Engineering Commons^™

Underwater Cave Mapping And Reconstruction Using Stereo Vision, Nicholas Weidner

Theses and Dissertations

This work presents a systematic approach for 3-D mapping and reconstruction of underwater caves. Exploration of underwater caves is very important for furthering our understanding of hydrogeology, managing efficiently water resources, and advancing our knowledge in marine archaeology. Underwater cave exploration by human divers however, is a tedious, labor intensive, extremely dangerous operation, and requires highly skilled people. As such, it is an excellent fit for robotic technology. The proposed solution employs a stereo camera and a video-light. The approach utilizes the intersection of the cone of video-light with the cave boundaries resulting in the construction of a wire frame …

Development Of Novel Catalysts For Air Pollution Control, Chao Wang

Theses and Dissertations

The development of economy strongly related with increased consumption of fossil fuels, which causes severe air pollution issue. With more and more strict environmental regulations implemented all over the world, robust and efficient emission control technologies need to be innovated and applied to overcome the pollution challenge. This dissertation focuses on utilizing heterogeneous catalysis to eliminate carbon monoxide (CO), hydrocarbons (CH_x) and nitric oxides (NO_x) emissions produced from fossil fuel combustion.

The first type of catalyst is Pd supported on Mn-Ce solid solution. It achieves 100% CO conversion at room temperature. The high activity is attributed …

Modeling Battery Performance Due To Volume Change In Porous Electrodes Due To Intercalation, Taylor R. Garrick

Theses and Dissertations

The demand for energy continues to increase as the economies of developing countries become more modern and show an increased need for a reliable energy infrastructure in order to meet the increased demand associated with a large and more mobile population. An increased demand puts a strain on all sectors, however it is specifically noticeable in the transportation sector where a significant portion of the fuel utilized for transportation comes from petroleum and other fossil fuels. Recently, using alternative forms of energy for transportation has become reality, and in turn, using electricity as a transportation fuel has gained significant momentum, …

High Quality Low Offcut 4h-Sic Epitaxy And Integrated Growth Of Epitaxial Graphene For Hybrid Graphene/Sic Devices, Anusha Balachandran

Theses and Dissertations

Power electronic semiconductor devices are critical components in next-generation power systems such as hybrid electric vehicles and smart grid power controls enabling reduction in system size, weight, and cost. Wide bandgap materials such as SiC, GaN, and diamond have been investigated to replace silicon, due to their superior material properties. Of these, 4H-SiC is considered the most viable candidate beyond 3kV due to its technological maturity, its wide band gap (3.23 eV), high breakdown field (4×106 V/cm), high thermal conductivity (5 W/cm/K) and, more importantly, its indirect bandgap.

The main contribution of my research relates to the development and investigating …

Theoretical Investigation Of The Catalytic Hydrodeoxygenation Of Levulinic Acid Over Ru (0001) Catalyst Surface, Osman Mamun

Theses and Dissertations

Due to the rapidly declining fossil fuel reserves and the onset of global climate change, the development of active, selective, and stable catalytic materials for the efficient production of biomass derived platform chemicals, i.e., levulinic acid (LA), succinic acid (SA), γ-valerolactone (GVL) etc., is receiving considerable attention in order to produce second generation biofuels and commodity chemicals. Though solid lignocellulosic biomass is significantly cheaper than petroleum; however, the available technology is the significant barrier for large scale utilization of biomass for the production of biofuels. The development of biomass conversion technology requires, 1) identification of potential biomass chemicals that can …

Atherosclerotic Plaque Adhesion Strength And Its Role In Plaque Rupture, Bilal Merei

Theses and Dissertations

Cardiovascular diseases are disorders affecting the blood vessels and the heart. According to the World Health Organization, cardiovascular diseases are one of the leading causes of death worldwide. They are responsible for over 17.1 million deaths per year worldwide, representing 31.5% of deaths 1, 2. Atherosclerosis, a chronic inflammatory disorder affecting large arteries, is the underlying cause of many cardiovascular diseases. Plaque rupture is a serious complication of advanced atherosclerosis, often leading to life-threatening clinical consequences such as myocardial infarction (heart attack) or stroke. 75% of newly developed myocardial infarction cases are caused by atherosclerotic plaque rupture. It affects approximately …

Improved N-Type 4h-Sic Epitaxial Layer Radiation Detectors And Noise Analysis Of Front-End Readout Electronics, Khai V. Nguyen

Theses and Dissertations

Schottky barrier radiation detectors were fabricated on n-type 4H-SiC epitaxial layers (12 – 50 μm) grown by hot wall CVD process on highly nitrogen doped 4H-SiC (0001) substrates with 4-8º off-cut towards the ̅ direction. Ni/4H-SiC Schottky barrier radiation detectors, a very low leakage current of 0.18 nA at 250 V bias, revealing low thermal noise, was observed in current-voltage (I-V) measurements. Using a thermionic emission model, junction properties such as barrier height of ≥1.10 eV and an ideality factor of ≤1.29 were determined. An effective carrier concentration of 1.03×1015 cm-3 was calculated by capacitance-voltage (C-V) measurement. Deep level transient …

Computational Wave Field Modeling Using Sequential Mapping Of Poly-Crepitus Green’S Function In Anisotropic Media, Sajan Shrestha

Theses and Dissertations

In this thesis, a meshless semi-analytical computational method is presented to compute the ultrasonic wave field in the generalized anisotropic material while understanding the physics of wave propagation in detail. To understand the wave-damage interaction in an anisotropic material, it is neither feasible nor cost-effective to perform multiple experiments in the laboratory. Hence, recently the computational nondestructive evaluation (CNDE) received much attention to performing the NDE experiments in a virtual environment. In this thesis, a fundamental framework is constructed to perform the CNDE experiment of a thick composite specimen in a Pulse-Echo (PE) mode. To achieve the target, the following …

Advancing Automated Methods For Microrna Profiling, Kia N. Zellars

Theses and Dissertations

The widespread influence of miRNAs in many biological processes and characteristic changes in expression profiles make them potential biomarkers for a range of diseases. With recent discoveries highlighting the enrichment of particular circulating miRNAs in plasma under pathological conditions, there has been a push for technological advances in miRNA profiling studies as a diagnostic tool. A standardized, automated, high-throughput method for miRNA isolation from human plasma samples was developed in this study. Samples were subject to full miRNome profiling utilizing RT-qPCR. These unique findings demonstrate that developing a distinct miRNA biomarker profile for heart failure patients is feasible and holds …

Instability In Nonequilibrium And Nonthermal Plasma Discharges, Rajib Mahamud

Theses and Dissertations

Microplasma, or plasma in micron scale interelectrode separation, is an effective way to attain nonthermal plasma operation at atmospheric and higher pressure. However, the small size causes the effect of other operating parameters to be crucial in stable operation and make the microplasma discharge system to be susceptible to instabilities. The two major instabilities that are commonly observed are the instability in the negative differential resistance (NDR) region and the Striations or the ionization waves. The physics and reaction kinetics of NDR instability for high pressure system is not well understood. This study pursues both experimental characterization and development of …

Progressive Failure Analysis Of Composite Materials Using The Puck Failure Criteria, Karan Kodagali

Theses and Dissertations

Fiber reinforced composites have been used in various engineering structures and applications especially in naval, automotive, aeronautical and sports industries. These composite materials generally exhibit brittle damage behavior. The anisotropy in the material and different kinds of failure mechanisms make it difficult to accurately characterize the behavior of composite materials. The present work aims to verify and apply the Puck Failure Criteria using the commercially available finite element package ABAQUS by writing a user-material subroutine in FORTRAN. The model is implemented with different post failure degradation schemes.

In the present work, the progressive failure on composite materials in analyzed using …

Modeling Of Tow Wrinkling In Automated Fiber Placement Based On Geometrical Considerations, Roudy Wehbe

Theses and Dissertations

Automated manufacturing of fiber reinforced composite structures via numerically controlled hardware yields parts with increased accuracy and repeatability as compared to hand-layup parts. Automated fiber placement (AFP) is one such process in which structures or parts are built by adding bands of prescribed number of tows or slit-tape with prescribed width using robotic machine heads over 3D surfaces following prescribed paths. Despite the improved accuracy, different types of defects or manufacturing features arise during fabrication. These defects can be due to geometrical features, materials, and process planning parameters and are detected in the form of wrinkling, tow twist, tow folding, …

Fiber Optic Guided Wave Sensors For Structural Health Monitoring, Erik Frankforter

Theses and Dissertations

Risks and costs associated with aging infrastructure have been mounting, presenting a clear need for innovative damage monitoring solutions. One of the more powerful damage monitoring approaches involves using ultrasonic guided waves which propagate through a structure and carry damage-related information to permanently bonded sensors. Ultrasonic fiber-optic sensors are one of the most promising technologies for this application: they are immune to electromagnetic interference, present no ignition hazard, and transmit their data over tens of kilometers. However, before they can be widely employed, several limitations need to be overcome: poor sensitivity, unidirectional sensing, and loss of ultrasonic functionality due to …

Ultra High-Speed Signaling And Return On Technology Investment (Roti) For The Electrical Interconnects Sector, Azniza Abd Aziz

Theses and Dissertations

Demand for smaller platform sizes with increasing bandwidth has driven crosstalk problems that prevent bus performance to scale with Moore’s Law. Several approaches to reduce crosstalk such as the use of shields, differential links, and equalizers have been rejected due to higher cost and power required to overcome the signal integrity impediments at Gigahertz data rates. Eigen-mode signaling based on modal decomposition techniques is the most recent method to mitigate crosstalk that can potentially satisfy the demand for higher data rates from modern technology industry.

The goal of this research is to allow maximum dense routing between packages on PCBs …

A Lebesgue Sampling Based Diagnosis And Prognosis Methodology With Application To Lithium-Ion Batteries, Wuzhao Yan

Theses and Dissertations

Fault diagnosis and prognosis (FDP) plays an important role in the modern complex industrial systems to maintain their reliability, safety, and availability. Diagnosis aims to monitor the fault state of the component or the system in real-time. Prognosis refers to the generation of long-term predictions that describe the evolution of a fault and the estimation of the remaining useful life (RUL) of a failing component or subsystem.

Traditional Riemann sampling-based FDP (RS-FDP) takes samples and executes algorithms in periodic time intervals and, in most cases, requires significant computational resources. This makes it difficult or even impossible to implement RS-FDP algorithms …

Numerical Analysis Of Phase Change, Heat Transfer And Fluid Flow Within Miniature Heat Pipes, Mehdi Famouri

Theses and Dissertations

Heat pipes with broad applications in thermal systems have the ability to provide effective heat transport with minimal losses in over reasonable distances due to their passive nature. Their exceptional flexibility, simple fabrication, and easy control, not to mention, all without any external pumping power make them especially attractive in electronics cooling. Heat pipe development is motivated to overcome the need to presumably manage thermal dissipation in progressively compressed and higher-density microelectronic components, while preserving the components temperatures to specification.

Computation of flow and heat transfer in a heat pipe is complicated by the strong coupling among the velocity, pressure …

Promotional Effect Of Molten Carbonates On Proton Conductivity And Oxygen Reduction Reaction – An Experimental And Computational Study, Xiaolei Xiong

Theses and Dissertations

Recent research of Solid oxide fuel cells (SOFCs) is aimed to lower the operating temperature to an intermediate temperature (IT) range of 500 to 700^oC, while maintaining a proper performance. This Ph.D. research project investigates the promotional effects of alkaline carbonate eutectics on the proton conductivity of proton conducting electrolytes and cathodic ORR reactivity in SOFCs by both experimental and computational methods. The ionic conductivity of the MC-BZY composite above 500^oC increases with the higher loading of MC. The sample exhibited nearly a factor of two higher conductivity in H₂-containing atmosphere than in air. …

Analysis And Design Of A Highly Compact Ellipse-Shaped Ultra-Wideband Bandpass Filter (Uwb-Bpf) With A Notched Band, Xuetan Liu

Theses and Dissertations

Since the Federal Communications Commission’s endorsement of the frequency band of 3.1 – 10.6 GHz in 2002 to be unlicensed for wireless communication applications, various ultra-wideband bandpass filters (UWB-BPFs) have been proposed and designed. Different UWB-BPF configurations were presented in the past years to meet the very strict UWB-BPF specifications in terms of ultra-band requirement, low return loss, high rejection in notched bands. However, most of the previous works are limited by large dimension size, complex geometry, and high production cost.

The major objective of this work is to design a highly compact, simple geometry, and low-cost UWB-BPF, which passes …

Reducing Model Selection Computational Cost By Metamodeling The Evidence, Ramin Madarshahian

Theses and Dissertations

Modeling is an abstraction of reality that lets a designer or engineer perform simulations with a “real” object or structure without testing it physically. However, the result of simulations is as good as their models. Selecting the best model among many candidates is another challenge.

Complex models could translate into more accurate predictions, but they also require larger computational effort. The Bayes factor is often used to compare different models considering the data and analyst’s experience. To obtain the Bayes factor, the Bayesian model evidence is calculated; however, calculating the Bayesian model evidence of computationally expensive models is not a …

Distributed Optimization Method For Intelligent Control Of Dc Microgrids, Yuanyuan Fan

Theses and Dissertations

Most of the distributed energy resources, loads and energy storage systems in a DC microgrid are equipped with power electronic converters. With the integration of advanced power electronics devices, a microgrid is able to utilize a broader range of technologies in its design and operation. A key feature of power electronic converter based systems is the ability to direct energy flow within a system with their coordinated operation. A system level control is needed for coordination where converters execute reference points dictated by a system-level control in order to achieve system level goals. System goals can be expressed as a …

Nondestructive Evaluation And Health Monitoring Of Adhesively Bonded Composite Structures, William Walker Roth

Theses and Dissertations

As the growth of fiber reinforced composite materials continues in many industries, structural designers will have to look to new methods of joining components. In order to take full advantage of composite materials, such as increased stiffness, decreased weight, tailored material properties and increased fatigue life, mechanical fasteners will need to be replaced by adhesive bonding or welding, when possible. Mechanical fasteners require the drilling of holes, which damages the laminate and becomes the source of further fatigue damage. Also, an increase in laminate thickness or inclusion of other features is required for the material to withstand the bearing stress …

A Comprehensive Evaluation Of Hybrid Wetting Configurations On Dropwise Condensation, Karim Khazal Egab

Theses and Dissertations

The heat transfer during condensation on a surface depends on the pattern design of the surface, which can highly influence hydrophobic/hydrophilic wettability. In this study hybrid pattern designs were studied. The relationship between the droplet dynamic and the hybrid pattern design can alter the drainage rates, droplet departure frequencies, and the condensation heat transfer rates. Therefore, two series of hybrid patterned surfaces have been designed, developed, and tested during condensation of water vapor on horizontal copper tubes, and compared to complete dropwise and complete filmwise condensation samples. This is to investigate the design that provides the maximum improvement in the …

Determination And Validation Of High-Pressure Equilibrium Adsorption Isotherms Via A Volumetric System, Hind Jihad Kadhim Shabbani

Theses and Dissertations

Adsorption equilibrium isotherms for N2, CO2, and CH4 on zeolite 13X were investigated at three different temperatures (25.5, 50.5 and 75.5 ̊ C) and a pressure range of (0-6.89475) MPa for CH4 and N2 and in the range of (0-4.82633) MPa for CO2 using built in volumetric apparatus. The results were validated using with a volumetric system (ASAP) at the same temperatures and a pressure up to (160-110) KPa respectively. The experimental results were correlated using three process Langmuir (TPLM). The correlated isotherms were then used to calculate the isosteric heat of adsorption for the three gases on 13X. The …

Stilbenes: Therapeutic Interventions Targeting Amyloid Β Protein Aggregation In Alzheimer’S Disease, Yiying Wang

Theses and Dissertations

Alzheimer’s disease (AD) is the most common form of dementia and accounts for 60-80 % of all dementia cases. In the United States, AD is ranked as the 6th leading cause of death and it is the only one among the top 10 that cannot be prevented, treated or even slowed. All FDA approved drugs focus on attenuating the symptoms for a limited time by regulating neurotransmitters without any intervention with the underlying disease process. A major player in the initiation and development of this debilitating disorder is the misfolding and subsequent aggregating of amyloid-β (Aβ) peptide. This aggregation process …

Statistical Mechanics Of Lipid-Liquid Crystal Systems: From Fundamentals To Sensing Applications, Donya Ohadi Kabir Maghsudlu

Theses and Dissertations

Understanding the thermodynamics of small systems has a well-established history. The non-intuitive behavior of the intensive properties of small systems comprised of less than a few hundred particles has important implications in many areas of engineering and materials science. Nevertheless, many open questions about the thermophysical properties of systems not in the thermodynamic limit remain unanswered. In the first part of this work, we explore the consequences of the coupling of two small subsystems that together make up a larger isolated system through the use of statistical mechanics and molecular dynamics simulations of Lennard-Jones particles in two dimensions. The results …

Pollutant Formation In Oxy-Coal Combustion, Nujhat Choudhury

Theses and Dissertations

With the increasing levels of carbon dioxide (CO2) in the atmosphere, researchers are driven to seek cleaner combustion techniques to burn coal for power generation. Oxy-coal combustion is a promising technique to cut down CO2 emissions. This technology requires the introduction of a pure oxygen (O2) stream and a recycled flue gas stream into the boiler instead of air. Flue gas stream generated from the system will be low in volume and highly concentrated in CO2. Thus, the capture and sequestration process will be facilitated. But, one of the concerns of adopting this technology is the altered chemistry of pollutants …

Characterization Of Subgrade Resilient Modulus For Mepdg And The Effects On Pavement Rutting, Md Mostaqur Rahman

Theses and Dissertations

In 2008, the American Association of State Highway and Transportation Officials (AASHTO) released a modified pavement design method (i.e., the Mechanistic Empirical Pavement Design Guide (MEPDG)) based on Long Term Pavement Performance (LTPP) data from all over the United States. The MEPDG default design parameters developed from the LTPP database are expected to be significantly different than those for South Carolina material, traffic and weather conditions, thus the default design parameters may not be accurate for South Carolina. Therefore, the new pavement design method should be calibrated for South Carolina conditions by performing MEPDG local calibration.

Different input variables should …

Multi-Axis Multi-Material Fused Filament Fabrication With Continuous Fiber Reinforcement, Wout De Backer

Theses and Dissertations

Additive Manufacturing (AM) has become a well-recognized method of manufacturing and has steadily become more accessible as it allows designers to prototype ideas, products and structures unconceivable with subtractive manufacturing techniques for both consumer grade and industrial grade applications. Commonly used thermoplastics for 3D printing have properties that may not be sufficient to comply with the application’s certification requirements, or their performance is less than desirable for aerospace and other high performance applications. Additionally, additively manufactured parts have reduced mechanical properties in the build direction of the print, and are generally weaker than their equivalent injection-molded parts. Furthermore, Computer Aided …

Confluence Of Density Currents Produced By Lock-Exchange, Hassan Ismail

Theses and Dissertations

Density currents represent a broad classification of flows driven by the force of gravity acting on a fluid with variable density. With examples of density currents including turbidity currents, sand storms, salt wedges in tidal rivers, and oil spills, a great deal of attention has been previously given to understanding the underlying mechanisms of such flows and implications of those flows on fluid, species, and sediment transport. Although documented confluences occur naturally in terrestrial and submarine settings,little attention has been given to understanding the confluence of two density currents.

This study furthers the state of knowledge on density current confluences …

Integrating Nano-Patterned Ferromagnetic And Ferroelectric Materials For Smart Tunable Microwave Applications, Tengxing Wang

Theses and Dissertations

The wireless communication market has been ever-growing in the recent decades. Radios with high performance and capabilities to support wireless connections are increasingly demanded. Recent developments in wireless communications targeting ubiquitous connections have resulted in ever more complex system structures for supporting multiple frequency bands and standards. Reconfigurable and tunable RF/microwave technologies have the potential to significantly simplify the systems. The main objective of this dissertation is to develop tunable technologies and design concepts, and propose a new design methodology to implement dually electrically tunable microwave components by integrating both selectively patterned ferromagnetic and ferroelectric materials.

The first part of …