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University of Central Florida

Theses/Dissertations

2022

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Full-Text Articles in Engineering

Polyelectrolyte Functionalized Forward Osmosis For Water Reclamation From Synthetic Spacecraft Wastewater, Alina Ripp Dec 2022

Polyelectrolyte Functionalized Forward Osmosis For Water Reclamation From Synthetic Spacecraft Wastewater, Alina Ripp

Electronic Theses and Dissertations, 2020-

This study investigated the application of a polyelectrolyte (PE)-assisted metallic iron nanoparticle-integrated forward osmosis (FO) membrane to treat synthetic spacecraft wastewater comprising urea, ammonium carbonate, and linear alkylbenzene sulfonate (LAS). The draw solution (MgSO4) diluted via the FO operation was further treated using a nanofiltration (NF) membrane aimed at producing potable quality water by the FO-NF hybrid process. A cellulose triacetate FO membrane was functionalized by layer-by-layer deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) followed by incorporating zero valent iron nanoparticles (ZVINP) within the "bilayers". It required 14 bilayers to ensure a uniform coating as demonstrated via scanning …


High Performance And Low Cost Passivating, Carrier-Selective Contacts For Silicon Photovoltaics, Jannatul Ferdous Mousumi Dec 2022

High Performance And Low Cost Passivating, Carrier-Selective Contacts For Silicon Photovoltaics, Jannatul Ferdous Mousumi

Electronic Theses and Dissertations, 2020-

The world is now focusing on expanding renewable energy sources to reduce the carbon footprint and mitigate climate change. Solar energy is one of the most environment-friendly and fastest-growing renewable energy sources in the present world. While crystalline silicon (c-Si) based devices dominate the global photovoltaics (PV) market with a current share of 95%, it is still challenging to achieve the theoretical efficiency limit of 29.4% with this technology due to a few performance limiting factors. Contact recombination losses are dominant among them which result from the recombination of photo-generated charge carriers due to the presence of defects at the …


Adaptive Analytic Continuation For The State Transition Tensors Of The Two-Body Problem, Tahsinul Haque Tasif Dec 2022

Adaptive Analytic Continuation For The State Transition Tensors Of The Two-Body Problem, Tahsinul Haque Tasif

Electronic Theses and Dissertations, 2020-

In the past few decades, Kessler syndrome (named after Donald J. Kessler) has become a point of concern in the field of Space Situational Awareness and the future of space missions. It refers to a scenario, where space debris in Earth's orbits collides and creates an exponential increase in space debris numbers leading to more collisions and more debris. In order to handle the resulting challenges like conjunction analysis, tracking, and probability of collisions, the State Transition Matrix (STM) and Tensors (STTs) of the orbit problem play a significant role. In addition, STM and STTs are ubiquitous in spaceflight dynamics, …


Distributed Detection In Energy Harvesting Wireless Sensor Networks, Ghazaleh Ardeshiri Dec 2022

Distributed Detection In Energy Harvesting Wireless Sensor Networks, Ghazaleh Ardeshiri

Electronic Theses and Dissertations, 2020-

A conventional wireless sensor networks (WSN), consisting of sensors powered by nonrechargeable batteries, has a strictly limited lifetime. Energy harvesting (EH) from the environment is a promising solution to address the energy constraint problem in conventional WSNs, and to render these networks to self-sustainable networks with perpetual lifetimes. In EH-powered WSNs, where sensors are capable of harvesting and storing energy, power control is necessary to balance the rates of energy harvesting and energy consumption for data transmission. In addition, wireless communication channels change randomly in time due to fading. These together prompt the need for developing new power control strategies …


Data-Driven Power System Stability Analysis And Control, Jian Xie Dec 2022

Data-Driven Power System Stability Analysis And Control, Jian Xie

Electronic Theses and Dissertations, 2020-

In recent years, with the expansion of power system size, the increase of interconnection and the use of large-scale renewable energy, power system stability and safe operations have become more prominent, causing challenges to the normal operation of power grid. Traditional analysis rely on detailed models of the system. But for real power systems, the operating state of the system is variable, and the model-based analysis methods may not accurately reflect the real operating state of the system. Therefore, this dissertation is focused on data-driven stability analysis and control. First, a method for locating the oscillation source of multi-machine systems …


Processing And Characterization Of Ultra High Temperature And High Conductive Composites, Haonan Song Dec 2022

Processing And Characterization Of Ultra High Temperature And High Conductive Composites, Haonan Song

Electronic Theses and Dissertations, 2020-

There are significant challenges for materials in extreme environments for a variety of applications such as aircraft engines, gas turbines, nuclear reactors, re-entry vehicles, and hypersonic structures. Ceramic matrix composites (CMCs) could be ideal candidates to meet these stringent requirements for materials due to their high melting temperatures, high oxidation, corrosion and ablation resistance, low creep, and thermal cycling behavior in such extreme environments. Particularly, continuous fibers can bridge cracks in CMCs and therefore improve the strength and fracture toughness of composites. Metal matrix ceramics are important materials in various industries, such as aerospace and automobile. MMCs have excellent mechanical …


High Voltage Aqueous Electrolyte Based Structural Supercapacitors For Electric Vehicles, Deepak Pandey Dec 2022

High Voltage Aqueous Electrolyte Based Structural Supercapacitors For Electric Vehicles, Deepak Pandey

Electronic Theses and Dissertations, 2020-

The current electric vehicles (EVs) face many challenges like limited charge capacity, low miles/charge, and long charging times. Herein, these issues are addressed by developing "energized composite," which is a multifunctional supercapacitor-based energy-storing carbon fiber reinforced polymer composite that can store supplemental electric energy and function as the body shell of EV's. This is achieved by developing a unique design, vertically aligning graphene sheets on carbon fiber electrodes and depositing metal oxides to obtain high energy density electrodes. A high-strength multilayer composite is fabricated using an alternate layer pattern configuration of epoxy and polyacrylamide gel electrolyte. The composite so developed …


Advanced Deep Learning Methodologies For Deepfake Detection, Aminollah Khormali Dec 2022

Advanced Deep Learning Methodologies For Deepfake Detection, Aminollah Khormali

Electronic Theses and Dissertations, 2020-

The recent advances in the field of Artificial Intelligence (AI), particularly Generative Adversarial Networks (GANs) and an abundance of training samples along with robust computational resources have significantly propelled the field of AI-generated fake information in all kinds, e.g., deepfakes. Deepfakes are among the most sinister types of misinformation, posing large-scale and severe security and privacy risks targeting critical governmental institutions and ordinary people across the world. The fact that deepfakes are AI-generated digital content and not actual events captured by a camera implies that they still can be detected using advanced AI models. Although the deepfake detection task has …


Ceria Defect Engineering Using Thin-Films/Ald And Biological Applications, Udit Kumar Dec 2022

Ceria Defect Engineering Using Thin-Films/Ald And Biological Applications, Udit Kumar

Electronic Theses and Dissertations, 2020-

Ceria nanostructures have been utilized for various engineering applications due to their unique defect structure, enabling them to have regenerative redox properties. The ability to shuttle between Ce3+ and Ce4+ oxidation states extends to unique properties. Defect level in ceria is usually expressed in the Ce3+/Ce4+ ratio. It can be achieved by varying the size(0 to 3D), morphologies, dopants, hetero-nanostructures, and external stimuli. However, it is still a challenge to have precise control over defect structures in the ceria lattice. The current study aims to explore the thin film deposition techniques for cerium oxide using ALD (Atomic layer deposition) and …


Synthesis, Characterization, And Modeling Of Thermo-Responsive Hydrogels With Improved Mechanical Strength And Swelling Kinetics, Marilu Ortiz Nieves Jan 2022

Synthesis, Characterization, And Modeling Of Thermo-Responsive Hydrogels With Improved Mechanical Strength And Swelling Kinetics, Marilu Ortiz Nieves

Electronic Theses and Dissertations, 2020-

Hydrogels have been extensively studied for use in applications such as tissue engineering, drug delivery systems, wound dressing, actuators, valves, and sensors in Micromechanical Systems (MEMS), among others. Thermo-responsive hydrogels in particular pose various advantages such as their capability to respond to an external stimulus and reverse the response when the stimulus is removed and the ability to imbibe a significant amount of solvent and increase their volume by over 1000%. Extensive research has been conducted to tune and improve hydrogel’s rate and degree of swelling and mechanical properties. Previous work showed that when synthetic clay (Laponite) is cross-linked with …


A Unified Tool For Adaptive Collocation Techniques Applied To Solving Optimal Control Problems, Bethany Kelly Jan 2022

A Unified Tool For Adaptive Collocation Techniques Applied To Solving Optimal Control Problems, Bethany Kelly

Electronic Theses and Dissertations, 2020-

In this work, a user-friendly MATLAB tool is introduced to solve nonlinear optimal control problems by applying collocation techniques using Coupled Radial Basis Functions (CRBFs). CRBFs are a new class of Radial Basis Functions combined with a conical spline r^5, which provides the advantage of insensitivity to the shape parameter while maintaining accuracy and robustness. To solve optimal control problems, software tools are often employed to implement numerical methods and apply advanced techniques to solving differential equations. Although several commercial software tools exist for solving optimal control problems, such as ICLOCS2, GPOPS, and DIDO, there are no options available that …


Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry Jan 2022

Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry

Electronic Theses and Dissertations, 2020-

Medical diagnostic devices are in high demand due to increasing cases of neurodegenerative diseases in the aging population and pandemic outbreaks in our increasingly connected global community. Devices capable of detecting the presence of a disease in its early stages can have dramatic impacts on how it can be treated or eliminated. High cost and limited accessibility to diagnostic tools are the main barriers preventing potential patients from receiving a timely disease diagnosis. This dissertation presents several devices that are aimed at providing higher quality medical diagnostics at a low cost. Brain function is commonly studied with systems detecting the …


Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian Jan 2022

Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian

Electronic Theses and Dissertations, 2020-

Smart grids and smart buildings are two highly interdependent energy infrastructure systems. Buildings rely on the grid to provide reliable power while their flexibility can also be utilized to enhance the reliability and efficiency of power system operations. The quantification of heating, ventilation, and air condition (HVAC) system flexibility is critical to the operations of both the grid and buildings in demand response (DR) programs. However, the flexibility quantification is challenging due to the non-linearity and non-convexity of thermal dynamics associated with HVAC components. This dissertation proposes a novel HVAC flexibility quantification method based on a semidefinite programming (SDP) formulation. …


Broadband Investigation Of The Pyrolysis Of Propane Using A Mir Optical Parametric Oscillator, Robert Greene Jan 2022

Broadband Investigation Of The Pyrolysis Of Propane Using A Mir Optical Parametric Oscillator, Robert Greene

Electronic Theses and Dissertations, 2020-

The chemistry of propane continues to play a pivotal role in today's power production technologies. As reliance on natural gas expands as greener cleaner fuels are sought throughout the world, especially as countries are attempting to transition away from traditional coal and crude-oil fired plants towards solar, wind, and hydro-electric sources. Natural gas, often seen as a bridge fuel between these two competing ends, has been in the recent past and for the foreseeable future will continue to play an important role in the energy sector. Among the components of natural gas, propane plays a key role in the chemistry …


Learning And Decision Making In Social Media Networks, Zhecheng Qiang Jan 2022

Learning And Decision Making In Social Media Networks, Zhecheng Qiang

Electronic Theses and Dissertations, 2020-

Social media is a virtual community where users share news, ideas, interests, and information. Learning the information diffusion dynamics and making decisions correspondingly, e.g., selecting the seed nodes to maximize the influence, have been widely applied to the areas of viral marketing and cyber security. In this dissertation, we study the problem of learning diffusion process, i.e., infection prediction, in social media networks utilizing both feature-based machine learning methods and mathematical model-based methods. For feature-based machine learning methods, the neighborhood information is treated as an important feature together with user profile and content similarity features. For model-based methods, two distinctive …


Data-Driven Diagnostics And Prognostics For Complex Systems: Methods And Applications, Junchuan Shi Jan 2022

Data-Driven Diagnostics And Prognostics For Complex Systems: Methods And Applications, Junchuan Shi

Electronic Theses and Dissertations, 2020-

Recent advances in artificial intelligence or machine learning have the potential to significantly improve the effectiveness and efficiency of diagnostic and prognostic techniques. The objective of this research is to develop novel data-driven predictive models with machine learning and deep learning algorithms that allow one to model the degradation, detect the faults, as well as predict the remaining useful life (RUL) of complex systems, including bearings, gearboxes, and Lithium-ion (Li-ion) batteries. First, an enhanced ensemble learning algorithm is developed to improve the accuracy of RUL prediction by selecting diverse base learners and features at different degradation stages. The proposed method …


Light Trapping Transparent Electrodes, Mengdi Sun Jan 2022

Light Trapping Transparent Electrodes, Mengdi Sun

Electronic Theses and Dissertations, 2020-

Transparent electrodes represent a critical component in a wide range of optoelectronic devices such as high-speed photodetectors and solar cells. Fundamentally, the presence of any conductive structures in the optical path leads to dissipation and reflection, which adversely affects device performance. Many different approaches have been attempted to minimize such shadowing losses, including the use of transparent conductive oxides (TCOs), metallic nanowire mesh grids, graphene-based contacts, and high-aspect ratio metallic wire arrays. In this dissertation I discuss a conceptually different approach to achieve transparent electrodes, which involves recapturing photons initially reflected by highly conductive electrode lines. To achieve this, light-redirecting …


Improving Urban Resilience And Sustainability Via Multi-Scale Urban Food-Energy-Water-Waste Nexus Analysis, Andrea Valencia Marin Jan 2022

Improving Urban Resilience And Sustainability Via Multi-Scale Urban Food-Energy-Water-Waste Nexus Analysis, Andrea Valencia Marin

Electronic Theses and Dissertations, 2020-

Urban sustainable development requires an in-depth and holistic understanding of the complex Food-Energy-Water-Waste (FEWW) nexus facing population growth, climate change, economic development, and pollution control. Following the United Nations (UN) 17 Sustainable Development Goals (SDGs), goal 11 aims for sustainable cities and communities to be resilient, sustainable, and safe cities to achieve social, economic, and environmental sustainability. Explicitly, SDG target 11.3 concentrates on inclusive and sustainable urbanization for sustainable planning and management. As the UN Food System program aims for inclusive, sustainable, and resilient network, promoting sustainable food systems becomes a necessity to echo social, economic, and environmental sustainability. The …


From Field To Failure: Detecting And Understanding Reliability Defects In Crystalline Silicon Photovoltaics, Dylan Colvin Jan 2022

From Field To Failure: Detecting And Understanding Reliability Defects In Crystalline Silicon Photovoltaics, Dylan Colvin

Electronic Theses and Dissertations, 2020-

Severe pollution levels and the growing influence of climate change have shown that dirty energy sources need renewable and sustainable replacements. The field of photovoltaics (PV) has grown substantially over the years from a niche space solar market to a commodity in large part due to improvements in reliability. Reliability of all materials in a PV module must be considered. The industry has seen an explosion of innovation in cell interconnection technologies with significant market penetration in the past several years. These emerging, less mature technologies require more reliability information to guide improvements. Degradation studies of long-term outdoor exposure and …


Assessing Public Perception And Proposing An Organized Questionnaire For The Deployment And Adoption Of Autonomous Vehicles, Md Rakibul Islam Jan 2022

Assessing Public Perception And Proposing An Organized Questionnaire For The Deployment And Adoption Of Autonomous Vehicles, Md Rakibul Islam

Electronic Theses and Dissertations, 2020-

Since the general public will play a central role in the evolution of AVs, research has been performed to assess their perception and acceptance of AVs. Nevertheless, the most potential users of AVs, i.e., young, students, and more educated people, have not received any particular focus in those studies. This research gap has motivated us to assess their perceptions. Extensive data analyses of the survey at the University of Central Florida with a sample of 315 reveal that on average 57% of the respondents were familiar with AVs, and about 44% of the respondents felt positive perceptions toward AVs. Around …


The Fluid Dynamics Of A Spanwise-Morphing Wing: An Experimental And Analytical Study, Kamlesh Joshi Jan 2022

The Fluid Dynamics Of A Spanwise-Morphing Wing: An Experimental And Analytical Study, Kamlesh Joshi

Electronic Theses and Dissertations, 2020-

The unsteady forces and fluid flow structure of a morphing wing are investigated for low Reynolds number (Re) flows, i.e., Re < 20,000. The morphing wing is designed to change shape in the spanwise direction in a controlled manner using internal actuation. The two types of wing morphing are studied in this work, i.e., spanwise bending and spanwise twisting. The wing morphing is named based on the overall shape of the wing after it is dynamically morphed.


Numerical Study Of Flow Of Supercritical Carbon Dioxide Inside Microchannels With Heat Transfer, Uday Manda Jan 2022

Numerical Study Of Flow Of Supercritical Carbon Dioxide Inside Microchannels With Heat Transfer, Uday Manda

Electronic Theses and Dissertations, 2020-

Heat transfer inside microscale geometries is a complex and a challenging phenomenon. As supercritical fluids display large variations in their properties in the vicinity of the critical point, their usage could be more beneficial than traditional coolants. This numerical study, in two parts, primarily focuses on the physics that drives the enhanced heat transfer characteristics of carbon dioxide (CO2) near its critical state and in its supercritical state. In the first part of the study, the flow of supercritical Carbon Dioxide (sCO2) over a heated surface inside a microchannel of hydraulic diameter 0.3 mm was studied using three-dimensional computational fluid …


Modeling And Simulation Of A Power Plant Boiler Including The Dynamics Of Swell And Shrink, Richard Perman Jan 2022

Modeling And Simulation Of A Power Plant Boiler Including The Dynamics Of Swell And Shrink, Richard Perman

Electronic Theses and Dissertations, 2020-

Renewables such as photovoltaics and wind turbines have seen consistent growth in markets across the globe. While renewables increase grid capacity and reduce the use of fossil fuels, their generation rates fluctuate subject to external factors. As the ratio of renewables to nonrenewables increases, so does variability of net load on intermediate and peaking power plants. Power plants with heat recovery steam generators (HRSG) constitute a significant proportion in these categories. There are several interconnected systems within HRSGs, including drum boilers which exhibit interesting transient phenomena known as swell and shrink. Improved understanding, dynamic modeling, and real-time simulation (RTS) of …


Search Space Reduction Techniques For Solution Of Combinatorial Optimization Problems In Power System., Ranadhir Sarkar Jan 2022

Search Space Reduction Techniques For Solution Of Combinatorial Optimization Problems In Power System., Ranadhir Sarkar

Electronic Theses and Dissertations, 2020-

Power system is vulnerable to disastrous climate events due to sequential or successive equipment failure. In this dissertation, the problem of identifying the critical k-transmission lines that fail one after another in quick succession, and the distribution system restoration problem using tie-lines/sectionalizing switches formulated as a mixed-integer non-linear programming problem (MINLP) that determines load shed under various k-line removal scenarios are solved. These problems are combinatorial that have huge search space, and solution through enumeration is intractable for large power systems. For reduction of search space, the following mathematical tools are derived, (i) two power flow methods due to k-transmission …


A Contingent Approach To Studying Technical Programs In The Public Aerospace Industry, Laura Segarra Jan 2022

A Contingent Approach To Studying Technical Programs In The Public Aerospace Industry, Laura Segarra

Electronic Theses and Dissertations, 2020-

Bibliometric evaluation of the literature indicates that a unified theory of program management does not yet exist. The vastly different definitions and implementations of programs across organizations and industries indicate that program management as an organizational concept is not well understood. As researchers have tried to make sense of various perspectives and definitions, it becomes clear that different kinds of programs exist, and further attention to their context is needed. While relationships between structural and environmental variables have been extensively researched in organizational studies, studies in program management are scant, lack incorporation of environmental variables relevant to programs and projects, …


Mixed-Criticality System Design For Real-Time Scheduling And Routing Upon Platforms With Uncertainties, Sudharsan Vaidhun Bhaskar Jan 2022

Mixed-Criticality System Design For Real-Time Scheduling And Routing Upon Platforms With Uncertainties, Sudharsan Vaidhun Bhaskar

Electronic Theses and Dissertations, 2020-

Unlike typical computing systems, applications in real-time systems require strict timing guarantees. In the pursuit of providing guarantees, the complex dynamic behaviors of these systems are simplified using models to keep the analysis tractable. In order to guarantee safety, such models often involve pessimistic assumptions. While the amount of pessimism was reasonable for simple computing platforms, for modern platforms the pessimism involves ignoring features that improve performance such as cache usage, instruction pipelines, and more. In this work, we explore routing and scheduling problems in real-time systems, where the uncertainties in the operation are carefully accounted for by complex models …


Design And Mechanical Characterization Of Functionally Graded Sandwich Beams Fabricated Via Additive Manufacturing, Timothy Grondin Jan 2022

Design And Mechanical Characterization Of Functionally Graded Sandwich Beams Fabricated Via Additive Manufacturing, Timothy Grondin

Electronic Theses and Dissertations, 2020-

Lightweight aerospace structures have been sought after since humans took flight in 1903, making major strides in NASA's pursuit of the moon with the development of sandwich panel composites. Sandwich structures typically consist of two stiff phases (i.e., face sheets) separated by a lightweight phase (i.e., core), which are stacked together through adhesive layers. Such a structural arrangement provides a high stiffness-to-weight ratio and is often used in applications where weight saving is critical. Functionally Graded Materials (FGMs), refer to multifunctional materials, which contain a spatial variation of composition and/or microstructure for the specific purpose of altering thermal and structural …


Generative Modeling Of Human Behavior: Social Interaction And Networked Coordination In Shared Facilities, Saumya Gupta Jan 2022

Generative Modeling Of Human Behavior: Social Interaction And Networked Coordination In Shared Facilities, Saumya Gupta

Electronic Theses and Dissertations, 2020-

Urbanization is bringing together various modes of transport, and with that, there are challenges to maintaining the safety of all road users, especially vulnerable road users (VRUs). Therefore, there is a need for street designs that encourages cooperation and resource sharing among road users. Shared space is a street design approach that softens the demarcation of vehicles and pedestrian traffic by reducing traffic rules, traffic signals, road markings, and regulations. Understanding the interactions and trajectory formations of various VRUs will facilitate the design of safer shared spaces. It will also lead to many applications, such as implementing reliable ad hoc …


Air Force Pilot's Recognition About The Effectiveness Of Active Noise Cancellation On Hearing Health, Performance, And Aviation Safety, Kyungtaek Hwang Jan 2022

Air Force Pilot's Recognition About The Effectiveness Of Active Noise Cancellation On Hearing Health, Performance, And Aviation Safety, Kyungtaek Hwang

Electronic Theses and Dissertations, 2020-

The purpose of this thesis is to suggest the application of Active Noise Cancellation in Air Force pilot headset and helmet not only to reduce noise-induced hearing damage, but also to enhance pilot performance and aviation safety. Despite the recent advances of sound treatment technology, the interior sounds of a military aircraft exceed the damage risk criterion of 8 hrs/day exposure. Air Force pilots are flying under the extreme condition where noise is severe and prevalent. The exposure to noise can lead to permanent hearing loss, stress and fatigue, unintelligible communication, and deterioration of speech perception and recall. With all …


Flame-Generated Turbulence For Flame Acceleration And Detonation Transition, Rachel Hytovick Jan 2022

Flame-Generated Turbulence For Flame Acceleration And Detonation Transition, Rachel Hytovick

Electronic Theses and Dissertations, 2020-

Detonations are a supersonic mode of combustion witnessed in a variety of applications, from next-generation propulsion devices to catastrophic explosions and the formation of supernovas. Detonations are typically initiated through the deflagration to detonation transition (DDT), a detailed process where a subsonic flame undergoes rapid acceleration increasing compressibility until a hotspot forms on the flame front inciting a detonation wave to form. Due to the complex nature of the phenomena, DDT is commonly investigated in three stages – (i) preconditioning, (ii) detonation onset, and (iii) wave propagation and stability. The research presented explores each of these stages individually, with a …