Engineering Commons^™

Flame Stabilization Of A Premixed Jet In Vitiated Coflow, Tyler Owens

Theses and Dissertations--Mechanical and Aerospace Engineering

Premixed staged combustion in gas turbine engines can reduce emissions by lowering peak flame temperatures but can also lead to different stability characteristics when compared to traditional combustors. High pressure ratio and subsequently high temperatures can lead to conditions suitable for both autoignition and premixed flame propagation in an environment where spatial fuel/air variations are present.

An experimental facility which issues a premixed jet into a coflowing vitiated mixture was studied to examine the stability behavior, resulting in a lifted flame. The effective ignition delay observed flame was much greater than homogeneous ignition delay calculations for the same conditions. It …

Development And Application Of Novel Sound Absorbers, Weiyun Liu

Theses and Dissertations--Mechanical and Aerospace Engineering

The sound absorbers in most common use today are porous materials like fibers and foams. This work examines three alternatives to porous absorbers: microperforated panels, acoustic fabrics, and additively manufactured absorbers. The research is a combination of design, measurement and characterization of their properties, and analysis.

Microperforated panels are thin metallic or plastic panels with sub-millimeter size holes or perforations. Sound absorption can be tuned by adjusting the spacing between the panel and a cavity behind the panel. Several different configurations were considered where the geometry behind the panel was divided up into channels of varying length and cross-sectional area. …

Development Of Micro-Scale High Aspect Ratio Patterned Features With Electroless Nickel Plating, Lorli Smith

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis describes a novel method designed to pattern high aspect ratio metallic microscale features using a modified photolithography and electroless nickel plating process. This method utilizes modified photolithography techniques to create a polymer mold that is used to control the location of metal deposition on substrate during electroless nickel plating. In order to generate high aspect ratio mold features, a multiple spin-step process was developed to deposit thick layers of SU-8 photoresist, and inclined lithography was also used to generate tapered sidewalls that could help aid mold removal after plating. Results from electroplating experiments were evaluated using a Zygo …

Development Of Universal Solver For High Enthalpy Flows Through Ablative Materials, Umran Duzel

Theses and Dissertations--Mechanical and Aerospace Engineering

Atmospheric entry occurs at very high speeds which produces high temperature around the vehicle. Entry vehicles are thus equipped with Thermal Protection Systems which are usually made of ablative materials. This dissertation presents a new solver that models the atmospheric entry environment and the thermal protection systems. In this approach, both the external flow and the porous heat shield are solved using the same computational domain. The new solver uses the Volume Averaged Navier-Stokes Equations adapted for hypersonic non-equilibrium flow, and is thus valid for both domains. The code is verified using analytical problems, set of benchmarks and also a …

Bacterial Cell Wall Characterization Via Atomic Force And Confocal Microscopy, Joree Sandin

Theses and Dissertations--Mechanical and Aerospace Engineering

Poor oral hygiene is a severe global health issue, with about 44% of the Earth’s population suffering from untreated tooth decay, accounting for over $100 billion dollars spent on dental services per year in the United States, alone. Manual treatments, such as brushing, flossing, or swishing with antiseptic rinse are the main ways to alleviate harmful bacteria that cause these oral health problems. Streptococcus mutans (S. mutans) is a group of highly antibiotic, Gram-positive bacteria that heavily contribute to oral cavities, plaque build-up, and potential loosening or loss of dental implants if a biofilm develops. Currently, the mechanism …

Carbon Oxidation At The Atomic Level: A Computational Study On Oxidative Graphene Etching And Pitting Of Graphitic Carbon Surfaces, Simon Schmitt

Theses and Dissertations--Mechanical and Aerospace Engineering

In order to understand the oxidation of solid carbon materials by oxygen-containing gases, carbon oxidation has to be studied on the atomic level where the surface reactions occur. Graphene and graphite are etched by oxygen to form characteristic pits that are scattered across the material surface, and pitting in turn leads to microstructural changes that determine the macroscopic oxidation behavior. While this is a well-documented phenomenon, it is heretofore poorly understood due to the notorious difficulty of experiments and a lack of comprehensive computational studies. The main objective of the present work is the development of a computational framework from …

Fabrication And Characterization Of Nickel Plated Micro-Resonators For Noncommutative Orientation Control In Microrobots, Marc Manheim

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis describes a procedure for fabricating arrays of microstructures out of SU-8 photoresist and nickel, which was developed with the goal of yielding microrobots capable of 1D rotation byway of magnetically-induced beam vibration that could be used for non-commutative orientation control. Several multi-layer geometries were designed, fabricated, tested and refined. In this process, micro-adhesion of multiple SU-8 layers was also studied. A method for depositing nickel via electroless plating was also developed, tested and characterized. While no microrobots were shown to produce rotation, the final results included beams that were capable of magnetically-induced vibration when subjected to an AC …

Expanded Predictive Equation For Dc Arc-Flash Incident Energy In 125v Battery Systems, Austin Gaunce

Theses and Dissertations--Electrical and Computer Engineering

Arc-flash is a dangerous phenomenon that can occur during an arcing fault in an electrical system. People nearby may be subjected to extreme heat, light, pressure, and sound. Research regarding arc-flash has focused primarily on AC arc-flash due to the prevalence of AC electricity in the grid. However, the grid has begun to integrate more DC electrical sources as a result of decentralization efforts and environmental concerns. The increased proliferation of DC electrical sources demands research into DC arc-flash to assess the hazard as low-voltage DC sources have already become commonplace. Some DC arc-flash models have been produced to estimate …

Ecosystem Of Bagged Grain Stored Under Naturally Ventilated Warehouse: Analysis And Modelling, Michael Ayodele Omodara

Theses and Dissertations--Biosystems and Agricultural Engineering

Grain in Africa and indeed most developing parts of the world are stored in polypropylene or jute bags arranged in stacks of varied dimensions in naturally ventilated warehouses. This practice is, however, associated with high postharvest losses due to poor temperature and moisture management during storage. This constitutes a major economic and food security challenge in these countries. Therefore, this study characterizes changes in moisture content and temperature occurring in a stack of bagged corn by determining the permeability of bag materials that influence moisture transfer and developing a mathematical model of heat and mass transfer which incorporates the unique …

Characterizing And Predicting The Antimicrobial Properties Of Lignin Derivatives, Ryan Kalinoski

Theses and Dissertations--Biosystems and Agricultural Engineering

Due to the overuse of antibiotics in our society, there has been a steady rise in highly antimicrobial-resistant bacteria in the last decade. This has created a renewed interest in natural phenolic compounds for antimicrobial discovery amongst the scientific community. To this end, lignin is the most abundant naturally occurring phenolic polymer on earth and has already been known to have antimicrobial properties due to its polyphenolic structure. In addition, lignin is considered a major waste product for lignocellulosic biorefineries, and its valorization into value-added products will generate extra profit for a biorefinery, making biofuels less expensive, increasing their marketability …

Physicochemical Characterization, Structural Determination, And Molecular Dynamic Modeling Of Proso Millet Proteins For Enhanced Food Functionality, Felix Akharume

Theses and Dissertations--Biosystems and Agricultural Engineering

More than one-third of Americans today incorporate plant-based protein into their diet and about 40% believed that plant-based protein is healthier than animal protein, especially Millennials. The increasing global demand for plant-based proteins driven by the high cost of animal proteins, consumers’ desire for lean protein, vegetarianism, and the need for more sustainable green protein products have necessitated research into alternate emerging and underutilized sources of protein to complement or supplement the major plant protein in the market- soy, pea, and gluten. Therefore, this dissertation is focused on the valorization of the proteins in proso millet. Specifically, this work focused …

Effects Of Watershed Disturbances And River-Tributary Confluences On Sedimentation Dynamics In The Upper Ohio River Basin, Ciara Pickering

Theses and Dissertations--Biosystems and Agricultural Engineering

Harmful algal blooms (HABs) are of increasing concern in the Ohio River Basin. Fine sediment dynamics in riverine environments are increasingly recognized to play important roles in proliferation and toxicity of Microcystis blooms. Further, the fate of sediment at confluences of tributaries and the main river system are important zones for sediment retention and transient storage. The objective of this study was to improve understanding of watershed sediment loading dynamics and backwater inundation influencing sedimentation within confluence watersheds. The study site is the Fourpole Creek watershed in Huntington, WV which is a disturbed forested watershed impacted by a backwater confluence …

Automated Testing And Bug Reproduction Of Android Apps, Yu Zhao

Theses and Dissertations--Computer Science

The large demand of mobile devices creates significant concerns about the quality of mobile applications (apps). The corresponding increase in app complexity has made app testing and maintenance activities more challenging. During app development phase, developers need to test the app in order to guarantee its quality before releasing it to the market. During the deployment phase, developers heavily rely on bug reports to reproduce failures reported by users. Because of the rapid releasing cycle of apps and limited human resources, it is difficult for developers to manually construct test cases for testing the apps or diagnose failures from a …

Fourier Transform Infrared Spectroscopy (As A Rapid Method) Coupled With Machine Learning Approaches For Detection And Quantification Of Gluten Contaminations In Grain-Based Foods, Abuchi Godswill Okeke

Theses and Dissertations--Biosystems and Agricultural Engineering

Cross-contamination between food grains during harvesting, transportation, and/or food processing is still a major issue in the food industry. Due to cross-contact with gluten-rich grains (wheat, barley, and rye grains), gluten can get into food that’s naturally free from gluten and thus may not be safe for consumption for people susceptible to gluten-related disorders such as celiac disease, wheat allergy, gluten intolerance or sensitivity. The conventional method of gluten detection is cumbersome, time-consuming, and requires well-trained personnel. Therefore, there is a need for a rapid and equally effective technique to authenticate gluten contamination in foods. This research work explored the …

Characterization And Enzyme Engineering Of Laccases Towards Lignin Valorization In Aqueous Ionic Liquids, Joseph Stevens

Theses and Dissertations--Biosystems and Agricultural Engineering

Lignin is one of the most abundant polymers found in nature, making up 15 – 40% of the weight of terrestrial biomass. Due to the structural and monomeric heterogeneity of lignin, it is recalcitrant thermochemical and biological valorization methods. Converting lignin to value-added products via sustainable and cost-effective pathways will reduce waste and add value to future cellulosic biorefineries. Biological methods for lignin valorization (e.g. lignin degrading enzymes or microbes) is limited by low lignin solubility in biocompatible solvents, resulting in low product yield. Recent reports on biocatalysts for lignin valorization have focused on the lignolytic multicopper oxidase laccase, …

Metadata Management For Clinical Data Integration, Ningzhou Zeng

Theses and Dissertations--Computer Science

Clinical data have been continuously collected and growing with the wide adoption of electronic health records (EHR). Clinical data have provided the foundation to facilitate state-of-art researches such as artificial intelligence in medicine. At the same time, it has become a challenge to integrate, access, and explore study-level patient data from large volumes of data from heterogeneous databases. Effective, fine-grained, cross-cohort data exploration, and semantically enabled approaches and systems are needed. To build semantically enabled systems, we need to leverage existing terminology systems and ontologies. Numerous ontologies have been developed recently and they play an important role in semantically enabled …

Estimating Free-Flow Speed With Lidar And Overhead Imagery, Armin Hadzic

Theses and Dissertations--Computer Science

Understanding free-flow speed is fundamental to transportation engineering in order to improve traffic flow, control, and planning. The free-flow speed of a road segment is the average speed of automobiles unaffected by traffic congestion or delay. Collecting speed data across a state is both expensive and time consuming. Some approaches have been presented to estimate speed using geometric road features for certain types of roads in limited environments. However, estimating speed at state scale for varying landscapes, environments, and road qualities has been relegated to manual engineering and expensive sensor networks. This thesis proposes an automated approach for estimating free-flow …

Algorithms For Achieving Fault-Tolerance And Ensuring Security In Cloud Computing Systems, Md. Tariqul Islam

Theses and Dissertations--Computer Science

Security and fault tolerance are the two major areas in cloud computing systems that need careful attention for its widespread deployment. Unlike supercomputers, cloud clusters are mostly built on low cost, unreliable, commodity hardware. Therefore, large-scale cloud systems often suffer from performance degradation, service outages, and sometimes node and application failures. On the other hand, the multi-tenant shared architecture, dynamism, heterogeneity, and openness of cloud computing make it susceptible to various security threats and vulnerabilities. In this dissertation, we analyze these problems and propose algorithms for achieving fault tolerance and ensuring security in cloud computing systems.

First, we perform a …

A Comparative Analysis Of Reinforcement Learning Applied To Task-Space Reaching With A Robotic Manipulator With And Without Gravity Compensation, Jonathan Fugal

Theses and Dissertations--Electrical and Computer Engineering

Advances in computing power in recent years have facilitated developments in autonomous robotic systems. These robotic systems can be used in prosthetic limbs, wearhouse packaging and sorting, assembly line production, as well as many other applications. Designing these autonomous systems typically requires robotic system and world models (for classical control based strategies) or time consuming and computationally expensive training (for learning based strategies). Often these requirements are difficult to fulfill. There are ways to combine classical control and learning based strategies that can mitigate both requirements. One of these ways is to use a gravity compensated torque control with reinforcement …

Nanostructured Device Designs For Enhanced Performance In Cds/Cu2S Heterojunction Solar Cells, Benjamin Wells

Theses and Dissertations--Electrical and Computer Engineering

Nanostructured CdS/Cu2S devices have been simulated using SCAPS-1D to demonstrate enhanced performance over traditional planar device structures. Two designs were examined: a nanowire CdS/planar Cu2S device and a nanowire CdS/nanowire Cu2S device. The addition of nanowires to a device had been previously demonstrated to improve device performance in a nanowire CdS/planar CdTe device by decreasing the amount of light absorbed by the CdS window layer, thus allowing more light to reach the absorber layer. Additionally, the total number of interface states can be greatly reduced due to the decreased total surface area between the window and absorber layers. The nanowire …

Investigation Of Host Nanotube Parameters For Enhancing The Performance Of Nanostructured Cds-Cdte Solar Cells, Deepak Kumar

Theses and Dissertations--Electrical and Computer Engineering

Numerical simulations are performed to investigate the effects of host nanotube parameters (pore diameter and pitch for different CdS coverages) and CdTe doping density on device performance in nanowire CdS/ CdTe solar cells using SCAPS-1D. This research finds the optimum values for these parameters in order to achieve the highest efficiency. Experimentally the effect of anodization voltage and fluoride ion concentration on the pore diameter and the pitch are studied for the Titania nanotubes host. It is observed that in the range of 0.3 mL to 2 mL of ammonium fluoride content, pore diameter and the pitch of the Titania …

Rapid Prototyping Of Nanostructures With Electron Beam Induced Processing, Samaneh Esfandiarpour

Theses and Dissertations--Electrical and Computer Engineering

Focused electron beam induced processing (FEBIP) is a nano-scale fabrication technique that allows the direct deposition of functional materials. However, it suffers from significant drawbacks, such as high cost, low speed, unavailable precursors for many materials and low purity of deposits. Liquid-phase focused electron beam induced processes (LP-FEBIP) are being investigated due to the potential benefits over the gas phase technique. In this method, deposition or etching occurs at the interface between a substrate and a bulk liquid. In this work, electron beam induced deposition of copper nanostructures from aqueous solutions of copper sulfate is demonstrated. The addition of sulfuric …

End-To-End Prediction Of Weld Penetration In Real Time Based On Deep Learning, Wenhua Jiao

Theses and Dissertations--Electrical and Computer Engineering

Welding is an important joining technique that has been automated/robotized. In automated/robotic welding applications, however, the parameters are preset and are not adaptively adjusted to overcome unpredicted disturbances, which cause these applications to not be able to meet the standards from welding/manufacturing industry in terms of quality, efficiency, and individuality. Combining information sensing and processing with traditional welding techniques is a significant step toward revolutionizing the welding industry. In practical welding, the weld penetration as measured by the back-side bead width is a critical factor when determining the integrity of the weld produced. However, the back-side bead width is difficult …

Resource Efficient Design Of Quantum Circuits For Cryptanalysis And Scientific Computing Applications, Edgard Munoz-Coreas

Theses and Dissertations--Electrical and Computer Engineering

Quantum computers offer the potential to extend our abilities to tackle computational problems in fields such as number theory, encryption, search and scientific computation. Up to a superpolynomial speedup has been reported for quantum algorithms in these areas. Motivated by the promise of faster computations, the development of quantum machines has caught the attention of both academics and industry researchers. Quantum machines are now at sizes where implementations of quantum algorithms or their components are now becoming possible. In order to implement quantum algorithms on quantum machines, resource efficient circuits and functional blocks must be designed. In this work, we …

Integration Of Large Pv Power Plants And Batteries In The Electric Power System, Oluwaseun M. Akeyo

Theses and Dissertations--Electrical and Computer Engineering

The declining cost of renewables, the need for cleaner sources of energy, and environmental protection policies have led to the growing penetration of inverter-based resources such as solar photovoltaics (PV), wind, and battery energy storage systems (BESS) into the electric power system. The intermittent nature of these resources poses multiple challenges to the power grid and substantial changes in the conventional generation and electrical power delivery practices will be required to accommodate the large penetration of these renewable power plants. The impact of large solar PV penetration on both generation and transmission systems, and the use of BESS to mitigate …

Articulatory-Wavenet: Deep Autoregressive Model For Acoustic-To-Articulatory Inversion, Narjes Alsadat Agha Seyed Mirza Bozorg

Theses and Dissertations--Electrical and Computer Engineering

Acoustic-to-Articulatory Inversion, the estimation of articulatory kinematics from speech, is an important problem which has received significant attention in recent years. Estimated articulatory movements from such models can be used for many applications, including speech synthesis, automatic speech recognition, and facial kinematics for talking-head animation devices. Knowledge about the position of the articulators can also be extremely useful in speech therapy systems and Computer-Aided Language Learning (CALL) and Computer-Aided Pronunciation Training (CAPT) systems for second language learners. Acoustic-to-Articulatory Inversion is a challenging problem due to the complexity of articulation patterns and significant inter-speaker differences. This is even more challenging when …

Selective Electron Beam Etching Of Materials Using Liquid Reactants, Sarah Lami

Theses and Dissertations--Electrical and Computer Engineering

Selective Electron Beam Etching of Materials Using Liquid Reactants Nanoscience and nanotechnology require advances in processing, patterning, and characterization of materials to overcome current limitations and generate new de-vices. Electron and ion beam-based processes are vital for fabrication and nano-scale prototyping with significant applications in nanoscale electronic, photonic, and magnetic devices; integrated circuit debugging; and lithographic mask and imprint template repair.

Focused ion and electron beams are routinely used to locally add (printing) or sub-tract (machining) materials. This type of material processing is becoming increasingly important to the integrated circuit manufacturing industry for editing and debug applications. Most significantly, as …

Bimetallic Nanoparticles Integrated Membranes For Groundwater Remediation: Synthesis, Characterization And Applications, Hongyi Wan

Theses and Dissertations--Chemical and Materials Engineering

The detoxification of chlorinated organics from groundwater, such as trichloroethylene (TCE), tetrachloroethylene (PCE), polychlorinated biphenyl (PCB) and carbon tetrachloride (CTC), is a challenging area. Reductive dechlorination has been investigated using iron and iron-based nanoparticles, such as bare Fe, sulfidized Fe (S-Fe) and palladized Fe (Pd-Fe). However, issues including particle agglomeration, difficulties in recycling and particle leaching have been reported to hinder the application and wide usage of these techniques. The integration of nanoparticles and membranes can address these issues because of the large surface area, stability, and the potential for versatile functionalities. In this study, commercial polyvinylidene difluoride (PVDF) microfiltration …

Characterization And Electrochemical Performance Of Dopamine-Sensitized Titania Thin Films, Joshua Garay

Theses and Dissertations--Chemical and Materials Engineering

Sensitization of mesoporous titania films with dopamine and polydopamine for visible light photoelectrochemical activity is investigated. Sensitization effectiveness is compared with 8 mM dopamine solutions of varying pH (acidic, basic, and neutral), as well as with a basic polydopamine solution. Vibrational changes due to dopamine attachment are determined from detached powders by Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) is used to quantify organics attached. X-ray photoelectron spectroscopy (XPS) of intact films probes the chemically induced charge shift from dopamine attachment. Cyclic voltammetry identifies the irreversible dopamine oxidation and tin reduction voltages. Finally, chronoamperometric curves are used to compare …

Effect Of Silica Nanoconfinement Of Lipid Bilayers On Its Phase Transition And On The Colloidal Stability Of Silica Nanoparticles, Aniruddha Atul Shirodkar

Theses and Dissertations--Chemical and Materials Engineering

In this work, we incorporated 4-(N-Boc-aminometyl) phenylboronic acid (BA), at different concentrations, into 1,2-dipalmitoyl-sn-glycero-3- phosphocholine (DPPC) bilayers confined within nanopores of two different mean pore diameters of 7.4 nm and 11.7 nm of micron sized silica particles. The confinement of DPPC into nanopores resulted in the depression in the main phase transition temperatures compared to the liposomal system. The addition of BA was found to induce disruptions in the acyl chains of the lipid molecules at all concentrations of the solute. The lipid bilayer cooperativity was found to be higher in the confined systems compared to the liposomal systems despite …