Engineering Commons^™

Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt

All Dissertations

With a cumulative generation capacity of over 100 GW, Photovoltaics (PV) technology is uniquely poised to become increasingly popular in the coming decades. Although, several breakthroughs have propelled PV technology, it accounts for only less than 1% of the energy produced worldwide. This aspect of the PV technology is primarily due to the somewhat high cost per watt, which is dependent on the efficiency of the PV cells as well as the cost of manufacturing and installing them. Currently, the efficiency of the PV conversion process is limited to about 25% for commercial terrestrial cells; improving this efficiency can increase …

Steps Toward A Net-Zero Campus With Renewable Energy Resources, Andrew Clarke

All Dissertations

With the increasing attention and support behind plug in hybrid electric vehicles, research must be conducted to examine the impacts of vehicles on electric distribution and transmission systems. This research aims first to model the behavior of vehicle battery chargers during system disturbances and mitigate any impacts. A distribution test system example is modeled and several different vehicle charger topologies are added. Faults are applied to the distribution system with vehicle chargers connected and the results are examined. Based on these results, a control strategy to mitigate their negative impacts is suggested. Photovoltaic panels are then added to the system …

Autonomous Control And Automotive Simulator Based Driver Training Methodologies For Vehicle Run-Off-Road And Recovery Events, Paul Freeman

All Dissertations

Traffic fatalities and injuries continue to demand the attention of researchers and governments across the world as they remain significant factors in public health and safety. Enhanced legislature along with vehicle and roadway technology has helped to reduce the impact of traffic crashes in many scenarios. However, one specifically troublesome area of traffic safety, which persists, is run-off-road (ROR) where a vehicle's wheels leave the paved portion of the roadway and begin traveling on the shoulder or side of the road. Large percentages of fatal and injury traffic crashes are attributable to ROR. One of the most critical reasons why …

The Development And Characterization Of Tannic Acid Cross-Linked Collagen Scaffolds For The Prevention Of Breast Cancer Recurrence In Lumpectomy Patients, Beau Inskeep

All Dissertations

Breast cancer is the second most common cancer amongst women, second only to lung cancer. In 2014, it was estimated that there were approximately 295,000 new cases of breast cancer diagnosed in women, with approximately 40,000 deaths caused by breast cancer in the United States. It has been reported that a woman has a 12% chance of developing breast cancer in her lifetime and a 3% chance of dying from breast cancer. There are several treatment options available for breast cancer, including chemotherapy, radiation therapy, as well as two different forms of surgery, mastectomy and lumpectomy. However, none of these …

Thermo-Mechanical Characterization Of Glass And Its Effect On Predictions Of Stress State, Birefringence And Fracture In Precision Glass Molded Lenses, Dhananjay Joshi

All Dissertations

The Precision Glass Molding (PGM) process was established as an economical and sustainable option for the production of aspherical glass optics to satisfy the increased industrial demand. Applications of precision molded aspherical lenses range from consumer electronics products such as cell phone cameras to defense and medical systems. An aspherical lens can eliminate the spherical and optical aberrations as compared to a spherical lens thus making the lens system more compact and lighter. In spite of being a clean and environmentally friendly process, the lens molding operation suffers from a few drawbacks such as lens profile deviation, stress birefringence/refractive index …

Robust Geotechnical Design - Methodology And Applications, Lei Wang

All Dissertations

This dissertation is aimed at developing a novel robust geotechnical design methodology and demonstrating this methodology for the design of geotechnical systems. The goal of a robust design is to make the response of a system insensitive to, or robust against, the variation of uncertain geotechnical parameters (termed noise factors in the context of robust design) by carefully adjusting design parameters (those that can be controlled by the designer such as geometry of the design). Through an extensive investigation, a robust geotechnical design methodology that considers explicitly safety, robustness, and cost is developed. Various robustness measures are considered in this …

Effects Of Transportation Hazards On Package Performance And Food Product Shelf Life, Kyle Dunno

All Dissertations

This research studied the effect of transportation hazards on food product shelf life and package performance. Studies were conducted to determine the effect of package headspace volume, product viscosity and storage temperature on package integrity. Finally, accelerated shelf life testing (ASLT) was utilized to determine how simulated transportation hazards affected the shelf life of a specific food product. Institutional retort pouches containing either water or 5% starch solution were filled with varying amounts of headspace volume to determine if package headspace volume could aid in package performance during simulated engineering tests for packaged products. Fixed displacement vibration testing and compression …

Estimating Field At-Rest Lateral Stress Coefficient And Liquefaction Resistance Of Aged Sands, Md Hossian

All Dissertations

Published results of laboratory tests to evaluate the influence of the at-rest lateral stress coefficient (K0) and the overconsoildation ratio (OCR) on liquefaction resistance of sands are reviewed in this dissertation. It is found that significant increase in liquefaction resistance can occur with high K0 and/or high OCR. A unique relationship between liquefaction resistance of isotropic and anisotropic normally consolidated sands exists based on the published laboratory data. Relationships between liquefaction resistance of overconsolidated sands and normally consolidated sands also have been shown in previous laboratory studies. Based on the previous studies, expressions for K0 and OCR correction factors (KK0 …

Robust Design Of Shield Tunnels ‒ Considering The Longitudinal Variation Of Input Parameters, Wenping Gong

All Dissertations

This dissertation, aimed at developing an improved design methodology for shield tunnels that explicitly considers design robustness against longitudinal variation of input parameters (such as soil parameters). To this end, a new solution model for shield tunnel performance analysis was first developed. In this new model, the random field concept was employed to model the longitudinal variation of input parameters. The input parameters (in the longitudinal domain) that had been generated with Monte Carlo simulation (MCS) were used as inputs for the tunnel longitudinal behavior analysis. Here, the finite element method (FEM) based upon Winkler elastic foundation theory was employed. …

Nonequilibrium Transport Of Ionic Liquids In Electrified Nanosystems, Xikai Jiang

All Dissertations

Room-temperature ionic liquids (RTILs) are a promising class of electrolyte that are composed entirely of ions but are liquid at room temperature. Their remarkable properties such as wide electrochemical window make them ideal electrolytes in many electrochemical systems. Because the non-equilibrium transport of RTILs often determines the performance of these systems, a fundamental understanding of such transport is needed. Here, using molecular dynamic (MD) and continuum simulations, we investigated the non-equilibrium transport of RTILs in three scenarios relevant to the application of RTILs in electrochemical systems: the electroosmotic flow (EOF) of RTILs through nanochannels, the electrokinetic transport of RTILs through …

Particle Scavenging By Water Drops In An Ultrasonic Standing Wave Field, Weiyu Ran

All Dissertations

Currently the backbone of the world's energy supply is composed of fossil fuels. However, the combustion of fossil fuels results in the production of enormous quantities of particulate pollutants. The smog resulting from these particulate pollutants causes significant health problem for city dwellers. Wet scrubbers, which use a water spray to scavenge airborne particles, is one of the most widely used devices to control particulate pollutants. Typical wet scrubbers can scavenge particles with diameters bigger than 10 um, but it is inefficient in scavenging particles with diameters on the order of 1 um. Unfortunately these fine particles are more dangerous …

High Frequency Devices And Circuit Modules For Biochemical Microsystems, Jiwei Sun

All Dissertations

This dissertation investigates high frequency devices and circuit modules for biochemical microsystems. These modules are designed towards replacing external bulky laboratory instruments and integrating with biochemical microsystems to generate and analyze signals in frequency and time domain. The first is a charge pump circuit with modified triple well diodes, which is used as an on-chip power supply. The second is an on-chip pulse generation circuit to generate high voltage short pulses. It includes a pulse-forming-line (PFL) based pulse generation circuit, a Marx generator and a Blumlein generator. The third is a six-port circuit based on four quadrature hybrids with 2.0~6.0 …

A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid

All Dissertations

This dissertation presents a novel comprehensive assessment methodology for using on-board photovoltaic (PV) solar technologies in vehicle applications. A well-to-wheels life cycle analysis based on a unique energy, greenhouse gas (GHG) emission, and economic perspective is carried out in the context of meeting corporate average fuel economy (CAFE) standards through 2025 along with providing an alternative energy path for the purpose of sustainable transportation. The study includes 14 different vehicles, 3 different travel patterns, in 12 U.S. states and 16 nations using 19 different cost analysis scenarios for determining the challenges and benefits of using on-board photovoltaic (PV) solar technologies …

Thermally Responsive Polymer Electrolytes For Inherently Safe Electrochemical Energy Storage, Jesse Kelly

All Dissertations

Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in …

Development Of An In Vitro Three-Dimensional Breast Tissue Model To Decipher The Effects Of Stromal Heterogeneity On Normal And Cancerous Mammary Epithelial Cells, Erin Mccave

All Dissertations

A goal of breast cancer research is to develop a detailed understanding of the underlying mechanisms of disease progression and to generate approaches to improve early detection, monitoring, and treatment of breast cancerous lesions. Current breast cancer therapies are not successful for all cases as they were developed as a standard of care for 'average' breast cancer condition. To further current clinical success, the characteristics of each tumor mass must be considered. Such an individualized or personalized approach is incompatible with current understanding of 'average' breast cancer tumors and responses to treatments. The long-term objective of the present research is …

Modeling Sustainability In Renewable Energy Supply Chain Systems, Fei Xie

All Dissertations

This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate 'environmental thinking' into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain …

Development Of A Transport System For Advancing Tissue Engineering And Cell Identification, Suzanne Mae Tabbaa

All Dissertations

This work centers on the development of a novel passive transport system for two tissue engineering applications – cell distribution and cell separation. This approach relies on a wicking fiber-based system, derived from the textile field that functions by directing and maintaining transport of cells as well as fluids and biomolecules. This system has the ability to enhance cell movement for both the purpose of cell seeding distribution as well as to isolate specific cell types from heterogeneous cell populations.

The success of spinal fusions and large bone defects is often limited by the decreased surrounding vasculature and the ability …

An Integrated Systems Engineering Methodology For Design Of Vehicle Handling Dynamics, Mandar Hazare

All Dissertations

The primary objective of this research is to develop an integrated system engineering methodology for the conceptual design of vehicle handling dynamics early on in the product development process. A systems engineering-based simulation framework is developed that connects subjective, customer-relevant handling expectations and manufacturers' brand attributes to higher-level objective vehicle engineering targets and consequently breaks these targets down into subsystem-level requirements and component-level design specifications. Such an integrated systems engineering approach will guide the engineering development process and provide insight into the compromises involved in the vehicle-handling layout, ultimately saving product development time and costs and helping to achieve a …

Investigation Of Subgrid-Scale Mixing In Turbulent Plane Jets And Turbulent Jet Flames, Shuaishuai Liu

All Dissertations

The subgrid-scale (SGS) mixing of mixture fraction, temperature, and species mass fraction in turbulent partially premixed (Sandia) flames is studied. We focus on the effects of the SGS mixing regimes and the spatial relationships among the scalars on the SGS mixing of the species mass fractions. High resolution lines images are used to obtain the scalar filtered mass density function and the conditionally filtered diffusion. The results show that for small SGS variance the scalar fields have a relatively simple structure. For large SGS variance the structure is more complex. The spatial relationships among the scalars result in different SGS …

Elastically Mismatched Interfaces As Related To Glass-To-Metal Seals, William Horton

All Dissertations

The mechanical performance of Glass-to-Metal seals is largely dependent upon the morphology of the oxide interfaces. The interfaces of the glass-to-metal region are transition zones consisting of a metallically bonded base metal with its reduced oxide and progress to interatomic bonds which are a mixture of ionic and covalent in a glass or ceramic base material. Differences in coefficient of thermal expansion, interatomic bonding and overall physical chemistry cause a number of issues in design, manufacture and lifetime serviceability of a G/M seal. To date the primary dimensions of interface assessment are microscopy and analytical chemistry. The purpose of this …

The Effects Of Secondary Trapping Mechanisms On Geologic Storage Of Carbon Dioxide, Catherine Ruprecht

All Dissertations

The goal of this Dissertation is to further the understanding of secondary trapping mechanisms in geologic CO₂ storage systems to improve storage design and security. This Dissertation takes the form of three chapters. The objective of the first chapter was to analyze the storage performance of supercritical and brine saturated CO₂ injection strategies to determine their advantages and disadvantages on distribution and immobilization of CO₂ and pressure buildup. Results showed dissolved CO₂ injection was favorable in terms of storage security in all cases as it resulted in smaller areal extents on the caprock and did not …

Composite Films With Magnetic Nanorods: Fundamentals, Processing And Applications, Yu Gu

All Dissertations

This Dissertation is centered on studying the composite films with magnetic nanorods. In recent years, one-dimensional magnetic nanostructures, such as magnetic nanorods, chains of magnetic nanoparticles, and nanotubes filled with magnetic nanoparticles have caught great attentions due to the breadth of applications. Their unique magnetic and geometrical features open new avenues of studies in medicine, sensors, optofluidics, magnetic swimming, and microrheology. In particular, they offered great opportunities for design of multifunctional devices and for manufacturing of anisotropic nano- and microstructures with unprecedented magnetic and mechanical properties. However, the strategy for nanorod alignment in both Newtonian and complex fluids has not …

Studies Of Imbalance Difference Theory In Modeling Conversion Between Differential Mode And Common Mode Signals, Li Niu

All Dissertations

This dissertation describes three related studies regarding the imbalance difference theory in modeling the conversion between differential mode and common mode/antenna mode signals. The topics covered are: rigorous derivation of imbalance difference theory for modeling radiated emission problems, modeling the conversion between differential mode and common mode propagation in transmission lines, and modeling the loading impedance on differential mode signals due to radiated emissions. The imbalance difference theory describes a method for calculating the coupling between differential mode signals and common mode signals due to changes in electrical balance on a transmission line. It provides both physical insight and a …

Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson

All Dissertations

Colloid-facilitated transport of the actinides has been observed previously in the field on the kilometer scale. The objective of this work is to investigate the mechanisms of colloid-facilitated transport with controlled settings and conditions. The experimental work in this dissertation investigates transport of a ternary complex with iron oxide colloids, organic ligands and actinides in the presence of quartz or a natural sandy soil as well as simplified systems building up to the ternary complexes. The first three papers investigate the following: (1) unsaturated transport of iron oxide colloids in a natural sandy soil lysimeter with and without natural organic …

Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes

All Dissertations

The environmental fate of actinides is greatly influenced by interfacial reactions, including sorption onto solid surfaces. Because changes in the primary hydration sphere of the actinide are expected to greatly influence the thermodynamics (i.e., reaction enthalpy and entropy) of these reactions, examining actinide sorption thermodynamics may provide insight into actinide sorption mechanisms. Additionally, examining actinide sorption thermodynamics may enhance the ability to model or predict these reactions in environmental or engineered systems where variable or elevated temperatures are expected. However, few researchers have studied actinide sorption thermodynamics. Therefore, this research examined the thermodynamics of Eu(III) (a trivalent actinide analog), Th(IV), …

Georgia's Water Policymaking Process And The Role Of Public Participation: Development And Analysis Of A Water Planning Process Evaluation Framework, Anna Eskridge

All Dissertations

This study analyzes the public's role in the regional water planning process that took place in the State of Georgia from 2009 to 2011. Specifically, this dissertation analyzes the extent to which a 'consensus-based' water planning process occurred by 1) examining the public participation plans that governed how the public was to contribute to the plan and policy formation, and 2) analyzing the public comments that were submitted at public meetings and commenting periods. By examining the participation plans and public comments, this study revealed the institutional, policy, legislative, and planning structures that influenced public participation in the regional water …

Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani

All Dissertations

The work in this dissertation is devoted to the synthesis and characterization of novel materials for off-line unattended sensing: shape-memory grafted nanofoams. The fabrication process and characterization of highly efficient, polymeric nanosensor element with the ability to selectively detect analytes and retain memory of specific exposure events is reported. These shape memory nanofoams could potentially act as efficient and highly sensitive coatings for evanescent waveguide-based optical monitoring systems. On exposure to specific analytes, the polymeric coatings locally change their internal structure irreversibly at the nanolevel, affecting the local optical properties such as refractive index. Currently, enrichment polymer layers (EPLs) are …

High-Productivity Membrane Adsorbers: Polymer Surface-Modification Studies For Ion-Exchange And Affinity Bioseparations, Heather Chenette

All Dissertations

This Dissertation centers on the surface-modification of macroporous membranes to make them selective adsorbers for different proteins, and the analysis of the performance of these membranes relative to existing technology. Traditional chromatographic separations for the isolation and purification of proteins implement a column packed with resin beads or gel media that contain specific binding ligands on their exposed surface area. The productivity of this process is balanced by the effective use of the binding sites within the column and the speed at which the separation can take place, in addition to the need to maintain sufficient protein purity and bioactivity. …

Unified Dynamics And Control Of A Robot Manipulator Mounted On A Vtol Aircraft Platform, Peng Xu

All Dissertations

An innovative type of mobile manipulator, designated Manipulator on VTOL (Vertical Take-Off and Landing) Aircraft (MOVA), is proposed as a potential candidate for autonomous execution of field work in less-structured indoor and outdoor environments. Practical use of the MOVA system requires a unified controller that addresses the coupled and complex dynamics of the composite system; especially the interaction of the robotic manipulator with the aircraft airframe. Model-based controller design methods require explicit dynamics models of the MOVA system. Preliminary investigation of a two-dimensional MOVA system toward a dynamics model and controller design is presented in preparation for developing the controller …

Microfluidic Particle And Cell Manipulation Using Reservoir-Based Dielectrophoresis, Saurin Patel

All Dissertations

Controlled manipulation of synthetic particles and biological cells from a complex mixture is important to a wide range of applications in biology, environmental monitoring, and pharmaceutical industry. In the past two decades microfluidics has evolved to be a very useful tool for particle and cell manipulations in miniaturized devices. A variety of force fields have been demonstrated to control particle and cell motions in microfluidic devices, among which electrokinetic techniques are most often used. However, to date, studies of electrokinetic transport phenomena have been primarily confined within the area of microchannels. Very few works have addressed the electrokinetic particle motion …