Engineering Commons^™

Pvdf Membranes With Stable, Ultrathin Graphene Oxide (Go) Functional Coatings For Antifouling Oil/Water Separation Under Cross-Flow Condition, Lei Wang

Theses and Dissertations

Oil/water separation plays an important role in industrial wastewater treatment and environment protection. For the treatment of oily wastewater, especially for removing oil droplets with sizes in the micrometer range, ultrafiltration (UF) membrane technology is considered the most efficient method due to its high separation efficiency and relatively simple operational process. However, caused by the deposition of the oil droplets onto the membrane surface and into the membrane pores, the fouling of UF membranes shortens their service time and degrades their separation performance in practical applications.

In this work, graphene oxide (GO) was utilized as a novel coating material to …

Enabling Studies To Optimize Biomaterials For The Treatment Of Myocardial Infarction, Eva Adriana Romito

Theses and Dissertations

The canonical mechanism of wound healing is disrupted following a myocardial infarction (MI), manifesting as an unregulated response that negatively impacts left ventricular (LV) function. This mechanism, termed post-MI remodeling, culminates in an outcome that favors progression to a systolic heart failure state and death for the patient. Therapeutic approaches following the occurrence of a MI are designed to modulate the natural remodeling process and mitigate the loss of cardiac function. The mechanics and structure of the healing infarct have been the focus of numerous pre-clinical and clinical investigations, leading to the impending clinical introduction of material injections as a …

Development Of Pressure Swing Adsorption (Psa) Processor Co2 Capture From Flue Gas, Md. Atikur Rahman

Theses and Dissertations

Reducing the anthropogenic CO2 emissions and lowering the concentration of greenhouse gases in the atmosphere has become one of the most important environmental issues of recent times. To this end, the development of a cost effective pressure swing adsorption (PSA) process, utilizing commercially available 13X zeolite as the adsorbent, is underway to remove and concentrate CO2 in the flue gas of a coal-fired power plant. This systematic development effort has been carried out so far at the bench scale. It has included the following studies that defined and validated this PSA process both experimentally and via a PSA process model. …

Ultra-High Temperature Full Field Deformation Measurements Of Materials Subjected To Thermo-Mechanical Loading: A Dic Based Study, Guillemo A. Valeri Paoli

Theses and Dissertations

Determining the mechanical response of materials at elevated temperatures is a subject of great interest in metal forming, aerospace and aero-engine industries. For example, measurement of the deformation response under tensile loading at high temperatures is crucial for establishing thermomechanical and thermo-physical properties of materials, consequently, determining the reliability of a component or structure exposed to elevated temperatures. In order to predict the behavior of materials at ultra-high temperatures, a novel experimental approach based on Digital Image Correlation (DIC) is proposed and successfully applied to different materials at temperatures ranging from room temperature to 1100˚C. In these studies, a portable …

Study Of Friction Extrusion And Consolidation, Xiao Li

Theses and Dissertations

Friction extrusion and consolidation was invented by The Welding Institute (Cambridge, UK) in the early 1990’s. It is related to simple extrusion processes with the primary difference being that the extrusion die rotates about the extrusion axis and the die is required to impart substantial deformation to the initially, finely divided charge (like metal waste or chips) in order to consolidate it prior to extrusion. It can produce high quality wire and fully consolidated bulk material from low-cost precursors like metal chips or powders. The advantages lie in that it is a direct method to recycle metal chips or scraps …

An Improved Ship Design Tool For Comparing Performance Of Multiple Ship Designs Across User-Defined Missions, Helder Jose De Almeida Pais

Theses and Dissertations

In the early stages of ship design, engineers from many different disciplines need to have confidence that a design being produced converges across the electrical, mechanical, and thermal domains, and that the design meets the needs of the stakeholders, and, that a particular design performs better or more optimally than other designs produced to accomplish a mission. The tools currently available do not permit the engineering teams to gain this insight in a reasonable amount of time. In this thesis, we discuss the improvements that we have made to our existing ship design tools in the S3D environment, allowing for …

Multiscale Modeling Of Water Transport And The Influence Of Water Quality Parameters On Membrane Processes, Linkel Kwabena Boateng

Theses and Dissertations

Membrane-based desalination processes have become a viable means of producing potable water to meet water resource needs in both industrialized and developing nations. Extensive experimental investigation, in conjunction with computational modeling is critical in the development of sustainable and cost-effective desalination technologies. The overall goal of this dissertation is to develop a multiscale modeling framework to elucidate water and salt transport mechanisms and the influence of water quality parameters on membrane processes. The key tasks involved in this study are: establish a criterion for estimating water flux using Bayesian inference; develop a multiscale framework to connect molecular dynamics (MD) simulations …

Comparative Analysis Of Current Control Methods For Modular Multilevel Converters, Jordan D. Rogers

Theses and Dissertations

Modular Multilevel Converters (MMCs) are power electronic converters comprised of a series connection of sub-modules. Their modular structure allows for the possibility to design high-voltage converters that are suitable for utility applications due to the modular fail-safe structure with reduced switching frequency requirements. Some areas of interesting research specific to the MMC topology include modulation techniques, control methods, capacitor voltage balancing strategies, and circulating current suppression control. This thesis presents the development of a predictive current control for MMCs that has the benefit of inherently reduced circulating currents within the converter’s phase units. Two other typical MMC current control strategies …

Characterization, Synthesis And Stabilization Of Au Based Bimetallic Catalysis For The Hydrochlorination Of Acetylene, Kerry Charles O'Connell

Theses and Dissertations

Polyvinyl chloride (PVC) is the third most-produced plastic polymer world-wide by volume after polypropylene and polyethylene. Vinyl chloride monomer, which is polymerized into PVC, is produced via mercuric chloride catalysts that deactivate as mercury sublimes into the atmosphere from the catalyst surface, resulting in substantial environmental concerns.

In an effort to rationally synthesize non-mercuric catalysts, strong electrostatic adsorption (SEA) was used to prepare highly dispersed and active gold nanoparticles over low point of zero charge (PZC) carbon to increase the active metal surface area. The use of <1.5nm gold clusters did not lead to large increases in activity as there was an increased degree of particle coalescence during reaction for activated carbon supported samples. A pronounced support effect was observed in which oxide supports completely prevented Au sintering, but was virtually inactive. This suggests that the active site for the hydrochlorination reaction involves the carbon surface.

The stabilization of carbon supported gold nanoparticles in the HCl-rich reaction environment was …

Time-Domain Measurement Of Ultrafast Magnetization Dynamics In Magnetic Nanoparticles, Brian Egenriether

Theses and Dissertations

Ultrafast time-domain measurements are made on collections of Fe3O4 magnetic nanoparticles using an inductive measurement technique. The 10nm particles are placed directly on a coplanar waveguide (CPW) situated in an adjustable external magnetic bias field. A fast-rising step current in the CPW quickly changes the orientation of the local magnetic field causing the magnetization to align in the new field configuration. This rapidly changing magnetization induces a voltage in the CPW that is detected by a sampling oscilloscope. Magnetization dynamics predicted by the Landau-Lifshitz (LL) equation including magnetic precession and phenomenological damping are observed. The time-domain data are fitted to …

Visibility-Based Pursuit-Evasion In The Plane, Nicholas Michael Stiffler

Theses and Dissertations

As technological advances further increase the amount of memory and computing power available to mobile robots, we are seeing an unprecedented explosion in the utilization of deployable robots for various tasks. The speed at which robots begin to enter various domains is largely dependent on the availability of robust and efficient algorithms that are capable of solving the complex planning problems inherent to the given domain. One such domain which is experiencing unprecedented growth in recent years requires a robot to detect and/or track a mobile agent or group of agents.

In these scenarios, there are typically two players with …

Development Of Highly Active And Stable Compressive Pt Cathode Catalysts For Polymer Electrolyte Membrane Fuel Cells, Taekeun Kim

Theses and Dissertations

With the limited fossil fuel reserve and increased power demand, polymer electrolyte membrane fuel cells (PEMFC) have been considered to be a promising alternative to the current energy consumption mode due to its high energy conversion, high efficiency, and zero emissions. However, high cost, poor stability, and sluggish kinetic for oxygen reduction reaction (ORR) of Pt/C cathode catalysts are obstacles for the commercialization of PEMFC for automotive application. The observed poor stability is attributed to a corrosion of carbon supports due to low pH, high temperature, and high anodic potentials (1.0-1.5 V) at the cathode interface during start-up/shutdown conditions. Electrochemical …

Modeling Human-Structure Interaction Using A Controller System, Albert Ricardo Ortiz Lasprilla

Theses and Dissertations

The effects of human loads on structures are difficult to predict because they depend on the type of activity people are performing. However, models for typical activities such as standing, sitting and jumping have been proposed in the literature. Traditional models represent the human body as a system of lumped masses, dampers and springs arranged in a system with multiple degrees of freedom. Arguably, these models might not fully represent the human body because lumped masses, dampers and springs cannot add energy to the overall system. Furthermore, people could react differently to different levels of excitation and other environmental conditions. …

Adsorption Reversibility Of So2, No2, And No On 13x And 5a Zeolites, Peter Fairchild

Theses and Dissertations

The adsorption reversibility of gasses that are typically found in flue gas for coal based power plants, such as SO2, NO2, and NO, onto 13X and 5A zeolites was presently investigated. The four individual gas mixtures containing these species consisted of 74 ppm NO (balance He), 74 ppm NO2 (balance He), 42 ppm SO2 (balance He), and 500 ppm SO2 (balance N2), which were also consistent with the values that are found in flue gas. Another gas, 15.03 mol% CO2 (balance N2), was also used in this work to evaluate the role of exposing SO2 to the zeolite on their …

Modeling And Loss Analysis Of Wide Bandgap Power Semiconductor Devices, Kang Peng

Theses and Dissertations

In recent times, the development of high power density and high efficiency power converters has become critical in power electronics applications like electric vehicles, aircrafts, electric ships and so on. High-switching-frequency and high-temperature operation are required to achieve this target. However, these requirements are exceeding the theoretical material-related limits of silicon (Si) based devices. The emerging wide bandgap power semiconductor technology is a promising solution to meet these requirements. Silicon Carbide (SiC) and Gallium Nitride (GaN) are the most promising among all wide bandgap semiconductor materials. SiC and GaN have almost a three times larger bandgap (about 3eV), compared with …

Engineered Earthen Masonry Structures For Extreme Wind Loads, Mabel Cristina Cuellar-Azcarate

Theses and Dissertations

Stabilized earthen masonry (SEM), which is built with compressed stabilized earthen blocks (CSEB) and mortar, is emerging as a construction system for affordable, sustainable and high-quality dwellings. Compelling features of earthen masonry are local availability of suitable soils, thermal insulation properties, humidity control within healthy ranges, and relatively low carbon footprint. SEM is also appealing for the construction of affordable houses in rural areas and farmlands, where underrepresented and underprivileged groups often live. In fact, the lack of affordable housing is an issue across the United States where low-income families are most affected, often committing more than half of their …

Polyphenols As Natural, Dual-Action Therapeutics For Alzheimer's Disease, Kayla M. Pate

Theses and Dissertations

Alzheimer’s disease (AD), the most common form of dementia, is characterized by extracellular plaques in the brain created when monomeric amyloid-β (Aβ) protein aggregates into fibrillar structures. Soluble Aβ aggregates, including oligomers, that form along the reaction pathway are believed to be the primary pathogenic species and have been shown to increase the production of reactive oxygen species (ROS). This upregulation of ROS is one suggested contributing factor of Aβ aggregate cytotoxicity and has proven capable of mediating cell signaling associated with Aβ aggregate-induced cellular responses.

Polyphenols have been suggested as a complimentary AD therapeutic based on epidemiological evidence that …

Numerical Modeling Of Heat Transfer And Material Flow During Friction Extrusion Process, Hongsheng Zhang

Theses and Dissertations

Friction extrusion process is a novel manufacturing process that converts low-cost metal precursors (e.g. powders and machining chips) into high-value wires with potential applications in 3D printing of metallic products. However, there is little existing scientific literature involving friction extrusion process until recently. The present work is to study the heat transfer and material flow phenomena during the friction extrusion process on aluminum alloy 6061 through numerical models validated by experimental measurements.

The first part is a study of a simplified process in which flow of a transparent Newtonian fluid in a cylindrical chamber caused by frictional contact with a …

Finite Control Set Model Predictive Control Of Direct Matrix Converter And Dual-Output Power Converters, Ozan Gulbudak

Theses and Dissertations

Model Predictive Control (MPC) with a finite control set has been successfully applied to several power converter topologies as reported in the scientific literature and research activity on predictive control techniques has increased over the last few years. MPC uses a discrete-time model of the system to predict future values of control variables for all possible control actions and computes a cost function related to control objectives to find the optimal control action. The control action which minimizes the cost function is selected and applied to the system for the next time interval. Different control objectives can be introduced in …

Ultrathin Microporous Metal Oxide Coatings: Preparation By Molecular Layer Deposition, Characterization And Application, Zhuonan Song

Theses and Dissertations

Molecular layer deposition (MLD), a gas phase deposition technique, was applied to deposit conformal organic-inorganic hybrid coatings by conducting a series of sequential, self-limiting surface reactions on substrates with exquisite thickness control at the sub-nanometer level. Obtained organic-inorganic hybrid coatings can subsequently be converted into porous coatings by removing the organic compound. Potential of functional coatings and membranes prepared by MLD was explored for applications from adsorptive separation, water purification, to gas storage.

We demonstrated a new concept, pore misalignment, to continuously fine tune the molecular-sieving “gate” of 5A zeolite by adjusting the external porous Al2O3 MLD coating thickness. For …

Distributed Optimization And Control Of Islanded Microgrids, Md Rishad Hossain

Theses and Dissertations

A microgrid may have numerous multi-functional power electronic converters connecting sources, loads, and storage to the system. Systems where converters are the interface between many of the main sources of energy and load centers have the ability to direct the flow of energy if the control of the converters is coordinated. The influence of energy flow in a microgrid by coordinated action of converters is referred to here as ‘energy routing’. Energy routing allows for reduction of systems losses by optimizing source operating points and reducing transmission and distribution path losses. Energy ramp rates at various points in the system …

Life-Cycle Analysis Of A Cement Manufacturing Plant Co-Firing Hazardous Waste In The Usa, Stephen P. Holt

Theses and Dissertations

The purpose of this work was to determine the overall environmental impacts associated with the co-firing hazardous waste by burning in a cement kiln to replace the use of coal in the cement manufacturing process. This environmental assessment was conducted using LCA methodology. Understanding the environmental impacts associated with burning hazardous waste in a cement factory could help shape national environmental policy, regulations and the need for site specific human health risk assessments in the environmental regulatory permitting processes. Accordingly, the primary objective of this study was to evaluate the environmental impacts from the hazardous waste burning for energy recovery …

Improving Cooling Tower Chemistry Control And Cost Savings Through Automation, Ryan Matthew Maxwell

Theses and Dissertations

Proper chemistry control of cooling towers reduces corrosion, biological growth, and precipitation of solids. Therefore, improving control can lead to increased equipment life, operating efficiency, and safety. Chemistry of cooling towers is highly dependent on loading, weather, and time. As such, cooling tower chemistry varies day to day and even hour to hour, requiring either continuous controls or large operating bands. Through automation, 24/7 monitoring and control can be achieved, allowing for deliberate operation within tight operating bands. As a direct result of automation water consumption has been reduced by 9.1 million gallons per year, CL-49 use has been reduced …

Wireless Channel Modeling For Networks On Chips, William Rayess

Theses and Dissertations

The advent of integrated circuit (chip) multiprocessors (CMPs) combined with the continuous reduction in device physical size (technology scaling) to the sub-nanometer regime will result in an exponential increase in the number of processing cores that can be integrated within a single chip. Today’s CMPs already support tens to low hundreds of cores and both industry and academic roadmaps project that future chips will have thousands of cores. Therefore, while there are open questions on how to harness the computing power offered by CMPs, the design of power-efficient and compact on-chip interconnection networks that connects cores, caches and memory controllers …

Friction Stir Welding And Processing On Titanium Alloys, Dawei Li

Theses and Dissertations

Friction stir welding (FSW) is a solid-state joining process that utilizes a non-consumable, rotating tool to plunge into abutting faces and transverse along the weld path. Material nearby the tool is softened by frictional heat generated via local friction and plastic deformation. Severe plastic deformation of the interface along with a state of hydrostatic pressure results in creation of a joint by metallurgical bonding. Because the temperature of the material during the welding process is below that of the melting point, FSW has numerous advantages over conventional fusion welding. Friction consolidation (FC) is also a solid-state process that uses a …

Computational Doping For Fuel Cell Material Design Based On Genetic Algorithms And Genetic Programming, Emrah Atilgan

Theses and Dissertations

Developing new materials have historically been time-consuming. Computational material discovery can search large design space to identify promising candidates for experimental verification. Recently, Density Functional Theory (DFT) based first principle calculation has been able to calculate many electrical and physical properties of materials, making them suitable for computational doping based material discovery. In material doping, given a base material, one can change its properties by substituting some elements with new ones or adding additional elements. In computational doping, we have a grid of atoms in a supercell, some of which can be substituted with dopant atoms. There are many possible …

Age-Related Liquefaction Resistance Of Pleistocene Coastal Plain Sands In South Carolina, Michael J. Hasek

Theses and Dissertations

Soils of Pleistocene age in the South Carolina Coastal Plain have experienced liquefaction due to historic and pre-historic earthquakes. Numerous field and laboratory studies have shown that aged soil deposits maintain a greater resistance to liquefaction than younger soil deposits. The currently available methods for assessing liquefaction potential are based on cases in which soils are of Holocene age or younger (< 10,000 yrs). The Pleistocene age soils that were tested and characterized varied in age from about 200,000 years old to 1,400,000 years old. Several sites were investigated using field methods that included the seismic cone penetration test, cone penetration test, standard penetration test, and flat plate dilatometer. Piezometers were installed at the sites. Undisturbed soil samples were retrieved from the subsurface and frozen ex situ to minimize sample disturbance during transportation and laboratory handling. The undisturbed samples were used for cyclic triaxial testing in the laboratory and were tested for shear wave velocity and compression wave velocity using in-cell transducers. Laboratory tests were performed to determine the specific gravity, grain size distribution, moisture content, unit weight, Atterberg limits, Unified Soil Classification, and visual-manual description. Optical petrography and scanning electron microscopy were used to determine the mineral content of the soils, to view grain characteristics, and to view microscopic features that were part of the soil aging process.

Laboratory index tests showed that Pleistocene soils consisted predominately of poorly-graded fine sands, silty sands, and clayey sands. Shear wave velocities from the cyclic triaxial test specimens were comparable to the in situ shear wave velocities measured using …

Engineering Model Of Iii-Nitride Power Heterostructure Field Effect Transistor On Silicon Substrate, Mohammad Mirwazul Islam

Theses and Dissertations

In modern society, the demand for power consumption is increasing rapidly and the need of energy savings is now an issue of global importance. Highly efficient power converters and power conditioning systems operating with wide range of traditional as well as novel renewable and clean energy sources, are playing crucial role in energy saving. Si converters have already reached their limitation in terms of switching frequency and breakdown voltage/on-resistance ratio. Research is going on all around the world and it is now well accepted that significant improvement in power conversion efficiency and speed can only be achieved using beyond Si …

Mechanical Characterization Of Sicf-Sicm Nuclear Fuel Cladding By A Novel Hydraulic Internal Pressurization Method, Kirill Shapovalov

Theses and Dissertations

Ceramic Matrix Composites (CMC) have been actively researched for applications requiring high temperature strength and damage tolerance. Examples are turbine engine hot section components, leading edges for hypersonic vehicles, nuclear fusion reactor first wall and blanket, and recently nuclear fuel claddings. Predictable material damage behavior is desirable for these applications so early damage accumulation can be detected before a catastrophic failure occurs. Many ceramic materials can withstand high temperature environments, but due to inherent brittleness of ceramics the high damage tolerance and the predictable damage behavior are difficult to achieve. Ceramic fiber reinforced ceramic composites (CFCC) have demonstrated the above …

Implementation Of Agile Project Management In The Classroom, Michael Jerrod Myers

Theses and Dissertations

The world of engineering and engineering practices is advancing rapidly. In response to this rapid change, engineering education practices have to advance to ensure students are properly trained for the workforce. The purpose of this report is to address and substantiate the hypothesis that if engineering instruction incorporated Agile project management methods, then students will be challenged by professors to accomplish course objectives with a systematic and timely approach that will improve assessment performance metrics and present the framework of how agile methods of project management can be integrated into the classroom. The agile methods incorporated will also encourage the …