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University of Central Florida

2021

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Articles 151 - 178 of 178

Full-Text Articles in Engineering

Hotspot Cooling Performance For Confined Jet Impingement Cooling, Tanvir Ahmed Chowdhury Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Neural Signatures Of Human Perception Of Effort And Comfort In Isometric Arm Force Exertions By Males, Raul Fernandez Sumano Jan 2021

Neural Signatures Of Human Perception Of Effort And Comfort In Isometric Arm Force Exertions By Males, Raul Fernandez Sumano

Electronic Theses and Dissertations, 2020-

Understanding the brain's electrical activity provides objective evidence of different psychophysical phenomena related to manual handling tasks. The primary objective of this research was to assess the neural signatures of human physical efforts and perceived comfort in isometric arm exertions. Two experiments were conducted with male participants (n=20) who applied isometric forces at 1) different levels of exertion and 2) different levels of physical comfort. EEG signals, the rate of perceived exertion (RPE), and the rate of perceived physical comfort (RPC) have been recorded. The results showed statistically significant differences in EEG's power spectral density (PSD) at different brain regions …


Evaluating Source Water Quality, Pretreatment, And Particulate Mass Transport In A Nanofiltration Membrane Process, Courtney Powell Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Periodicity Estimation Using Representations In Nested Periodic Dictionaries With Applications In Neural Engineering, Pouria Saidi Jan 2021

Periodicity Estimation Using Representations In Nested Periodic Dictionaries With Applications In Neural Engineering, Pouria Saidi

Electronic Theses and Dissertations, 2020-

In this dissertation, we investigate periodicity estimation with nested periodic dictionaries (NPDs), a newly introduced family of matrices that can capture periodicity in the data. We address two main problems. First, we study the detection of periodic signals using their representations in NPDs. To this end, the detection problem is posed as a composite hypothesis testing problem, where the signals are assumed to admit sparse representations in a Ramanujan Periodicity Transform (RPT) dictionary as an instance of NPDs. For the binary case, we develop a generalized likelihood ratio detector and obtain exact distributions of the test statistics in terms of …


Diffusion Biomarkers To Characterize Tissue Microstructure In Chronic Myocardial Infarction, Mohammad Tanjib Rahman Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Using A Lubricin Reporter Cell To Test Current Vs. Optimized Media Compositions, Sean M. Kennedy Jan 2021

Using A Lubricin Reporter Cell To Test Current Vs. Optimized Media Compositions, Sean M. Kennedy

Honors Undergraduate Theses

Osteoarthritis is a joint disease characterized by the breakdown of articular cartilage. The field of tissue engineering is interested in developing methods to produce biological alternatives to current orthopedic procedures. Lubricin is a molecule which is important in the proper lubrication of articular cartilage. It is a challenge in the field of tissue engineering to produce cartilage with sufficient lubricin expression. Developing a reporter cell for lubricin allowed for a more efficient investigation of the conditions wh­­­ich may influence its expression. By comparing "optimized" and traditional media solutions, it was determined that the use of a previously reported type II …


On The Strategic Relationship Between Leadership And Innovation In Us Firms, Shabeer Kirmani Jan 2021

On The Strategic Relationship Between Leadership And Innovation In Us Firms, Shabeer Kirmani

Electronic Theses and Dissertations, 2020-

Leadership is one of the most important factors in organizational success. Innovation is another of most important factors in organizational success. Leaders play a pivotal role in the innovation capabilities of organizations. One of the most important areas in Leadership Studies (LS) is the association between leadership style and the firm's innovation performance, but a lack of understanding and consensus still remains as a major issue. This research aims to address the research gap by reviewing the empirical literature and determining how the ambidextrous leadership (transactional and transformational) styles in top level U.S. management (CEOs) are related with firm ambidextrous …


Applying Machine Learning Techniques To Improve Safety And Mobility Of Urban Transportation Systems Using Infrastructure- And Vehicle-Based Sensors, Zubayer Islam Jan 2021

Applying Machine Learning Techniques To Improve Safety And Mobility Of Urban Transportation Systems Using Infrastructure- And Vehicle-Based Sensors, Zubayer Islam

Electronic Theses and Dissertations, 2020-

The importance of sensing technologies in the field of transportation is ever increasing. Rapid improvements of cloud computing, Internet of Vehicles (IoV), and intelligent transport system (ITS) enables fast acquisition of sensor data with immediate processing. Machine learning algorithms provide a way to classify or predict outcomes in a selective and timely fashion. High accuracy and increased volatility are the main features of various learning algorithms. In this dissertation, we aim to use infrastructure- and vehicle-based sensors to improve safety and mobility of urban transportation systems. Smartphone sensors were used in the first study to estimate vehicle trajectory using lane …


Corticomuscular Adaptation To Mechanical Perturbations In A Seated Locomotor Task, Seyed Yahya Shirazi Jan 2021

Corticomuscular Adaptation To Mechanical Perturbations In A Seated Locomotor Task, Seyed Yahya Shirazi

Electronic Theses and Dissertations, 2020-

Cortical control during walking is most pronounced when the person is perturbed. Although seated locomotor tasks such as cycling or recumbent stepping improve walking performance, the electrocortical correlates of perturbed seated tasks have not been studied in detail. The primary purpose of this research was to quantify cortical and muscular responses to mechanical perturbations during recumbent stepping. We also aimed to quantify possible differences between young and older adults' responses to perturbed stepping. A secondary aim of this research was to determine the accuracy of electroencephalography (EEG) source imaging to interpret the electrocortical findings adequately. We hypothesized that both young …


Low-Profile Wireless Passive Temperature Sensors, Ectis Velazquez Jan 2021

Low-Profile Wireless Passive Temperature Sensors, Ectis Velazquez

Electronic Theses and Dissertations, 2020-

This thesis explores design challenges and promising solutions for temperature sensors for high temperature environments such as combustion turbines. To survive this high temperature environment of over 1000 °C the sensors are required to be robust in their electrical and mechanical properties. Wire connections for these high temperature environments are a complex problem due to the physical limitations of most materials at those high temperatures. In this thesis, robust ceramic sensors based on microwave resonators are demonstrated for high temperature environments, with some studies into optimizing the techniques used to measure them, as well as the distance at which their …


Robust Acceleration Of Data-Centric Applications Using Resistive Computing Systems, Baogang Zhang Jan 2021

Robust Acceleration Of Data-Centric Applications Using Resistive Computing Systems, Baogang Zhang

Electronic Theses and Dissertations, 2020-

With the accessible data reaching zettabyte level, CMOS technology is reaching its limit for the data hungry applications. Moore's law has been reaching its depletion in recent studies. On the other hand, von Neumann architecture is approaching the bottleneck due to the data movement between the computing and memory units. With data movement and power budgets becoming the limiting factors of today's computing systems, in-memory computing using emerging non-volatile resistive devices has attracted an increasing amount of attention. A non-volatile resistive device may be realized using memristor, resistive random access memory (ReRAM), phase change memory (PCM), or spin-transfer torque magnetic …


Computational Studies For Extending Understanding Of Complex Droplet Breakup Mechanisms, Caroline Anderson Jan 2021

Computational Studies For Extending Understanding Of Complex Droplet Breakup Mechanisms, Caroline Anderson

Electronic Theses and Dissertations, 2020-

Conventional methods of classifying droplet breakup are evaluated in the context of unique variation in environmental and droplet fluid conditions. Most characterization is developed for subsonic speeds and Newtonian fluids, so this study extends understanding on how these forms change to a span of applications outside these conditions. Presented examples include the impact effects on hypersonic vehicles travelling through precipitation, where even smallest of rain drops at such speeds can cause damage. Before the droplet even reaches the vehicle, it interacts with the detached bow shock that leads it. Another example of exceptional recent concern is risk of viral transmission …


The Effect Of Annealing Temperatures And Inert/Reactive Gasses On Optical Properties Of Cu2o And Cuo Thin Films, Radu Bunea Jan 2021

The Effect Of Annealing Temperatures And Inert/Reactive Gasses On Optical Properties Of Cu2o And Cuo Thin Films, Radu Bunea

Electronic Theses and Dissertations, 2020-

The Cu2O and CuO thin films were synthesized by using RF sputtering technique. Comparisons were made with films created by deposition at room temperature followed by thermal annealing between 1000C and 4000C and using different gases, oxygen (O2) (oxidizing and reactive gas) and nitrogen (N2) (inert gas), besides air. The thickness of the thin films were kept constant, around 2000 Å (Angstrom). In addition, the RF power and pressure deposition were kept constant, as well. The thin films were evaluated for a range of wavelengths between 200 nm and 400 nm (Ultra Violet spectrum), …


Harvesting Heat From Safer, Energy-Dense Slow Pyrolant Mixtures For Future Space Missions, Katerina Chagoya Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Impact Of Crowder Size On Actin Filament Assembly Kinetics, Bryan Demosthene Jan 2021

Impact Of Crowder Size On Actin Filament Assembly Kinetics, Bryan Demosthene

Electronic Theses and Dissertations, 2020-

Actin is an abundant and essential cytoskeletal protein that plays a central role in eukaryotic cell structure and motility. The intracellular environment where actin assembly occurs is crowded with various organelles, proteins, and macromolecules that limit the accessible volume for biomolecular reactions. Macromolecular crowding induces excluded volume effects influencing the activity of biological molecules as well as the shape and conformation of proteins. Crowding agents, such as polysaccharides or inert polymeric molecules, are used to mimic the conditions present in intracellular spaces and provide a better understanding of interactions inside the cell. Macromolecular crowding has been shown to affect actin …


Atomically Thin Platinum-Based Dichalcogenide Materials For Multifunctional Photo-Sensitive Applications, Mashiyat Sumaiya Shawkat Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Laser-Microdrop Interactions In Nanoparticle Deposition On Solid Substrates, Tianyi Li Jan 2021

Laser-Microdrop Interactions In Nanoparticle Deposition On Solid Substrates, Tianyi Li

Electronic Theses and Dissertations, 2020-

Nanoparticle suspensions are utilized for depositing thin films on solid substrates by a process called nano electrospray laser deposition. In this research, three deposition methods, contact liquid line laser printing, nano-electrospray laser sintering and evaporative optical Marangoni convection are investigated experimentally and analytically. Thin silver lines are printed on indium tin oxide-coated silicon substrates by dispensing silver nanoparticle suspension with a micropipe of inner diameter 51µm and subsequently sintering the nanoparticles with a CO2 laser beam of Bessel intensity profile. The deposited silver lines of 65µm width and 1µm height have good resistivity which can be used to manufacture silver …


Characterization Of Hydrogenated Boron Carbide And Boron Carbon Nitride Thin Films And Applications, Shraddha Dhanraj Nehate Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Improving Performance And Flexibility Of Fabric-Attached Memory Systems, Vamsee Reddy Kommareddy Jan 2021

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

Electronic Theses and Dissertations, 2020-

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 …


Safety And Operations Of Urban Arterials Incorporating The Context Classification System, Nada Mahmoud Jan 2021

Safety And Operations Of Urban Arterials Incorporating The Context Classification System, Nada Mahmoud

Electronic Theses and Dissertations, 2020-

Urban arterials connect multiple areas in the city and encourage non-motorist activities. Hence, the safety and operations on urban arterials is vital as they improve the mobility of daily commuters and road users. This research aims to facilitate traffic operations on urban arterials by proposing multiple mythological approaches to estimate and predict turning movement counts at signalized intersections using traffic data from adjacent intersections. Further, it aims to improve the safety by developing crash prediction models, identifying the hotspots for multiple crash types, and indicating the factors contributing to operating speed as well as non-motorist crashes. The analyses included tuning, …


Mechanically Reconfigurable Materials And Devices Based On Two-Dimensional Transition Metal Dichalcogenide Layers, Emmanuel Okogbue Jan 2021

Mechanically Reconfigurable Materials And Devices Based On Two-Dimensional Transition Metal Dichalcogenide Layers, Emmanuel Okogbue

Electronic Theses and Dissertations, 2020-

The recent advances in electronic technologies are geared towards a combination of continued miniaturization in device components and their integration onto unconventional platforms. These efforts are aimed towards achieving electronic devices with various form factors and novel functionalities which are unattainable from traditional devices. Among these envisioned 'futuristic' technologies, electronic devices which are mechanically reconfigurable and operable under harsh operational conditions in the form of stretching, twisting and folding offer tremendous amount of unparalleled opportunities. This dissertation studies two-dimensional (2D) transition metal dichalcogenide (TMDs), a distinct class of materials with peculiar optical, electrical and mechanical properties for mechanically reconfigurable electronics. …


Mechanical Behavior Of Bioceramic Materials: Case Study Of The Skeleton Of The Staghorn Coral, Acropora Cervicornis And The Tibia Of The Laboratory Mouse, Mus Musculus, Mahmoud Omer Jan 2021

Mechanical Behavior Of Bioceramic Materials: Case Study Of The Skeleton Of The Staghorn Coral, Acropora Cervicornis And The Tibia Of The Laboratory Mouse, Mus Musculus, Mahmoud Omer

Electronic Theses and Dissertations, 2020-

I studied two types of bioceramics: (A) the aragonite CaCO3 skeleton of the staghorn coral, Acropora cervicornis and (B) the hydroxyapatite Ca10(PO4)6(OH)2 bones of the laboratory mouse, Mus musculus. The research aimed to analyze coral deformation behavior and study dietary and estrogen depletions effects on bone strength. I compared the mechanical and structural properties of staghorn coral skeletons cleaned by chemical bleaching and biological processes. Optical microscopy and computed tomography (CT) revealed a sophisticated microstructure of non-homogenously distributed pores. Staghorn coral skeletons showed ''gracious" fracture, where the unique pore arrangements resisted catastrophic crack growth and prevented instantanous failure. Elastic moduli …


Material Properties Of 17-4ph Stainless Steel Fabricated With Cooling Holes By Atomic Diffusion Additive Manufacturing (Adam), Nandhini Raju Jan 2021

Material Properties Of 17-4ph Stainless Steel Fabricated With Cooling Holes By Atomic Diffusion Additive Manufacturing (Adam), Nandhini Raju

Electronic Theses and Dissertations, 2020-

The objective of this study is to investigate the material properties of 17-4PH stainless steel printed with cooling holes in different build orientations by the Atomic Diffusion Additive manufacturing technique. Samples with film cooling holes printed in different build orientations, with impingement inserts, impingement cavities were manufactured in a Markforged Metal-X machine. The presence of the holes in these samples helps to understand the printability and accuracy of internal cooling holes, as manufactured by the Metal-X machine. Manufactured samples were first washed to remove the plastic binder. These pre-sintered samples were tested, for density, microstructure analysis, roughness, Energy Dispersive X-ray …


The Effect Of Polyelectrolyte Modification Of Ultrafiltration Membranes On Fouling Resistance And Rejection Of Contaminants Of Emerging Concern, Kunal Olimattel Jan 2021

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-

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 …


Real-Time Traffic Safety Evaluation In The Context Of Connected Vehicles And Mobile Sensing, Pei Li Jan 2021

Real-Time Traffic Safety Evaluation In The Context Of Connected Vehicles And Mobile Sensing, Pei Li

Electronic Theses and Dissertations, 2020-

Recently, with the development of connected vehicles and mobile sensing technologies, vehicle-based data become much easier to obtain. However, only few studies have investigated the application of this kind of novel data to real-time traffic safety evaluation. This dissertation aims to conduct a series of real-time traffic safety studies by integrating all kinds of available vehicle-based data sources. First, this dissertation developed a deep learning model for identifying vehicle maneuvers using data from smartphone sensors (i.e., accelerometer and gyroscope). The proposed model was robust and suitable for real-time application as it required less processing of smartphone sensor data compared with …


Bicycle Wheel Aerodynamics Predictions Using Cfd: Efficiency Using Blade Element Method, Drew Vigne Jan 2021

Bicycle Wheel Aerodynamics Predictions Using Cfd: Efficiency Using Blade Element Method, Drew Vigne

Honors Undergraduate Theses

The cycling industry has long relied on expensive wind tunnel testing when designing aerodynamic products, particularly in the context of wheels which account for 10 to 15 percent of a cyclist's total aerodynamic drag. With the recent advent of Computational Fluid Dynamics (CFD), the industry now has an economical tool to supplement the wheel design process; however, the complex nature of rotating spoked wheels requires high resolution meshes to model at acceptable fidelity. This research investigates an alternative CFD method that lowers the computational cost of modeling aerodynamic bicycle wheels by modeling spokes using Blade Element Method (BEM). Two CFD …


A Finite Difference Model For Induced Hypothermia During Shock, Dylan S. Lyon Jan 2021

A Finite Difference Model For Induced Hypothermia During Shock, Dylan S. Lyon

Honors Undergraduate Theses

The modified Fiala model from Westin was implemented with conditions for circulatory shock and hypothermia. The purpose is to model Emergency Preservation and Resuscitation (EPR), a procedure for inducing hypothermia in patients. Cold tissue temperatures reduce metabolism exponentially, greatly extending the window of anaerobic metabolic activity before permanent deoxygenation damage. EPR in patients undergoing hypovolemic shock can preserve the patient until primary surgical care and blood transfusions are attainable., thereby increasing survival rates. The main applications of EPR are military in-situ stabilization for transit to clinical care and extending the survivability of patients requiring prolonged surgery before blood transfusion. The …


Experimental Study Of A Liquid Fuel Bluff Body Flame At Elevated Pressures, Karam Paul Jan 2021

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 …