Engineering Commons^™

Machine Learning Approaches To The Exploration Of Ammonia Synthesis Catalysts Utilizing Experimental Data, Rasika Jayarathna

Theses and Dissertations

Traditional heterogeneous catalyst discovery process relies upon human expert-guided experiments based on domain knowledge and human intuition supported by catalyst characterization. However, this process is time and resource-consuming and suffers from human bias. Machine learning (ML) models trained on experimental data have the potential to significantly accelerate this discovery process by guiding experiments to optimize the catalyst performance and increase the understanding of the catalysts. Ammonia synthesis catalysts are a class of catalysts widely investigated in the literature, which has generated decades of experimental data. Moreover, ammonia has been gaining attention since it can be used as a carbon-free next-generation …

Development Of A Large Format Additive Manufacturing System Based On An Off-The-Self Pellet Extruder, Aywan Das

Theses and Dissertations

Large Format Additive Manufacturing (LFAM), or Big Area Additive Manufacturing (BAAM), was introduced to resolve the limitations of the low deposition rate, low scalability, and therefore long print times, of traditional 3D printing methods when applied to the manufacturing of large structures and tooling. LFAM can be used to overcome the high conventional tooling costs of large structures. However, even with robotic setups, LFAM still mainly relies on quasi-planar, 2.5D printing strategies. This fails to reap the advantages of multi-axis printing, such as improved adhesion, reduced support material use, and the ability to create complex curved surfaces. In this research, …

Improving Tcp Performance Using P4-Programmable Data Planes, Jose Antonio Gomez Gaona

Theses and Dissertations

The Transmission Control Protocol (TCP) forms the foundation of reliable end-to-end communication and is widely used by many applications for efficient data transfers across the Internet. TCP relies on various congestion control algorithms (CCAs) to manage its response to network congestion. These algorithms ensure fairness among competing flows and optimize the use of available bandwidth. However, since TCP is deployed within end hosts, its capacity to attain visibility of network events is constrained. This limitation arises from the closed nature of non-programmable network devices, which prevents researchers from exploring customized actions in response to network events. Recently, the emergence of …

Parallel Communications In Single-Core Optical Fibers Utilizing Spatial Domain Multiplexing And Wavelength Division Multiplexing, Mingxuan Tu

Theses and Dissertations

This endeavor proposes a hybrid parallel optical communication architecture in single-core fibers combining WDM in O-band (1270 nm, 1310 nm, 1310 nm, and 1330 nm) and two-channel SDM. The proposed architecture applies carefully designed delays in each propagating channel to achieve synchronization and, therefore, realizes parallel transmission in single-core fibers without the help of Serializer/De-serializers (SerDes). A mathematical model of SDM, calculations on delays between each optical channel, simulation of the hybrid architecture, experimental setup, and the testing and analysis of channel performance have been provided. A design of a photonic integrated circuit based on thin film lithium niobate electro-optic …

Development Of A Mechanical Boot For Prevention Of Deep Vein Thrombosis In Outpatients, Julian David Trevino

Theses and Dissertations

This work presents the development of a mechanical boot designed to prevent Deep Vein Thrombosis (DVT) in high-risk individuals such as those who have just had major procedures. DVT is a serious condition characterized by the formation of blood clots in the deep veins, particularly of the lower limbs, which can lead to life-threatening complications if not adequately addressed. The mechanical boot utilizes the principle of Continuous Passive Motion (CPM) to facilitate blood flow in the lower extremities, thereby mitigating the risk of clot formation. Through a combination of mechanical engineering, biomedical research, and user centered design, the project outlines …

Investigation Of Ethane Dehydrogenation And Hydrogenolysis On Pt(111), Pt(211) And Pt(100): Bayesian Quantification And Correction Of Dft-Based Enthalpic And Entropic Uncertainties, Mubarak Bello

Theses and Dissertations

Computational investigations of heterogeneously catalyzed reactions using density functional theory (DFT) are often inaccurate, largely due to uncertainties in the choice of DFT functional (enthalpic uncertainty) and approximations for modeling adsorbate movement along the catalyst surface (entropic uncertainty). This work illustrates that both uncertainties are significant in the investigation of the ethane dehydrogenation (EDH) and hydrogenolysis on Pt catalysts by considering the complete deconstruction of ethane on Pt(111), Pt(211), and Pt(100) using microkinetic modeling (MKM). Hence, this work uses both non-calibrated and Bayesian calibrated MKMs to quantify and correct inaccuracies in macroscopic properties due to both uncertainties. A Bayesian approach …

Exploring Shape Dependency Of Catalysts For Chemical Reactions, Kaveh Shariati

Theses and Dissertations

Recent advancements in the synthesis of nanoparticles, particularly one-dimensional (1D) nanoparticles, have significantly enhanced the catalytic activity of various processes by enabling precise control over their morphologies and exposing unique crystallographic facets. The shape of nanoparticles is closely linked to their chemical, physical, electrical, optical, magnetic, and catalytic properties. This dissertation investigates the impact of 1D nanoparticle catalysts on two distinct and well-known chemical reactions. In the first part of the study, we explore the catalytic activity and selectivity of silver catalysts in the ethylene epoxidation reaction, which are intrinsically linked to their faceting. Silver nanowire catalysts representing Ag(100) and …

Design And Development Of A Direct Medium Voltage Solar Pv Resonant Inverter, Parthkumar Sureshkumar Bhuvela

Theses and Dissertations

In a grid-tied photovoltaic (PV) system connected to a medium voltage (MV) grid, an inverter is generally employed with a line frequency transformer (LFT) to connect to the grid. These LFTs are large in size and weight, exhibit high cost and losses. In recent studies, the LFTs replaced by are by (high frequency transformer) HFT embedded in DC-DC converters. These DC-DC converters are used to boost voltage levels and DC-AC inverters are employed for MV inversion. This leads to high frequency switching at MV which increases losses in inversion stage. In this study, a novel MV grid-connected solar PV inverter …

Study On Pilot Response Time To Reject Takeoff With One Engine Inoperative (Oei), Lydia Savitri Scrivens

Theses and Dissertations

The FAA regulation 14 CFR § 25.109 defines accelerate-stop testing for transport-category multiengine aircraft. It specifies that testing must include 2-second distance equivalent at engine failure speed VEF to simulate time taken for pilot to reject takeoff. However, pilot response time is widely debated. The purpose of this study is to determine pilot response time in rejecting a takeoff due to the failure of one engine during the takeoff roll.

Seven multiengine rated pilots participated in this study, which was conducted in a Baron 58 in the X-Plane 12 flight simulator. During the recruiting process, test subject candidates provided their …

Innovative 4d Printing Of Biomimetic Collagen-Tcp Scaffolds For Bone Regeneration, Karly Morgan Liebendorfer

Theses and Dissertations

Bone tissue engineering (BTE) is a promising alternative approach to autografts and allografts when treating various bone diseases and disorders. BTE enables the fabrication of biocompatible, biomimetic, and osteo-stimulating constructs for the repair and regeneration of damaged bone tissue. The native bone environment primarily consists of anisotropic type 1 collagen (organic) and hydroxyapatite nanocrystals (inorganic). Composite biomimetic scaffolds fabricated by combining collagen with bioceramics have shown immense promise for BTE applications. Prior work has reported on different biofabrication methods to synthesize collagen-based composite scaffolds for use in BTE applications. However, to date, a customizable 3D composite scaffold that resembles the …

Increasing Optical Channel Capacity By Integrating Pam4 Modulation With Wavelength Division Multiplexing And Spatial Domain Multiplexing, Swaroopini Harish

Theses and Dissertations

Spatial division multiplexing (SDM) is a technique used in telecommunications and networking to increase data transmission capacity over optical fiber communication channels. This multiplexing technique spatially reuses optical frequencies by allocating different spatial locations for inputs based on their inject angles. The signals travel in a helical pattern within the carrier fiber and exit as concentric rings. SDM enables more efficient utilization of available bandwidth and improved communication performance. In four-level pulse amplitude modulation (PAM4), each symbol represents a combination of four possible signal levels instead of the two levels in binary modulation. The four levels are denoted in different …

Enhancement Of Polytetrafluoroethylene-Polyvinyl Alcohol Nanofibers Triboelectric Effect With Carboxylic Functionalized Multiwalled Carbon Nanotubes Coating, Fernando Viesca

Theses and Dissertations

In this study, we fabricated a TENG using Forcespinning® (FS) Polytetrafluoroethylene microfibers (FS-PTFE-MFs) and Electrospun (ES) Polyvinyl alcohol nanofibers (ES-PVA-NFs). The FS-PTFE-MFs were physically linked with functionalized carboxylic multiwall carbon nanotubes (MWCNTs-COOH) employing water dispersions. MWCNTs-COOH were dispersed using three different surfactants: Sodium Dodecyl Sulfate (SDS), Sodium dodecylbenzenesulfonate (SDBS), and Triton X-100 (TX-100). Coated FS-PTFE-MFs were then characterized using a field emission scanning electron microscope (FESEM) with an energy dispersive X-ray spectroscopy (EDS) attachment and Fourier-transform infrared spectroscopy (FTIR). While no significant difference in performance was observed with different surfactants, electrical results of the TENG recorded a notable enhancement of …

Simulation Of A Passive Osmosis-Integrated Electrolyzer For Seawater Electrolysis, Masoomeh Ghasemi

Theses and Dissertations

Efforts to develop direct seawater electrolysis technology have been ongoing due to the need for pure water in electrolysis and the abundance of seawater. However, progress has been hampered by several issues, including competition with the chlorine evolution reaction, higher membrane resistance, corrosion of electrodes, and scaling from multivalent cations [1]. To avoid these issues, our project has proposed a new reactor that integrates passive osmosis (extracting fresh water from seawater) with electrolysis. In this thesis, we will discuss the operation of the osmosis-integrated electrolyzer and show theoretical predictions of the osmotic pressure differential and water flux/velocity profiles under different …

Investigating The Effects Of Calcitonin Gene Related Peptide On Heart Failure And The Gut Microbiome, Talia Charlotte Kepniss

Theses and Dissertations

Heart failure affects millions of people worldwide with current available treatments that are limited in their efficacy. The financial burden for care of those with heart failure is over 20 billion dollars in the US alone. Calcitonin gene related peptide has demonstrated cardioprotective and powerful vasodilator effects. In this study our objective is to prevent the onset of heart failure and treat early stages of heart failure with injections of calcitonin gene related peptide in C57BL/6 mice. In order to model heart failure, experimental mice underwent a transverse aortic constriction surgery. Echocardiograms and fecal collections were completed to observe changes …

Enabling Novel Nanopore Sensing Approaches For Personalized Medicine Through Chemical Modifications To Analytes, Zehui Zhang

Theses and Dissertations

Nanopore sensors have garnered significant attention recently, not only for their groundbreaking advancements in single-molecule DNA sequencing but also for their diverse applications in stochastic sensing, single-molecule chemistry, and protein unfolding. The interaction of single molecules with the nanopore sensing interface leads to characteristic ionic current modulations, reflecting the composition, charge, distribution, structure, and sequence of the translocating molecule. With the electrical resistive pulse nanopore sensing, its single-molecule sensitivity and specificity have opened doors to numerous potential applications in personalized medicine. I will discuss recent advancements in the sensitivity and specificity of personalized medicine using nanopore sensors, focusing on proteomic …

Surface Acoustic Waves-Based Point-Of-Care Biosensor, Debdyuti Mandal

Theses and Dissertations

A biosensor is an analytical tool consisting of biologically active material used in close conjunction with a device that converts a biochemical signal into a quantifiable electrical signal. The early detection of the disease biomarkers can enhance the increased curability of the disease, reduce healthcare costs, and finally, improve the quality of life for patients. Thus, for the following purpose, there is always a need for an effective biosensor as a diagnostic device. The biosensor typically consists of an actuator, a bio-recognition component, and a transducer that converts captured signals into a meaningful display. The bio-recognition component uses biomolecules to …

Quantifying Extreme Events: Applications Of Probabilistic Methods To Quantify Riverine And Coastal Flood Dynamics In South Carolina And Neighboring Coastal Communities, Ryne Phillips

Theses and Dissertations

Extreme flood events have been persistent throughout history and have challenged human populations around the globe. Over time, scientists and engineers have developed tools and technology to support flood risk management. Most, if not all, of these tools rely on some form of the field of stochastic hydrology. Stochastic hydrology is a broad discipline, but the overarching principle is to use statistical and data-driven techniques to develop an understanding of one or more hydrologic variables (e.g., flood flow or peak storm tide). However, the need for large sample sizes of data that offer insight into all possible combinations of outcomes …

Control Optimization And Adaptive Tuning Of Droop Controlled Systems For Dc Bus Stability Via Terminal Impedance Shaping, Andy Wong

Theses and Dissertations

Many traditional AC systems have been moving towards DC in recent decades due to advancements in power electronics and semiconductor devices. DC power distribution systems, such as DC microgrids, have become increasing popular due to energy efficiency, resiliency, and renewable energy integration. However, with such systems which commonly utilize droop control, comes an issue of system stability due to the interconnection of multiple feedback-controlled converters to a common bus. To combat this issue, this thesis proposes a control optimization and adaptive tuning approach for maintaining DC bus stability and dynamic performance of droop controlled systems. First, a terminal impedance model …

Multidimensional Simulation Of Cool Diffusion Flame, Ejaz Ahmed

Theses and Dissertations

Understanding the behavior of spherical cool diffusion flames in microgravity conditions is crucial for advancing combustion research. This knowledge has significant implications for both fundamental science and practical applications, such as spacecraft fire safety and the development of advanced, high-efficiency engines that benefit from low-temperature chemistry. Spherical cool diffusion flames are typically characterized by peak temperatures between 500 and 1000K and are often followed by the radiative extinction of a hot flame. Some low-temperature ignitions can sustain indefinitely at around 700K, leading to chain-branching pathways that produce intermediate species such as C2H4, H2O2, HO2, CH2O, CH3O, and HCO. In some …

Accelerating Numerical Modeling And Optimization Of Structural Mechanical Systems, Fatemeh Hashemian

Theses and Dissertations

This research proposal presents Bayesian optimization and reduced order modeling methods to accelerate numerical analysis and design of structure mechanical system. First, a holistic framework of Bayesian optimization (BO) based on parameterized numerical models and genetic algorithm-guided adaptive sampling is developed to automate and accelerate the design of a front-loading washing machine. The research aims to address challenges associated with the model parameterization and global optimization and design. A multibody dynamics model of the washing machine incorporating a set of 9 key design variables is developed. The design variables are implemented to enable automated modifications of the dynamics model for …

Applications Of Catalytic Ammonia Chemistry: From Low-Pressure Ammonia Synthesis To The Decomposition Of Tritiated Ammonia As A By-Product Of Magnetically Confined Nuclear Fusion, Jennifer Kules Naglic

Theses and Dissertations

Ammonia is the 2nd most produced chemical in the world with vital importance for its use in fertilizer as the global population has grown in accordance with the industrialization of NH3. While 80% of NH3 produced goes to fertilizer, it has gained attention recently as a hydrogen storage and transportation vessel. Industrially, NH3 is produced at high temperatures and pressures which in turn require high electrical input. Turning to a green NH3 cycle with low temperature and pressure membrane reactors for both NH3 synthesis and decomposition would allow for much lower energy input as well as a renewable energy to …

Patient-Specific Hemodynamic Modeling For Optimizing Left Ventricular Assist Device And Right Heart Health, Holly Felice Grant

Theses and Dissertations

LVAD speed optimization is essential for efficient LVAD therapy and to minimize complications. However, the ideal LVAD speed is unknown and must be tailored for each patient. The interplay between the LVAD, systemic, and pulmonary circulations is critical and should be considered during optimization. A computational hemodynamic model that can be tailored for each patient may provide clinicians with useful guidance and reduce the need for repeated invasive studies. This study sought to customize and evaluate a patient-specific LVAD hemodynamic optimization model.

We conducted a retrospective analysis on 25 patients implanted with HM3 and who underwent right heart catheterization (RHC) …

Evaluating The Influence Of Evtol Pilot Interface Visual Density And Information Density On Pilot Situation Awareness, Workload, And Search Performance, Bhoomin Bhupendrabhai Chauhan

Theses and Dissertations

The purpose of the current study was to investigate the influence of levels of visual density (VD) and information density (ID) of an electrical vertical take-off and landing (eVTOL) aircraft pilot interface on pilot situation awareness (SA), workload, and search performance. An eVTOL aircraft is a novel aircraft design that is able to perform vertical take-off and landing similar to a rotorcraft and transition to a forward flight, similar to a fixed-wing aircraft. These aircraft are envisioned to operate in urban environments at lower altitudes, necessitating efficient, clear, and concise pilot interfaces to ensure safety and operational effectiveness. The study …

Engine Performance Of An Electric Airplane With Partial Battery Capability, Hannah Yasmine Scrivens

Theses and Dissertations

As electric aircraft are developed and certified, knowledge of electric aircraft performance during complete or partial battery failures can be useful to determine an aircraft’s limitations and capabilities of completing an emergency landing, especially during takeoff and low-altitude climbs, as well as fully characterizing the potential aircraft performance. The results of this research will be useful in developing regulations and procedures pertaining to energy reserves and emergencies. This paper presents the results of a Pipistrel electric airplane climb power ground test that was conducted by the author and Florida Tech faculty. In the test, one of the airplane’s batteries was …

Manufacturing Of Aligned Electrospun Nanofiber Yarns For Their Enhanced Mechanical And Piezoelectric Properties, Adaugo Mary-Frances Enuka

Theses and Dissertations

Electrospinning is a widely used technique for producing nanofibers with diverse applications. This method uses polymer solutions and strong electric fields to generate nano-sized fibers with unique properties. This study presents a novel manufacturing approach that enables the production of electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber yarns using an automated parallel track system and an adjustable roll-to-roll collector. This research examines the impact of an automated post-drawing system on the polymer chain orientation, crystallinity, tensile strength, morphology, and piezoelectric properties of PVDF-HFP nanofiber yarn. The results reveal that the post-drawing process significantly improves molecular alignment, increases tensile strength, and enhances the …

Matrix Processing With Photonic Analog Computing, James Michael Garofolo

Theses and Dissertations

In the digital age, a wide variety of engineering problems have been solved, to a great deal of success, by digital computing techniques. The flexibility of software and relatively low cost of digital computing hardware make it an ideal starting point for solving a majority of tasks, and the numerical stability of software solutions make it highly appealing as the major workhorse for computational tasks. Despite this, many problems are actually suboptimally solved by digital methods, leading to systems with high latency, low throughput, power hungry parallel processing units and an excess of memory for discretizing sensor inputs. Computational photonic …

Repair And Surface Functionalization Of Fiber Reinforced Polymer Composites By Cold Spray, Ibnaj Anamika Anni

Theses and Dissertations

Fiber-reinforced polymer composites are widely used in industries and applications such as energy, automotive, defense, and aerospace. This study investigates the application of polymer cold spray, an emerging additive manufacturing process, for coating and repair of fiber-reinforced polymer (FRP) composites. The research starts with feasibility studies focused on the cold spray deposition of thermoplastic nylon-6 particles on woven glass fiber-reinforced composites (GFRP). A parametric study determines critical process parameters window, ensuring successful deposition and bonding without compromising the macroscale mechanical behavior. These findings indicate that the cold spray process does not adversely affect the fiber integrity or surface quality of …

Chemotherapy Drug Release From Hollow Core Polyethyleneimine Nanoparticles, Brian Boyle

Theses and Dissertations

Novel anticancer delivery vehicles are arising from engineered nanostructured materials. This work involved the synthesis, characterization, and release of novel hollow core polymeric nanoparticles (HCPNPs) for controlled drug delivery. Polyethyleneimine (PEI) was bound to AuNPs, forming polymer-shell nanoparticles with dissolution of the gold core via iodine forming HCPNPs with drug intercalated DNA bound to the surface. A high density (85 molecules/particle) of DNA intercalated with daunorubicin was conjugated. Particles were spherical with an average diameter of 105.7 ± 17.3 nm and zeta potential of 20.4 ± 3.54 mV. We hypothesize the DNA backbone electrostatically condensed to the primary amines on …

Investigating The Feasibility And Mechanisms Of Cold Spray Deposition Of Polymer-Based Powders On Fiber-Reinforced Composite Substrates, Nicholas Beau Mennie

Theses and Dissertations

Fiber-reinforced composites have become important structural components in industries such as aerospace and energy due to their high mechanical strength and relatively light structural weight. However, during operation, these materials can be prone to impact damage and disintegration. Effective protection via metalization and repair of composites would, therefore, reduce the cost and time for replacement parts. Polymer-based cold spray, while a relatively new technique, can be utilized to metalize and possibly repair composite materials subjected to impact-induced damage. In this work, studies involving polymers and composite cold spray were performed to enable the process of safeguarding, enhancing, or repairing various …

Design, Fabrication, And Characterization Of Multifunctional Cellular Structures For Enhanced Impact Energy Mitigation Performance, Kazi Zahir Uddin

Theses and Dissertations

This dissertation investigates the relationship between the structural design of cellular solids and their macroscopic behavior and focuses on the customization of properties through advanced fabrication techniques. The concepts of density gradation and their integration in both non-ordered and ordered cellular structures have been proposed. The investigation focuses on the development of functionally graded foam materials (FGFMs) and mechanical metamaterials to obtain tunable mechanical performance. One significant focus is the fabrication of density-graded foam stacks with various interface adhesives. From the insights gained from the study of interfaces in density-graded foams, certain design and fabrication principles are applied to enhance …