicles (UAVs) and urban air mobility (UAM) drones. Therefore, robust modeling approaches are essential to ensure high reliability levels by monitoring battery state-of-charge (SOC) and forecasting the remaining useful life (RUL). Building principled-based models is challenging due to the complex electrochemistry that governs battery operation, which would entail computationally expensive models not suited for prognosis and health management applications. Alternatively, reduced-order models can be used …

An Investigation Of The Relationship Between Respiration And Seismocardiographic Signals Using Signal Processing, Machine Learning And Finite Element Analysis, Tanvir Hassan

Electronic Theses and Dissertations, 2020-

Cardiovascular disease (CVD) is one of the major causes of death worldwide. Disease management, as well as patient health, can be significantly improved by early detection of patient deterioration and proper intervention. Review of the patient's medical history and physical examination including stethoscope auscultation and electrocardiograms (ECG), echocardiography imaging, numerous blood testing, and computed tomography are common means of evaluating cardiac function. Seismocardiographic (SCG) signals are the vibrations of the chest wall due to the mechanical activity of the heart. These signals can provide useful information about heart function and could be used to diagnose cardiac problems. The variability in …

Vibrations Of Rotationally Periodic Structures: A Metric For Mistuning Characterization And Vibration Localization, Andres Rodriguez

Electronic Theses and Dissertations, 2020-

Blisk components are an integral part of jet engines and power generation systems. Composed of a single monolithic structure, integral blisks combine the blade-and-disk portion of primary components such as the fan, compressor stage, or turbine stage. This design modification increases the aerodynamic performance while decreasing the cost and eliminating time of assembly. However, these benefits come with the loss of blade-disk connection interfaces, which greatly reduces the structure's damping and its ability to attenuate unwanted structural vibrations. Blisk dynamics are impacted by mistuning, which is a disruption of the periodic symmetry of otherwise identical bladed sections. This disruption degrades …

Thermofluidic Characterization Of Carbon Dioxide Near Critical Conditions At Microscale, Anatoly Parahovnik

Electronic Theses and Dissertations, 2020-

This work revealed the thermo physical characteristics of near critical and supercritical carbon dioxide at the micro scale. The results include the extension of flow boiling heat transfer correlations, boiling inception, near critical bubble dynamics, thermalization mode shift, Joule Thomson effect and pressure drop evaluation. It was found that extremely low superheat temperatures are required for boiling inception near the critical conditions (i.e., T=31.4 °C, and P=7.37 MPa), and boiling heat transfer correlations were extended up to a reduced pressure of 0.99. The work also revealed a significant enhancement of the heat transfer coefficient as the critical conditions approached, which …

Autoignition Delay Time Measurements And Chemical Kinetic Modeling Of Hydrogen/Ammonia/Natural Gas Mixtures, Jessica Baker

Electronic Theses and Dissertations, 2020-

In recent years, hydrogen-carrying compounds have accrued interest as an alternative to traditional fossil fuels due to their function as zero-emission fuels. As such, there is interest in investigating hydrogen-carrying compounds to improve understanding of the fuels' characteristics for use in high pressure systems. In the current study, the oxidation of ammonia/natural gas/hydrogen mixtures was carried out to study CO formation profiles as well as the ignition delay times behind reflected shock waves in order to refine chemical kinetic models. Experiments were carried out in the University of Central Florida's shock tube facility by utilizing chemiluminescence to obtain OH* emission …

Heat Transfer Characterization Of Carbon Dioxide In Micro Impinging Jet(S) Near Critical Conditions, Stephen Adeoye

Electronic Theses and Dissertations, 2020-

The continuous growth and demand of increased operating performances of electronics has brought about an increase in the chip power density posing threat to the thermal management of these devices. Although numerous thermal solutions ranging from passive to active cooling together with a variety of working fluids have been adopted, however, the question whether these available cooling methods could meet up with the ever-growing need for increased operating performances is a concerning one. Jet impingement cooling has been effectively used in many industrial applications due to its high heat transfer capability. The limited study at the micro scale suggests that …

Data-Driven Modeling Of Mechanical Behaviors Of Additively Manufactured Materials, Ziyang Zhang

Electronic Theses and Dissertations, 2020-

Additive manufacturing (AM) is a revolutionary technology that greatly improves the flexibility of fabricating parts with complex structures and eliminates the cost of making molds. While AM techniques offer unique benefits over traditional manufacturing processes, it is challenging to predict the mechanical behaviors of additively manufactured parts based on design and process parameters. With recent advances in machine learning, data-driven methods have the potential to overcome such limitations. In this work, data-driven modeling frameworks were proposed to predict the tensile, flexural, and compressive behaviors of additively manufactured plastics and composites. Ensemble learning was used to predict the tensile strength of …

Decentralized Digital Fabrication Of Flexible Micro/Nano Devices Using A Laserjet Printer, Arshya Bamshad

Electronic Theses and Dissertations, 2020-

The fabrication of traditional micro/nano devices requires access to cleanrooms, complex and expensive tools, and highly-skilled labor. A facile and digital do-it-yourself (DIY) technique for the fabrication of low-cost devices on flexible substrates (paper, cloth, and plastic films) is presented in this work. A set of office-grade equipment (i.e., laserjet printer, thermal laminator, computer-aided paper cutter), and commercially available supplies (i.e., baking wax paper, furniture restoration metal-leaf) are utilized. The presented technology enables community-embedded production by removing a high technological barrier. The validity of the proposed technology was proved by designing three levels of experiments, i.e., patterns, devices, and systems. …

A Flexible 3d Architecture For Cooling Future Generation Devices, Khan Mohammad Rabbi

Electronic Theses and Dissertations, 2020-

Systems that consume and convert energy produce thermal energy as a byproduct. This generation of thermal energy, if not dissipated properly, contributes to the significant temperature rise of the overall system. This temperature rise can lead to reduced efficiency and system-level failure. Future technologies will continue to face such thermal challenges. In fact, next-gen devices will demand flexible thermal management architectures for high-performance operation. To tackle these challenges, innovative liquid cooling technologies and high-speed thermal diagnostic systems must be developed simultaneously. Active and passive pulsation-liquid-cooling techniques are currently an attractive thermal management solution. In an active cooling mode, the influence …

An Investigative Design Of Gas Jet Nozzles And Their Flow Field Effect On Spatial Distribution, Adam Phengsomphone

Honors Undergraduate Theses

Within this study, the presented material has the objective of providing insight and design characteristics for gas jet nozzles that experimentalists and researchers should consider when utilizing this experimental method. Firstly, this study introduces the developing history and necessity for gas jet experiments and its well-known drawbacks, eventually leading to recent studies and founded knowledge regarding the nozzle geometry dependence on the flow field. The simulation methodology of this study will be presented where the discretization of the computational domain, selection of the flow physics model, and overall design of the nozzle geometry is explained and justified. The flow field …

An Introduction To The Comparison Of Seismocardiography And Phonocardiography, Anna C. Voyatzoglou

Honors Undergraduate Theses

The intent of this thesis is to lay groundwork for examining the relationship between seismocardiography (SCG) and phonocardiography (PCG). Both are methods of measuring and describing heart mechanical function. SCG is described as chest vibrations while the heart beats, and PCG is described as acoustic chest surface signal believed to represent the heart valves opening or closing. SCG and PCG have both been used separately in clinical and research settings, but there is currently no clear comparison between the two. Therefore, there has been no way at the present to understand how one signal might inform the other. This study …

Probing The Effect Of Hyperglycemia On Endothelial Force Generation And Transmission, Jovani J. Gutierrez

Honors Undergraduate Theses

This thesis intends to utilize biomechanics to study the endothelial biomechanical response in a static hyperglycemic microenvironment. Hyperglycemia is a diabetic condition with abnormally high levels of glucose in the bloodstream. The effects of hyperglycemia over time lead to vascular complications resulting in patients being more prone to cardiovascular diseases. Current studies have focused on the molecular mechanisms affected by hyperglycemia; however, the mechanical mechanisms by which hyperglycemia causes vascular structural and functional changes are understudied. Therefore, to study the effects of hyperglycemia in the endothelium, Human Umbilical Vein Endothelial Cells (HUVEC) were cultured under three glucose conditions: normal glucose …

Design And Development Of Medical Devices For Multifaceted Applications, Madisyn Messmore

Honors Undergraduate Theses

The fields of biotechnology and biomedical sciences are rapidly evolving and involve the constant growth of knowledge. As a consequence, engineering design has to also remain at the cutting edge in order to not inhibit the growth of these fields. This study focuses on engineering design and analysis as it pertains to the field of biotechnology, at every step of the engineering process. More specifically, how the engineering design and analysis approach can assist in solving medical problems relating to bone diseases and biomaterials. The first part of the study focuses on a project to design and manufacture a novel …

Quantitative Metallurgy Of Anisotropic Nickel-Base Superalloys Under Tensile And Fatigue Loading, Dominic Devito

Electronic Theses and Dissertations, 2020-

Nickel-base superalloys are ideal materials for application in high temperature and high stress environments. Their resistance to both heat and corrosion makes these metals well-suited for use as components in engines and turbines. There has been much interest in characterizing the mechanical properties of Ni-base superalloys under severe conditions. Either large monotonic loads or cyclic loads are the most investigated. Also, research efforts tend to focus on the influence of microstructural features of fatigue life, and they accomplish this through qualitative observation. Presented here is both quantitative and qualitative analysis done on Ni-base superalloy specimens that have been subjected to …

Generative Adversarial Networks For Extrapolation Of Corrosion In Automobile Images, Andre Von Zuben

Electronic Theses and Dissertations, 2020-

Deep learning has shown success in several applications involving pattern recognition, expert systems, and scientific discovery. However, existing methods struggle with industrial applications, which are often challenged by non-ideal datasets. In many cases, the datasets are small, poorly labeled, noisy, or have unbalanced class distribution or any combination of such problems. In this Master's research, we propose a generative adversarial network (GAN) strategy that is able to circumvent limitations imposed by tiny datasets. As a case study, we use the extrapolation of corrosion in automobiles and feed our deep learning framework with only a few dozen images instead of the …

Crystal Viscoplastic Modeling Of Single Crystal And Directionally Solidified Nickel-Base Superalloys, Navindra Wijeyeratne

Electronic Theses and Dissertations, 2020-

Nickel-base superalloys (NBSAs) are widely used in engineering applications for many turbomachinery component designs. Superior material properties at high temperatures such as high tensile strength, superior fatigue strength, excellent resistance to thermal shocks, and strong corrosion resistance are primarily responsible for their extensive application. This proposal focuses on modeling generic single crystal (SX) and directionally solidified (DS) Ni-base superalloy. Compared to polycrystal superalloys, SX superalloys exhibit superior thermal fatigue and creep resistance which is attributed to the absence of grain boundaries in the SX crystalline structure. Directional solidification procedures enable the solidification structure of the materials to be comprised of …

Experimental And Computational Heat Transfer Study Of Sco2 Single Jet Impingement, John Richardson

Electronic Theses and Dissertations, 2020-

The present study experimentally investigates the heat transfer capability of supercritical carbon dioxide (sCO2) single-jet impingement. The evaluated jet Reynolds number range is between 80,000 and 1,000,000, with a non-dimensional jet-to-target surface spacing of 2.8. CO2-impinging jet stagnation conditions were maintained at approximately 20 MPa and a temperature of 673 K for most experiments. The goal is to understand how changes in the aforementioned parameters influence heat transfer between the working fluid and the heated surface. Additionally, due to the elevated Reynolds numbers and difference in thermodynamic properties between air and CO2, air-derived impingement correlations may not be appropriate for …

Mean Pressure Gradient Effects On Flame-Flow Dynamics In A Cavity Combustor, David M. Smerina

Honors Undergraduate Theses

Pressure gradient confinement effects are experimentally investigated within a cavity combustor to analyze the flame interactions of premixed, cavity stabilized, flames in a high-speed combustor. Pressure gradient confinement effects are generated in a dual mode ramjet-scramjet (DMSR) by varying the wall geometry to form converging, diverging, and nominal configurations. The velocity field and flame position are captured temporally using simultaneous high-speed particle image velocimetry (PIV) and CH chemiluminescence. The evolution of the flow field and flame structure are analyzed, and the high temporal resolution of these measurements allows for the characterization of turbulence-flame interactions. Consideration of the combustion mode and …

Anomaly Detection And Failure Prediction In Gas Turbines, Vipul Goyal

Electronic Theses and Dissertations, 2020-

This study is based on time-series data taken from the combined cycle heavy-duty utility gas turbines. For analysis, first, a multi-stage vector autoregressive model is constructed for the nominal operation of powerplant assuming sparsity in the association among variables, and this model is used as a basis for anomaly detection and prediction. This prediction is compared with the time-series data of the powerplant test data containing anomalies. Granger causality networks, which are based on the associations between the time series streams, can be learned as an important implication from the vector autoregressive modelling. This method suffers from the disadvantage that …

Topology Optimization Of Internal Cooling Channels In Turbulent Flows, Shinjan Ghosh

Electronic Theses and Dissertations, 2020-

Topology optimization, introduced by Bendsoe and Sigmund in 1988 has been a topic of research in the structural mechanics field for several decades. This technique is commonly used to optimize system performance of structural components with minimum material usage by varying the distribution of materials in a given domain. Fluid dynamic topology optimization, a relatively new research topic uses a method of adding or subtracting materials to a given flow domain to obtain an optimal flow-path for a given objective function. While the structural TO creates a solid structure by introducing holes into the domain, fluid TO introduces solid into …

Synthesis And Assessment Of Sustainable Fuels For Transportation And Space Exploration, Katerina Chagoya

Electronic Theses and Dissertations, 2020-

As global energy sources transition towards renewable energy, the demand for sustainable fuels has never been greater. The sheer scale of this transition will require numerous solutions to accommodate for the diverse and complex situations worldwide. This dissertation will discuss 3 studies: the utilization of CO2 waste gas to produce fuels sustainably, characterizing biofuels for efficient use in automobiles, and developing a solid, emissonless fuel intended for spaceflight but also applicable on Earth. The hydrogenation of CO2 into value-added molecules could reduce greenhouse gas emissions if waste stream CO2 were captured for conversion. We found that atomic vacancies induced in …

Tailoring Of The Left Ventricular Assist Device Cannula Implantation Using Coupled Multi-Scale Multi-Objective Patient Specific Optimization., Abubakar Dankano

Electronic Theses and Dissertations, 2020-

Despite advancements in device design and anti-coagulation treatments, there are numerous adverse events that may occur following implantation of LVADs. The most devastating involves the embolization of thrombus into the brain causing a stroke, with incidence of up to 14-47% over a 6–12-month period. This study aims to elucidate ways to reduce this risk by surgical maneuvers guided by a multi-scale computational fluid dynamics analysis wrapped around a multi-objective shape optimization scheme which optimizes the anastomosis location of the VAD outflow graft (OG) along the ascending aorta to minimize the incidence of thrombi reaching the cerebral vessels and reduce particle …

A Framework For The Design And Characterization Of Advanced Gaskets, Sannmit Shinde

Electronic Theses and Dissertations, 2020-

Most industrial manufacturing or processing plants use bolted connections between pipes that transfer media from one location to another. Gaskets are often used to seal these systems as they offer elevated levels of leak mitigation; however, despite their nearly universal usage, the current understanding of gasket mechanics at the meso-scale is still limited. Contemporary gaskets feature viscoelastic materials, fillers, textures, and are fabricated at various thicknesses. They are used in a wide range of thermal, mechanical, chemical, and temporal conditions. The current work characterizes polytetrafluoroethylene (PTFE) gaskets made with several different filler materials and having vastly different geometries. The chemically …

Connected Water Heater Load Shifting And Energy Efficiency Evaluation For The Southeast: Winter Laboratory Assessment, Final Report, Florida Solar Energy Center, Karen Fenaughty

FSEC Energy Research Center®

The University of Central Florida's FSEC Energy Research Center (FSEC) and Pacific Northwest National Laboratory (PNNL) are conducting laboratory electrical load shifting experiments using the CTA-2045-A standard to demonstrate the viability of grid-connected heat pump water heaters (HPWH), compared to electric resistance water heaters (ERWH), in providing load shifting in the Southeastern United States (U.S.). The investigation applied different CTA-2045 shed and critical peak (CP) control command designs under two different water draw profiles. The highly-controlled laboratory experiments were conducted on four HPWHs and one ERWH from December 2020 through February 2021.

The research aimed to evaluate the load shifting …

Comparison Of The Residential Provisions Of The 7th Edition (2020) Florida Building Code, Energy Conservation With The 2021 Iecc, Florida Solar Energy Center, Jeffrey Sonne

FSEC Energy Research Center®

This report provides a comparison between the 7th Edition (2020) Florida Building Code, Energy Conservation (FBC-EC) and 2021 International Energy Conservation Code (IECC), based on approved 2018 to 2021 IECC changes included in the International Code Council's Complete Revision History to the 2021 I-Codes document. The first part of this study involved developing code change listings based on the Revision History document that identify changes that have potential energy and cost impacts. This second part of the study provides a stringency evaluation and cost-benefit analysis for those changes that impact energy use, to provide guidance for the upcoming 2020 FBC-EC …

Comparison Of The Commercial Provisions Of The 2020 Florida Building Code, Energy Conservation, 7th Edition With 2021 Iecc & Ashrae 90.1-2019, Florida Solar Energy Center, Bereket Nigusse

FSEC Energy Research Center®

This report provides comparison of the commercial provisions of the 7th Edition (2020) Florida Building Code, Energy Conservation (FBC-EC) with the 2021 International Energy Conservation Code (IECC) and ASHREA 90.1-2019. The first part developed code changes listing identifying energy and construction cost impacts. The second part analyzed energy and energy cost savings potential of the 2021 IECC and the 2019 ASHRAE 90.1 compared to the 2020 FBC-EC using prototype buildings energy model and simulation. And performed cost-benefit analysis of code changes with energy impact and provided recommendation for consideration by Florida Building Commission for addition to the 8th Edition (2023) …

Mitigation Of Airborne Contaminant Spread Through Simple Interventions In An Occupied Single-Family Home, Florida Solar Energy Center, Nazim Muradov

FSEC Energy Research Center®

Historically, reducing aerosol-based transmission of respired viruses in indoor environments has been of importance for controlling influenza viruses and common-cold rhinoviruses. The present public health emergency associated with SARS-CoV-2 makes this topic critically important. Yet to be tested is the potential effectiveness of simple interventions that create an isolation zone (IZ) for a suspected/confirmed sick or sensitive person requiring quarantine. The intent in existing homes is to find a practical means to mitigate exposure to airborne contaminants. In creating an IZ in an occupied single-family home in the study, four simple strategies were tested. The test configurations were: (1) IZ …

Lab Home Testing Of Residential Isolation Space Control To Minimize Infectious Disease Transmission In Existing Single-Family Homes, Florida Solar Energy Center, Tanvir Khan

FSEC Energy Research Center®

Existing evidence strongly suggests that viral infectious diseases can be transmitted via an airborne route across distances in indoor environments. Accordingly, the risk of airborne transmission within homes should be managed. The public health emergency associated with SARS-CoV-2 makes controlling airborne transmission of respired viruses in indoor environments critical, especially in poorly ventilated indoor environments. The effectiveness of engineering interventions requiring minor efforts that create a negative-pressure isolation zone (IZ) for a contagious person has yet to be tested for existing residential homes.

To mitigate the risk of airborne virus transmission and maximize health protection for the population in existing …

Lab Home Testing Of Residential Isolation Space Control To Minimize Infectious Disease Transmission In Existing Single-Family Homes -- Fact Sheet, Florida Solar Energy Center, Tanvir Khan

FSEC Energy Research Center®

The FSEC Energy Research Center at the University of Central Florida performed research to test the effectiveness of interventions to isolate an ill person recovering from a contagious disease in a single-family home from the rest of the occupants in the home. Focus was placed on interventions requiring minor cost and effort on the part of the occupants.

DOE/GO-102021-5537, https://www.nrel.gov/docs/fy21osti/79519.pdf