Digital Commons Network^™

Experimental Study On Piping Failure Of Earthen Levee And Dams, Yusuf Ahmed Sharif

Theses and Dissertations

Piping in an earthen levee, one of the main causes of failure, is a complex phenomenon. Most of the available research on piping failure has been on non-cohesive sandy soils. Jet Erosion Test and Hole Erosion Test have been conducted to study piping failure in an indirect manner. However, no general purpose formula is presently available to describe the erosion process due to complex erosion characteristics of cohesive soils in earthen levees.

Experimental investigations in a flume to understand the piping erosion process in an earthen levee are conducted in this research. One of the sidewalls and the bottom of …

Multi-Label Segmentation Propagation For Materials Science Images Incorporating Topology And Interactivity, Jarrell Waggoner

Theses and Dissertations

Segmentation propagation is the problem of transferring the segmentation of an image to a neighboring image in a sequence. This problem is of particular importance to materials science, where the accurate segmentation of a series of 2D serial-sectioned images of multiple, contiguous 3D structures has important applications. Such structures may have prior-known shape, appearance, and/or topology among the underlying structures which can be considered to improve segmentation accuracy. For example, some materials images may have structures with a specific shape or appearance in each serial section slice, which only changes minimally from slice to slice; and some materials may exhibit …

Quantifying Regional-Scale Water Storage Using Models And Observations: Application For Drought Assessment In South Carolina, Mirza Md Mozaddid Billah

Theses and Dissertations

Hydrologic models are widely used to determine the occurrence and severity of droughts, and to aid in the decision making process for reducing drought impacts. These models apply approaches including water and energy balance equations to determine water availability at field to continental scales. One challenge in implementing hydrologic models at larger scales (regional to continental) is the lack of data with sufficient spatial and temporal resolution to represent actual conditions within the modeling domain. If such data is available, the challenge remains how best to find, access, and process the data so that it can be used within hydrologic …

Removal Of Synthetic Organic Compounds And Nom By Single-Walled Carbon Nanotubes-Ultrafiltration And Forward Osmosis Membrane System, Jiyong Heo

Theses and Dissertations

This overall theme of this dissertation is to investigate the potential engineered application of low pressure membranes incorporated with single-walled carbon nanotubes (SWNTs) and forward osmosis (FO) membrane systems for the removal of synthetic organic compounds (SOCs) and natural organic matter (NOM) from drinking water sources. The focus is on the use of SWNTs-ultrafiltration (UF) and FO membrane systems to facilitate the removal of these compounds and potential applications of these membrane system designs for reducing the energy demands and membrane fouling in environmental water filtration process and seawater desalination. The SWNTs-UF results indicate that SOCs transport is influenced by …

Stabilizing Controller Design For A Dc Power Distribution System Using A Passivity-Based Stability Criterion, Antonino Riccobono

Theses and Dissertations

In modern times there has been an increased penetration of power electronic converters into Power Distribution Systems. In particular, there has been a strong interest in DC Power Distribution Systems as opposed to conventional AC Power distribution systems. These DC Power Distribution Systems are enabled by power electronics converters. The strong interest is motivated by improvements in power electronic converter technology, like advances in power semiconductor devices, magnetics, control, and converter topologies which have made possible to build high-performance converters at low cost. In many systems, such as cars, ships and airplanes, there has also been a trend towards the …

Studying On Capacity Fade Mechanisms Of Li-Ion Batteries Through Modeling, Yiling Dai

Theses and Dissertations

Li-ion batteries are promising candidates as power sources for hybrid electric/electric vehicles, as well as storage devices for renewable energies (wind, solar). Longer life batteries are more desirable for large-scale application, which would help lower the capital cost ($/KW) and improve the system stability. However, the aging problem of Li-ion batteries obstructs their fast penetration into these markets. The cell life can be improved based on an in-depth understanding of the fade mechanisms. The purpose of this dissertation is to explore, through a mathematical modeling approach, failure mechanisms of Li-ion batteries.

To study the capacity fade of a LiMn2O4 (LMO) …

Coordinated Control Of Power Electronic Converters In An Autonomous Microgrid, Gholamreza Dehnavi

Theses and Dissertations

Advances in power electronics and generation technologies have increased the viability of distributed generation systems. A microgrid is a special category of distributed generation systems that is distinguished by its size and the ability to operate independently as an islanded system. As long as a microgrid is connected to a large grid, quality of the voltage is supported by the main grid and each power source connected to the microgrid generates independently. In contrast, in the islanded operation of microgrids and in electrical islands such as shipboard distribution systems, dynamics are strongly dependent on the connected sources and on the …

Enantioselective Hydrogenation Of Α-Methylcinnamic Acid Over Pd/Al2o3: A Spectroscopic And Kinetic Study, Xiaojing Sun

Theses and Dissertations

Hydrogenation of C=C in α-methylcinnamic acid (MCA) is studied by both kinetic and spectroscopic method. Kinetic study was in a semi-batch reactor. The reaction activity is strongly solvent dependent, while selectivity remains almost unaffected. The reaction is zero order in hydrogen pressure and first order in MCA. The presence of cinchonidine does not affect the reaction order with respect to either acid or H2 pressure, but has a significant inhibiting effect on the reaction rate. The catalyst exhibits stable activity during the reaction with no sign of deactivation. The adsorption and hydrogenation in dichloromethane, isopropanol and 1, 4-Dioxane over the …

Quasinovo: Algorithms For De Novo Peptide Sequencing, James Paul Cleveland

Theses and Dissertations

High-throughput proteomics analysis involves the rapid identification and characterization of large sets of proteins in complex biological samples. Tandem mass spectrometry (MS/MS) has become the leading approach for the experimental identification of proteins. Accurate analysis of the data produced is a computationally challenging process that relies on a complex understanding of molecular dynamics, signal processing, and pattern classification. In this work we address these modeling and classification problems, and introduce an additional data-driven evolutionary information source into the analysis pipeline.

The particular problem being solved is peptide sequencing via MS/MS. The objective in solving this problem is to decipher the …

Plc Code Vulnerabilities Through Scada Systems, Sidney E. Valentine, Jr.

Theses and Dissertations

Supervisory Control and Data Acquisition (SCADA) systems are widely used in automated manufacturing and in all areas of our nation's infrastructure. Applications range from chemical processes and water treatment facilities to oil and gas production and electric power generation and distribution. Current research on SCADA system security focuses on the primary SCADA components and targets network centric attacks. Security risks via attacks against the peripheral devices such as the Programmable Logic Controllers (PLCs) have not been sufficiently addressed.

Our research results address the need to develop PLC applications that are correct, safe and secure. This research provides an analysis of …

Effect Of Physiological Oxygen Levels On Osteogenic Differentiation Of Adipose-Derived Stem Cells, Suchit Sahai

Theses and Dissertations

Regenerative medicine presents exciting strategies for healing critical-size bone defects through the implantation of cells and biocompatible scaffolds. Most in vitro studies are performed in atmospheric oxygen conditions (~20%), which do not accurately mimic the CSD microenvironment. Due to damage to the vasculature at CSDs, oxygen levels fall into the hypoxic range (<5%), which can impact viability, proliferation and differentiation of the cells employed for bone regeneration. Understanding the cellular responses to hypoxia has grown primarily from study of individual molecular factors. The master regulator of adaptive responses to low oxygen availability is the nuclear factor, hypoxia-inducible factor-1. HIF-1 is a heterodimeric protein, stable below 6% O2 condition in the nucleus and has been shown to play a role in angiogenic-osteogenic coupling. We have developed a responsive, fluorescent, hypoxia detection system and determined whether HIF activity can be tracked in both 2-D and 3-D cultures. Adipose-derived stem cells (ASCs) were selected due to their broad utilization in tissue engineering strategies and characterized the influence of HIF signaling on its phenotype. The work done identified that of hypoxia impaired osteogenic differentiation of ASCs in both 2-D and 3-D cultures and HIF-1 did not mediate this effect. Ischemic preconditioning (IPC) strategy and varied protocols used represents a clinically feasible manipulation of cell preparation to help the survival of implanted ASCs and accelerate osteogenic differentiation at physiological oxygen levels.

Characterizing Hypoxia And Its Behavioral Effects In 3-Dimensional Cell Aggregates, Matthew Lorincz Skiles

Theses and Dissertations

Cell transplantation can be considered a regenerative therapy, an intervention which attempts to replace or restore the function of compromised tissue by harnessing innate properties of cells that cannot be replicated artificially. For such therapies to succeed, it will be necessary to understand and closely match the physiological conditions that govern cell behaviors in vivo. One important factor is low oxygen tension, termed hypoxia, which is often overlooked in vitro. Because oxygen insufficiency can lead to cell death, hypoxia has traditionally been viewed as a negative condition. However, hypoxia can also serve as a potent regulator of crucial cell behaviors …

Theoretical Investigation Of The Water-Gas Shift Reaction At The Three Phase Boundary Of Ceria Supported Platinum Metal Clusters, Sara Aranifard

Theses and Dissertations

The Water-Gas Shift (WGS: CO+H2O→CO2+H2) reaction is a key step in hydrogen fuel processing for mobile fuel cell applications. Since the reaction is equilibrium-limited and exothermic, high conversions are favored by low temperatures. However, conventional low-temperature shift catalysts are not active enough. Reducible oxide supported small noble metal clusters have shown excellent activity as low temperature WGS catalysts and it is generally believed that these catalysts are bifunctional. In other words, the reaction occurs at the three-phase boundary (TPB) of the noble metal, the reducible oxide, and the gas phase. The small noble metal cluster adsorbs/activates the CO molecules and …

Understanding The Effect Of Balance Of Plant Contaminants On Pemfcs Performance: Models, Mechanisms, Functional Group, Hyun-Seok Cho

Theses and Dissertations

This dissertation considers contamination of a proton exchange membrane fuel cell (PEMC) that may result from chemicals that leach from balance of plant (BOP) materials. Both model predictions and experimental data are presented. The model is used to predict the cathode contamination impact on the Pt/C electrode and the membrane assuming no transport of contaminant from cathode to anode. The model prediction accounts for the contamination mechanisms such as adsorption, ion-exchange, absorption and three sources of voltage (i.e., performance) loss. The simple 2-D time-dependent model is developed by considering well known chemical engineering concepts of Langmuir adsorption, partition coefficients, plug …

Investigation Of Three-Way (Twc), Lean Nox Trap (Lnt) And Selective Catalytic Reduction (Scr) Catalysts For Control Of Nox Emissions From Lean-Burn Engines, Christopher Dominic Digiulio

Theses and Dissertations

Lean-burn gasoline engines are approximately 10% more fuel efficient than conventional, stoichiometric-burn ones. Although relatively modest, if implemented across the entire U.S. automotive fleet, this improvement in fuel economy could have far-reaching implications on the amount of gasoline imported in the country on an annual basis. However, the development of a cost-effective catalytic converter catalyst capable of meeting emission regulations for lean-burn vehicles still represents a major technical challenge. Currently, lean NOX trap (LNT) and selective catalytic reduction (SCR) catalysts are used for this purpose, but both systems suffer from significant drawbacks. For example, LNT catalysts generally require high platinum …

Assessment Of Damage In Concrete Structures Using Acoustic Emission, Marwa Abdelrahman

Theses and Dissertations

Evaluating the integrity of concrete structures is an essential procedure to ensure structural safety and durability. Non-destructive testing (NDT) is needed for localizing and characterizing the growing damage in existing structures and also for quality control of new structures. Visual inspection is a commonly used method; however it is not suitable for early detection of damage and very dependent on the experience of the inspector. More research is needed to establish advanced methods for structural health diagnosis such as acoustic emission (AE). Acoustic emission is notably sensitive to active damage in concrete structures. This thesis includes three studies that mainly …

High Fat Diet Induced Obesity In A Mouse Model For Colorectal Cancer, Kennerly Clinton Patrick

Theses and Dissertations

Obesity is widely correlated with the incidence of colorectal cancer (CRC). The exact mechanisms that link obesity to CRC risk have not yet been fully established, and only a limited number of animal models are available to study pathways involved in obesity-related colon carcinogenesis. The objective of this study was to determine the influence of HFD-induced obesity on AOM/DSS-mediated colorectal tumorigenesis, tumor proliferation, and symptom severity. Male C57BL/6 mice were fed a novel high fat diet, designed to mimic the standard American diet (12 % saturated fat & 28 % unsaturated fat), at 4 weeks of age until 16 weeks …

Design And Analysis Of An Electronically Steerable Microstrip Patch And A Novel Coplanar Waveguide (Cpw) Fed Slot Antenna Array, Hamad Shaban Aldossary

Theses and Dissertations

Conformal Phased Array Antennas (CPAAs) are very attractive for their high gain, low profile, and beam scanning ability while being conformal to their mounting surface. Among them are microstrip patch phased arrays and wideband slot phased arrays which are of particular significance.

In this work, first the study, design, and implementation of a conformal microstrip patch phased array is presented which consists of a high gain beam scanning array implemented using microstrip delay lines controlled using GaAs SPDT switches. Then the study and design of a wideband Coplanar Waveguide (CPW)-fed slot phased array antenna is presented. In both cases the …

Emulation Of An Aeroderivative Twin-Shaft Gas Turbine Engine Using An Ac Electric Motor Drive, Blanca A. Correa

Theses and Dissertations

This dissertation presents a method to use an electric motor to emulate the steady-state and transient shaft power characteristics of an aeroderivative twin-shaft turbine engine. Model-based control provides the framework for developing an aeroderivative twin-shaft engine emulation system. Criteria are developed to appropriately specify the motor and variable-speed drive, based on torque, power, and inertia. This method accounts for the difference in inertia between the engine and the emulating motor; it establishes for the first time the nominal and peak torque requirements of the machine and the peak power and current requirements of the electronic motor drive (inverter).

Our results …

Accelprint:Accelerometers Are Different By Birth, Sanorita Dey

Theses and Dissertations

This paper submits a hypothesis that smartphone accelerometers possess unique fingerprints. We believe that the fingerprints arise from hardware imperfections during the sensor manufacturing process, causing every sensor chip to respond differently to the same motion stimulus. The differences in responses are subtle enough that they do not affect most of the higher level functions computed on them. Nonetheless, upon close inspection, these fingerprints emerge with consistency, and can even be somewhat independent of the stimulus that generates them. Measurements and classification on 80 standalone accelerometer chips, 25 Android phones, and 2 tablets, show precision and recall upward of 96%, …

Accelerating Short Read Mapping Using A Dsp Based Coprocessor, Shaun I. Gause

Theses and Dissertations

Advances in next generation sequencing technologies have allowed short reads to be generated at an increasing rate, shifting the bottleneck of the sequencing process to the short read mapping computations. High costs and extended processing times drive researchers to pursue more efficient solutions with an overall goal of a short read mapping architecture capable of processing short reads as they are generated. Digital signal processors have shown high performance capabilities while maintaining low power consumption in a wide field of applications. This thesis explores the use of a DSP accelerated exact match short read mapping algorithm, focusing on a performance …

Assessing Corrosion Damage In Post -Tensioned Concrete Structures Using Acoustic Emission & A Preliminary Investigation Of Biopolymer Doped Cement Mortar For Use In Structural Restoration, Aditya Appalla

Theses and Dissertations

A sizeable portion of the civil infrastructure is made from concrete. An estimate shows that about 7 billion cubic meters of concrete is made annually worldwide. With the deterioration of the infrastructure due to aging or external factors, significant monetary and technological investment is needed for condition evaluation, maintenance and repair. Two areas that account for a considerable portion of this investment are condition evaluation for maintenance of corroded concrete structures and mortar patching for repair and rehabilitation.

The primary method of evaluation of a structure is by visual inspection. But this method is limited as some crucial areas in …

Syntactic And Semantic Interoperability Among Hydrologic Models, Mostafa Mohamed Elag

Theses and Dissertations

Development of integrated hydrologic models requires coupling of multidisciplinary, independent models and collaboration between different scientific communities. Component-based modeling provides an approach for the integration of models from different disciplines. A key advantage of component-based modeling is that it allows components to be created, tested, reused, extended, and maintained by a large group of model developers and end users. One significant challenge that must be addressed in creating an integrated hydrologic model using a component-based approach is enhancing the interoperability of components between different modeling communities and frameworks. The major goal of this work is to advance the integration of …

Fabrication And Characterization Of Surrogate Fuel Particles Using The Spark Erosion Method, Kathryn Elizabeth Metzger

Theses and Dissertations

In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy's Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile …

Dislocation Reduction In Silicon Doped High Aluminum Content Algan Layers For Deep Uv Optoelectronic Devices, Hung-Chi Chen

Theses and Dissertations

III-Nitride based deep ultraviolet (UV) light emitting diodes (LEDs) are prospective candidates to replace the conventional bulky, expensive and environmentally harmful mercury lamp as new UV light sources, used in the applications of water and air purification, germicidal and biomedical instrumentation systems, etc. Due to the lack of native substrates and poor carrier injection, AlGaN-based deep UV LED is suffering from low optical power and low overall efficiency, which prevents the availability of low cost, high efficiency deep UV LED on the market.

This dissertation is focused on improving the efficiency of deep UV LEDs, by improving the base template …

Impedance Estimation Using Randomized Pulse Width Modulation And Power Converters, William M. Mccoy

Theses and Dissertations

With the adoption of technologies such as alternative energy production, DC power grids, and electric vehicles, the use of high power switching converters has seen a dramatic increase. These power converters serve many rolls such as grid-tied inverters in solar farms, high power charging for electric vehicles, motor drives for industrial applications, and DC links in transmission systems. With the increased prevalence of such devices, it is only natural to attempt to optimize their operation. As with any level of converter, it is desirable to have accurate control over the generated voltages and currents. Often, these controllers implement some form …

High Performance Rf Control Devices Using Capacitively Coupled Contacts (C3) Over Iii-N Heterostructures, Faisal Jahan

Theses and Dissertations

RF switches, power limiters and other control devices are essential components of modern RF systems. RF switches are important parts of wireless modules of various devices such as laptops, tablets, cell phones etc. and key components of satellites communication systems, radars, multi-band wireless and aerospace communications, phased array antennas. RF Power limiters (PL) are also important components of RF systems protecting linear amplifiers, detectors etc. from high-power stress. Traditionally, RF switches are fabricated using pin diodes or MEMS, Si MOSFETs or GaAs HEMTs. RF PLs are typically implemented using Schottky or pin-diodes. Traditional devices used in RF switch and PLs …

High Resistivity Amorphous Selenium Alloy Semiconductors For Radiation Detection Applications, Abhinav Mehta

Theses and Dissertations

High resolution noninvasive tools of diagnosis has always derived and enabled scientific and medical research to probe and better understand subtleties of matter, intangible to the human eye. Radiation detection systems are highly dependent on advancements in materials and devices with front-end electronics. There are various discrete applications of these radiation detectors and each application imposes certain requirements so there is no single optimum radiation detector.

Flat panel x-ray imagers have gained high demand in the past decade because of exponential improvement in readout electronics. We have synthesized and investigated stabilized amorphous selenium (a-Se) alloys suitable for high resolution flat …

Wireless Pressure Sensor System For Medical Applications, Xuehe Wang

Theses and Dissertations

Telemedicine in the modern era is a rapidly developing industry. In a telemedicine system, sensor is the key elements and play important role in any telemedicine applications, especially implantable sensors. Unlike traditional in vitro sensors, there are some special requirements for them like battery-less, compact, and bio-friendly. Therefore, many researchers in institutes as well as in industry are continually developing implantable sensor and sensor system to fulfill the requirements of medical applications.Nine in one thousand people in the United States are born with congenital heart defects and sixty percent die before one year old. As a result, it will be …

Iii-V Nitride Micro- And Nano-Scale Cantilevers For Multimodal Sensing Applications, Ehtesham Bin Quddus

Theses and Dissertations

Recent research trends in chemical and biological sensing have been geared toward developing molecular sensor devices that are fast, label free, miniaturized and portable. The performance of these devices can be dramatically improved by utilizing multimodal detection techniques, new materials and micro-/nanofabrication technologies. This is especially true for micro-/nanoscale cantilever sensors, which undergo changes in mechanical or electrical properties upon the specific binding of molecules. To develop the sensor devices with the above attributes, we utilized III-V nitride materials: InN nanowires for realizing nanoscale cantilevers and AlGaN/GaN heterostuctures with or without embedded HFETs, for developing microcantilevers. There are mainly two …