Engineering Commons^™

Fundamental Understanding Of Plasma Discharge Formation In Liquid And Multiphase Configurations Through Multiphysics Modeling, Ali Charchi Aghdam

Theses and Dissertations

During the last two decades, non-thermal plasma discharges in and in contact with liquids have received significant attention due to their wide range of applications including chemical analysis, medical, water treatment, fuel processing, etc. Despite the tremendous interest and advances attained in the experimental studies, modeling efforts providing a comprehensive understanding of the underlying physicochemical processes are limited. There is still no unified theory on plasma formation in dense medium and various theories have been proposed such as the presence of bubbles and tunneling which are topics of debate. In the first part of this study, a mathematical model is …

Evaluation Of Temporal Damage Progression In Concrete Structures Affected By Asr Using Data-Driven Methods, Vafa Soltangharaei

Theses and Dissertations

Alkali-silica reaction (ASR) is a chemical reaction, which causes damage in concrete structures such as bridges, dams, and nuclear containments and powerplant structures. The ASR-induced damage may endanger the integrity and serviceability of structures. Several methods such as visual inspection, petrographic analysis, demountable mechanical strain gauges, and cracking index have been utilized for study the effect of ASR on structures, which are not always efficient in early damage detection and some are destructive and prohibited in nuclear structures. Nondestructive methods and structural health monitoring techniques can be alternatives for the condition assessment of structures. Among the nondestructive methods, acoustic emission …

On The Robustness Of Bayesian Network Learning Algorithms Against Malicious Attacks, Noah Joseph Geveke

Theses and Dissertations

Bayesian networks are effective tools for discovering relationships between variables in a data set. Algorithms that learn Bayesian networks from data fall into three categories: constraint-based, score-based, and hybrid. Hybrid algorithms contain a constraint testing sub-procedure as well as a score function to create the network. Malicious changes to the training set can cause invalid networks that do not model the true data. The effects of these changes have been demonstrated using the PC algorithm, a constraint-based algorithm. In this thesis a method was developed to measure the robustness of various algorithms to determine potential malicious changes. The robustness analysis …

Enhancing Single And Two-Phase Heat Transfer Of Microgap Heat Sinks Using Nano-Structure Coatings, Yueyang Zhao

Theses and Dissertations

Due to the shrinking size and increasing power of electronics, the heat flux generated by electronic devices has greatly increased and imposed challenges to thermal management technologies. Numerous cooling technologies have been developed to cool high-power electronics. Among them, flow boiling in microchannels or a microgap has been one of the most efficient ways to remove high heat flux, which requires less coolant compared with single-phase cooling techniques. However, the flow boiling instability is the one of the most challenging issues, which lead to the premature critical heat flux (CHF) conditions and deteriorate heat transfer rate. The capillary force generated …

Design Of High Efficiency Wireless Power Thansfer System With Nonlinear Resonator, Yibing Zhang

Theses and Dissertations

Wireless power transfer technology (WPT) has been rapidly developed in recent years. The primary benefit of WPT is that it replaces the traditional wire charging with a cordless charging method. WPT technology has been applied in many fields, such as bio-implants, electric vehicles, and wirelessly charging systems. According to the different energy transmission mechanism, WPT technology can be divided into magnetic field coupling (includes magnetically coupled inductive and magnetically-coupled resonant), microwave radiation, laser emission, electrical-field coupling, and ultrasonic transmission type. Among these technologies, the magnetic resonance coupling method has a better promise because of its long transfer distance and high …

Novel Multi-User Chirp Signaling Schemes For Future Aviation Communication Applications, Nozhan Hosseini

Theses and Dissertations

Many wireless communication systems will need to accommodate a larger number of users in the future. One application in particular in which this is critical is low data rate, long range communication links with very large numbers of nodes, such as the internet of things (IoT), possibly the internet of flying things (IoFT), etc. These systems demand advanced multi-access techniques with minimal multiple access interference (MAI). They should also be robust to multiple impairments, including multipath channel distortions, Doppler spreading, and interference. Chirp waveforms are one type of waveform set that can satisfy future system demands in the presence of …

Expansion Microscopy: A New Approach To Microscopic Evaluation, Ashley Ferri

Theses and Dissertations

Optical microscopy resolution is limited by the wavelengths of light and the series of microscope lenses and other optical components used to create a magnified image of cell structures in a sample. Often the cell structures are smaller or closer together than the resolution limits of a light microscope. In 2015 the Boyden group at the Massachusetts Institute of Technology (MIT) created a sample preparation technique, expansion microscopy which involves embedding biological samples in a crosslinked, swellable, hydrogel polymer that allows for uniform physical separation of cell components so that they can subsequently be resolved by light microscopy. Using the …

Fundamental Studies Of Oxygen Electrocatalysis In Alkaline Electrochemical Cells, Victoria F. Mattick

Theses and Dissertations

Until recently the world’s main source of energy has been fossil fuels, such as coal and petroleum. However, these energy sources are polluting our planet, becoming scarce and increasingly inaccessible, and are costly to extract. Therefore, much attention has been directed to harvesting clean, abundant, and renewable energy, such as solar rays and wind. However, the intermittency of solar and wind power generation requires an effective energy buffering solution (aka energy storage) to become efficient and reliable. With high efficiency and energy density, rechargeable batteries and reversible fuel cells are two of the best methods for this purpose. Unfortunately, a …

Investigation Of Oxidized Carbon Supported Au Catalysts Synthesized Via Strong Electrostatic Adsorption Of Au(En)2Cl3 For The Hydrochlorination Of Acetylene To Vinyl Chloride Monomer, Sean Reginald Noble

Theses and Dissertations

Over 20 million tons of vinyl chloride monomer (VCM) is produced every year using acetylene hydrochlorination using a supported mercuric chloride catalyst. During this process mercury is reduced and sublimes into the environment harming all living animals and humans, so carbon-supported Au catalysts have been developed in attempts to replace it. Various techniques have been used to make these catalysts including several variations of dry impregnation. In this study we investigate the ability of Strong Electrostatic Adsorption (SEA) of Au(en)₂Cl₃ onto various supports to demonstrate the ability to rationally and consistently synthesize gold catalysts with ultra-small particle …

Theoretical Investigation Of The Biomass Conversion On Transition Metal Surfaces Based On Density Functional Theory Calculations And Machine Learning, Wenqiang Yang

Theses and Dissertations

During the past decades, heterogenous catalyzed conversion of biomass to hydrocarbons with similar or identical properties to conventional fossil fuels has gained significantly academic and industrial interest. However, the conventional heterogeneous catalysts such as sulfided NiMo/Al₂O₃ and CoMo/Al₂O₃ used have various drawbacks, such as short catalyst lifetime and high sulfur content of product. To overcome the limitations of the conventional sulfided catalysts, new catalysts must be developed, which requires a better understanding of the reaction mechanism of the biomass conversion. Based on density functional theory, in this thesis, we reported a computational calculation study …

The Hybridization Of A Graphene And Silicon Carbide Schottky Optoelectronic Device By The Incorporation Of A Lead Sulfide Quantum Dot Film, Joshua Letton

Theses and Dissertations

The work that follows examines the impact of lead sulfide quantum dots on a native epitaxial graphene (EG) SiC Schottky device, resulting in a hybrid optoelectronic device which presents a possible avenue towards a novel hybrid carbide-based Schottky solar cell. The active (n-type SiC) and contact (graphene) layers for the Schottky junction of the device were grown epitaxially using a novel technique incorporating tetrafluorosilane (TFS) as a precursor gas. The bare EG/SiC device was characterized based on its I-V behavior in dark and under illumination for both forward and reverse bias conditions. The initial characterization demonstrated the expected Schottky diode …

Synthesis And Characterization Of Novel Silicone Hydrogel Biomaterials With Advanced Properties For Ocular Drug Delivery, Liana D. Wuchte

Theses and Dissertations

There is a need for next generation silicone hydrogel biomaterials with greater compositional flexibility and tailorable material properties for advanced manufacturing and new applications for ocular drug delivery. Poly(DMS-R11-co-TRIS-co-DMA-co-PEG200DMA-co-DEAEM-co-DADMAC) silicone hydrogel contact lenses were synthesized with macromolecular memory and showed 7-day in vitro release of latanoprost acid via a microfluidic platform with controlled release and improved drug payload capacity compared to control lenses. Six newly synthesized silicone macromers were then incorporated into contact lens formulations for the first time to produce a novel, improved platform. Various silicone macromer structures showed significantly improved solubility with TRIS and DMA with components ranging …

Novel Injectable Plga-Peg-Plga Self-Assembled Hydrogels For The Extended And Controlled Release Of Dna Nanocarriers To Prevent Secondary Cataracts, Laura L. Osorno

Theses and Dissertations

Cataracts are the second leading cause of blindness worldwide. There are over 20 million cataract surgeries each year, and these cases are expected to double within the next ten years. Over 40% of adults and nearly all children develop secondary cataracts, or posterior capsule opacification (PCO), following cataract surgery. Currently, Nd:YAG laser therapy is used to treat PCO; however, laser therapy is not available worldwide and treatment may have adverse effects on surrounding ocular tissues. Thus, there is a considerable unmet need for more efficacious and convenient treatments to prevent PCO.

Injectable, stimuli-responsive gels were designed using poly(lactic-co-glycolic acid)-b-poly(ethylene glycol)) …

Designing Silk Protein-Based Composite Materials With Tunable Heat Transfer And Magnetic Properties, Ye Xue

Theses and Dissertations

Renewable and biocompatible silk protein materials with desired physical properties show promising applications in biomedical field. In this work, a set of protein-based composites with desired thermal and magnetic properties, enhanced by the appropriate distribution of nanofillers in the protein matrix in both 2D-film and 1D-fiber forms was investigated. Results indicate that secondary structures of silk protein materials regenerated by a formic acid-calcium chloride method are different from those of their respective natural silk fibers. Intramolecular beta-sheet structures were found to dominate these silk films, causing these regenerated samples to be water-insoluble but more flexible than traditional silk films with …

Examining Global Perspectives Of Engineering Students: Determining Educational Impact, Brian R. Moore

Theses and Dissertations

Globalization is causing higher education to adapt their approaches to student learning, especially those in the engineering disciplines as the nature and impact of their work becomes more cross-cultural and diverse. The efforts of programmatic change have led universities to emphasize new or different student experiences and educational practices to better prepare graduates for this societal change. Given this trend, research on which educational practices have the most impact on preparing engineering graduates to enter a global workforce is needed. Research has shown that international experiences like study abroad have a positive impact on students' global perspectives, especially when they …

Polyimide/Silicon Dioxide Nanocomposites As Dielectrics For Helium-Cooled High-Temperature Superconducting Cables, Harrison Michael Hones

Theses and Dissertations

In this thesis, polyimide (PI) and silicon dioxide (SiO2) were combined in the form of a nanocomposite for use as a dielectric on helium-cooled high-temperature superconducting (HTS) cables. Further, a cryogenic chamber was designed with the intent of cooling samples to 40 K for dielectric and thermal contraction testing. Composites were created through an in situ process which resulted in nanoparticle formation within the host matrix. Samples were tested for dielectric strength at room temperature (300 K) as well as cryogenic temperature (92 K) using liquid nitrogen as the coolant. Composite samples tested at 300 K averaged a dielectric strength …

Bijels Made By Solvent Transfer Induced Phase Separation: Formation Principles And Transport, Stephen Boakye-Ansah

Theses and Dissertations

Bijels are made of non-equilibrium particle-stabilized emulsions with a bicontinuous arrangement of the constituent fluid phases. They spontaneously form through arrested spinodal decomposition in mixtures of partially miscible liquids and neutrally wetting colloidal particles. Soon after their discovery over 10 years ago, Prof. Mike Cates, Lucasian Professor of Mathematics, predicted their future use as continuously operated cross-flow reactors for chemical reactions between immiscible reactants.

Towards this goal, work in this thesis focuses on designing bijels via Solvent Transfer Induced Phase Separation (STrIPS) for microfluidic transport applications. Structure-function relationships of STrIPS bijels stabilized by silane functionalized nanoparticles are developed. In-situ surfactant …

Evaluating And Improving The Seu Reliability Of Artificial Neural Networks Implemented In Sram-Based Fpgas With Tmr, Brittany Michelle Wilson

Theses and Dissertations

Artificial neural networks (ANNs) are used in many types of computing applications. Traditionally, ANNs have been implemented in software, executing on CPUs and even GPUs, which capitalize on the parallelizable nature of ANNs. More recently, FPGAs have become a target platform for ANN implementations due to their relatively low cost, low power, and flexibility. Some safety-critical applications could benefit from ANNs, but these applications require a certain level of reliability. SRAM-based FPGAs are sensitive to single-event upsets (SEUs), which can lead to faults and errors in execution. However there are techniques that can mask such SEUs and thereby improve the …

Dynamic Reconfigurable Real-Time Video Processing Pipelines On Sram-Based Fpgas, Andrew Elbert Wilson

Theses and Dissertations

For applications such as live video processing, there is a high demand for high performance and low latency solutions. The configurable logic in FPGAs allows for custom hardware to be tailored to a specific video application. These FPGA designs require technical expertise and lengthy implementation times by vendor tools for each unique solution. This thesis presents a dynamically configurable topology as an FPGA overlay to deploy custom hardware processing pipelines during run-time by utilizing dynamic partial reconfiguration. Within the FPGA overlay, a configurable topology with a routable switch allows video streams to be copied and mixed to create complex data …

Development And Evaluation Of Dimensionally Adaptive Techniques For Improving Computational Efficiency Of Radiative Heat Transfer Calculations In Cylindrical Combustors, Todd Andrew Williams

Theses and Dissertations

Computational time to model radiative heat transfer in a cylindrical Pressurized Oxy-Coal (POC) combustor was reduced by incorporating the multi-dimensional characteristics of the combustion field. The Discrete Transfer Method (DTM) and the Discrete Ordinates Method (DOM) were modified to work with a computational mesh that transitions from 3D cells to axisymmetric and then 1D cells, also known as a dimensionally adaptive mesh. For the DTM, three methods were developed for selecting so-called transdimensional rays, the Single Unweighted Ray (SUR) technique, the Multiple Unweighted Ray (MUR) technique, and the Single Weighted Ray (SWR) technique. For the DOM, averaging methods for handling …

Thermal Conductivity And Diffusivity Measurement Assessment For Nuclear Materials Raman Thermometry For Uranium Dioxide And Needle Probe For Molten Salts, Peter Ward Hartvigsen

Theses and Dissertations

In the near future, Gen II, III, and IV nuclear reactors will be in operation. UO2 is a common fuel for reactors in each of these generations and molten salts are used as coolant/fuel in Gen IV molten salt reactors. This thesis investigates potential ways to measure thermal conductivity for these materials: Raman thermometry for UO2 and a needle probe for molten salts. Four Raman thermometry techniques are investigated in this thesis: The Two Laser Raman (TLR), Time Differential Domain Raman (TDDR), Frequency Resolved Raman (FRR), and Frequency Domain Raman (FDR). The TLR is a steady state method used with …

Evaluating Cracking Performance Of Polymer Enhanced And Fiber Reinforced Microsurface Mixtures Using Asphalt Laboratory Testing, George Joseph Shackil

Theses and Dissertations

This study presents a method to improve and evaluate the cracking resistance of microsurfacing mixtures using common asphalt laboratory testing. A preliminary optimal timing study and a study to evaluate improvements to cracking performance were conducted. The control mixture was based on NJDOT standard mix design specifications. Three mixtures were tested in this study: a fiber reinforced mixture using one-quarter inch glass fibers, an emulsion with increased SBR (polymer) contents, and a mixture using the one-quarter inch glass fibers combined with the increased polymer contents. Three laboratory tests were used to evaluate three different cracking resistance parameters: crack initiation (Semi-Circular …

Increasing The Manufacturing Readiness Of Refill Friction Stir Spot Welding, Brigham Ammon Larsen

Theses and Dissertations

Refill friction stir spot welding (RFSSW) is an emerging technology, capable of joining thin sheets of aluminum alloys. The present thesis comprises two studies which were conducted to address two challenges faced by RFSSW: the long cycle time traditionally associated with welding and the poor life of existing RFFSW tools. In the first study, welds were made in AA5052-H36, at various cycle times and with various process parameters. It was shown that RPM, cycle time, and material thickness, all have an effect on the machine response. Decreasing RPM or weld duration leads to increased force and torque response during welding. …

Lcm Permeability Characterization Over Mold Curvature, Benjamin Grant Betteridge

Theses and Dissertations

Composite flow simulation tools for LCM processing can be expensive and time-consuming but necessary to design a mold system with proper placement of resin inlets and vacuum outlets. Composites manufacturing engineers would benefit from data regarding the impact of mold curvature radius on resin flow. This could help determine whether or not a particular part and mold would require expensive simulation software designed to handle complex flow paths through curved fabric architectures exhibiting variable permeability over the curvature, or if simple flow modeling would provide accurate enough simulations for sound tooling setup decision making. Four molds, with double curvature having …

Observing The Impact Of An Engineering-Based Unit Of Instruction On 6th Grade Students' Attitudes Towards Engineering As Theyengage In Building Electric Bikes, Gregg Allred Olsen

Theses and Dissertations

In the past few decades, science, technology, engineering, and math (STEM) education has become a driving force for innovators throughout the world (Atkinson & Mayo, 2010; Bybee, 2010). STEM education has also become an economic factor in developing countries (Kennedy & Odell, 2014). Currently, many countries are struggling with how to effectively promote STEM education. The United States (U.S.) provides an interesting case study. Despite being one of the global economic leaders, it is behind in STEM education compared to other nations (Atkinson & Mayo, 2010; Dugger, 2010). STEM education helps to build world leaders including marketable and knowledgeable employees …

Creating Library Learning Spaces That Support Twenty-First Century Pedagogy And Student Learning, Deborah Lynn Christoffersen

Theses and Dissertations

University libraries struggle to keep up with rapidly changing technology and the associated change in teaching strategy. Most administrators and librarians are often not trained to assess space needs and struggle to reassign library spaces for non-traditional library use. As such, they often embark on expensive and time-consuming feasibility studies, using (typically) hard-earned monies to complete the research or to pilot a new space. What academic research library administrators and staff lack is an analysis tool for discovering and planning needed renovations and improvements in aging library facilities. The purpose of this research project was to determine how students use …

An Agent-Based Decision Support Framework For Suas Deployment In Small Infantry Units, Carsten Douglas Christensen

Theses and Dissertations

Small unmanned aircraft systems (sUAS) will become a disruptive force on the modern battlefield. In recent years, sUAS size and cost have decreased while their capability has increased. They have forced a reconsideration of the air superiority paradigm held since the First World War. Perhaps their most attractive, and worrisome, feature is the huge range of combat roles that they might fulfill. The presence of sUAS on future battlefields is certain, but the role they will play and their impact on those battlefields are not. This work presents a decision support framework for sUAS deployment in small infantry units. The …

Quantifying The Conditioning Period For Geogrid-Reinforced Aggregate Base Materials Through Cyclic Loading, Chad Derrick Vickery

Theses and Dissertations

Geogrid reinforcement can improve the performance of pavements by stiffening the aggregate base material and decreasing pavement deformations. Understanding the effects of cyclic loading on the modulus of geogrid-reinforced base materials would help engineers better anticipate actual increases in the modulus of aggregate base materials under given traffic loads. The objective of this laboratory research was to investigate the effects of cyclic loading on the resilient modulus, the modulus to peak axial stress, the elastic modulus, and the modulus at 2 percent strain of geogrid-reinforced aggregate base materials. The scope of the research included two aggregate base materials (Wells Draw …

Impacts Of Changing The Transit Signal Priority Requesting Threshold On Bus Performance And General Traffic: A Sensitivity Analysis, Michael Harmon Sheffield

Theses and Dissertations

A sensitivity analysis was performed on the transit signal priority (TSP) requesting threshold to evaluate its impact on bus performance and general traffic. Two distinct bus routes were evaluated to determine the optimal requesting threshold that would balance the positive impacts on bus performance with the negative impacts on general traffic. Route 217, a conventional bus route, and the Utah Valley Express (UVX), a bus rapid transit line, utilize a dedicated short-range communication (DSRC)-based TSP system as part of their normal, day-to-day operations. Using field-generated data exclusively, bus performance and general traffic were evaluated over a 7-month period from February …

A Systems-Level Approach To The Design, Evaluation, And Optimization Of Electrified Transportation Networks Using Agent-Based Modeling, Landon Clark Willey

Theses and Dissertations

Rising concerns related to the effects of traffic congestion have led to the search for alternative transportation solutions. Advances in battery technology have resulted in an increase of electric vehicles (EVs), which serve to reduce the impact of many of the negative consequences of congestion, including pollution and the cost of wasted fuel. Furthermore, the energy-efficiency and quiet operation of electric motors have made feasible concepts such as Urban Air Mobility (UAM), in which electric aircraft transport passengers in dense urban areas prone to severe traffic slowdowns. Electrified transportation may be the solution needed to combat urban gridlock, but many …