Digital Commons Network^™

Using Data Assimilation To Investigate The Effect Of African Easterly Waves, Mesoscale Convective Systems, And Orography On Tropical Cyclogenesis Over Eastern Pacific, Gregory N. Terkper

Theses

This study examines the association of tropical cyclogenesis and tropical wave activities such as African Easterly Waves (AEWs) in the Northeast Pacific Ocean. The impact of Central and Mexico Mountains on hurricane genesis, intensification and track is also studied in this paper. Eight numerical simulations using Weather Research and Forecasting (WRF-ARW) model are conducted to investigate the genesis, track and intensification of Hurricane Jimena (2009) a category 4 (on the Saffir-Simpson Hurricane Scale) hurricane during the 2009 eastern Pacific hurricane season. In addition, this study also analyzes the impact of three dimensional variational data assimilation of (3DVAR) of NCEP FNL …

Examination Of Thermal Properties Of Carbon-Carbon And Graphitized Carbon-Carbon Composites, Melanie Jene' Patrick

Theses

Thermal characterization of composites is essential for their proper assignment to a specific application. Specific heat, thermal diffusivity, and thermal conductivity of carbon-carbon composites are essential in the engineering design process and in the analysis of aerospace vehicles, space systems and other high temperature thermal systems. Specifically, thermal conductivity determines the working temperature levels of a material and is influential in its performance in high temperature applications. There is insufficient thermal property data for carbon-carbon composites over a range of temperatures. The purpose of this research is to develop a thermal properties database for carbon-carbon composites that will contain in-plane …

Application Of Adaptive Extended Kalman Filtering Scheme To Improve The Efficiency Of A Groundwater Contaminant Transport Model, Elvis Boamah Addai

Theses

Pollution of groundwater can be harmful to the environment. The use of subsurface contaminant transport models, combined with stochastic data assimilation schemes, can give on-target predictions of contaminant transport to enhance the reliability of risk assessment in the area of environmental remediation. Observation data are required to guide the deterministic system model to assimilate the true state of the contaminant. Modeling the behavior of contaminant in groundwater is imperative in predicting the fate of the pollutant, in risk assessment, and as a preceding step of the remission process. In this study a two-dimensional transport model with advection and dispersion is …

Alzheimer's Disease Literacy In The African American Community, Angel Mckenzie Watson

Theses

Alzheimer's disease (AD) is a public health crisis in the African American (AA) community, as evidenced by both increased prevalence and familial risk among African Americans. African Americans are two times as likely to suffer with this disease, are diagnosed later in the disease process, and are considered to have less factual information about AD when compared to their white counterparts. Late diagnosis has been associated with significantly higher dementia-related morbidity and health care costs. Moreover, studies have shown that patients with increased health literacy have better health outcomes. Therefore, we want to assess how well African Americans understand Alzheimer's …

Synthesis And Characterization Of Hydroxyapatite Doped With Strontium Carbonate Thin Film Coatings, Stephen Ayodeji Ajinola

Theses

The main purpose of the research is to investigate the corrosion rate and mechanical properties of thin film of strontium carbonate (Sr2CO3) doped with hydroxyapatite (HA) on titanium substrates using DC Corrosion of Potentiodynamic and Nanoindentation respectively. The variation in the weight percentages of strontium carbonate in hydroxyapatite on a titanium substrate was used to investigate the beneficial effect of strontium on surface modification in biological application such as to improve hardness of dentures and prevention of cavities, menopause bone loss and enhancement of remodeling. The corrosion rate, the hardness and elastic moduli of different weight percents of variation in …

Experimental Investigation And Aspen Plus Simulation Of The Msw Pyrolysis Process, Emmanuel Ansah

Theses

Municipal solid waste (MSW) is a potential feedstock for producing transportation fuels because it is readily available using an existing collection/transportation infrastructure and fees are provided by the suppliers or government agencies to treat MSW. North Carolina with a population of 9.4 millions generates 3.629 million metric tons of MSW each year, which contains about 113,396,356 TJs of energy. The average moisture content of MSW samples is 44.3% on a wet basis. About 77% of the dry MSW mass is combustible components including paper, organics, textile and plastics. The average heating values of MSW were 9.7, 17.5, and 22.7 MJ/kg …

Using Multiple Air Models To Form A Superensemble, Frank Gronwald

Theses

Determining the level of air pollution is a modern day necessity for government regulators and industrialized sources. Air dispersion models are often used to determine the concentration of a pollutant. However changing conditions and several assumptions made by the models limit their accuracy at various times. This research proposed combining four different air dispersion models (Gaussian Plume, Variable K Theory, Box, and AFTOX) into a superensemble. Since the superensemble is typically more accurate than its member models, the end result should be a more accurate prediction under any condition. In the interest of evaluating performance, the change in accuracy was …

Rating Curve Development And Multivariate Statistical Analyses Of Stream Water Quality In Greensboro, North Carolina, Bhasker Jha

Theses

A suite of regression models were tested for the construction of rating curves and constituent load estimation for 17 water quality parameters monitored at 16 stations regularly since 1999 by the City of Greensboro in North Carolina. Best models were selected based on the statistical evaluation within the framework of the LOAD ESTimator (LOADEST) model. The constituent prediction varied from the "true load" by -“6% to 16% for Nitrate; -14% to +12% for Nitrite; -6% to 0% for Total Dissolved Solids (TDS); -2% to 9% for Total Kjeldahl Nitrogen (TKN); -22% to 9% for Total Phosphorus (TP); and -51% to …

Information And Communications Technology Based Solution To Rank Emergency Hospitals, Taneaka Anesha Jenkins

Theses

With the advent of smart phone technologies, the healthcare industry finds it challenging to keep up with technology demands. In the medical domain, patients are experiencing longer wait times for medical treatment. A basis of dissatisfaction with healthcare, often observed by patients, is the amount of time they wait during a visit. The wait times have a greater delay within medical emergency facilities. Current medical wait time applications may encourage patients to be seen quickly but does not necessarily offer quality care or other aspects of their visits. The amount of time a patient experiences in an emergency facility could …

Thermal Characterization Of As4/3501-6 Carbon-Epoxy Composite, Bradley R. Doleman

Theses

Thermal diffusivity, specific heat, and thermal conductivity are important thermophysical properties of composite materials and foams. Thermal characterization provides these material properties which play a significant role in the engineering design process of space systems, aerospace vehicles, transportation, energy storage devices, and power generation including fuel cells. Thermal conductivity is the parameter that is important in problems involving heat transfer and thermal structures. Because it determines the working temperature levels of a material, the thermal conductivity is critical when considering the performance of materials in high temperature applications as well as safety, process control, and quality assurance. As a result …

Prophage Proximities To Cell Boundary Genes And Other Functional Categories In Escherichia Coli Genomes, Corey D. Young

Theses

Changes in bacterial genomes due to the integration of prophages have been proposed to be part of a symbiotic relationship. Prophage activity is common for bacterial pathogens in the fluctuating environment of animal hosts. Pathogenic bacteria have been found to have extensive variation of their bacterial cell boundary zone of components, which is the inherent interface for virulence properties of antigenicity, toxicity, and resistance. Prophages are a source of this variation, both through insertion of cargo genes via prophages into bacterial strains, and additional effects due to prophage insertions affecting the overall genomic structure. The latter scenario of genomic reorganization …

Monitoring Wear In Sliding Surfaces By Using Acoustic Emission Signals, A.B.M. Iftekharul Islam

Theses

Machine parts that are in relative motion often face a state of friction in their applications. The friction, when it is uncontrolled, can cause the machine part surfaces to degrade severely. At the time of service of a machine, relative motion between surfaces sometimes can cause crack growth of fretting fatigue. Conventional methods for determining the degree of deterioration and potential crack growth formation in in-situ application have not been proven sufficiently effective. Acoustic emission (AE) based Structural Health Monitoring (SHM) has the potential for real-time detection of damage growth in structures. But in the case of sliding contact between …

Are We Sick Yet: Assessing Consumer Mortality From Food Contamination In Multiple Distribution Channels, Raquel T. Teasley

Theses

According to the Center for Disease Control approximately 48 million people get sick from food-borne illnesses per year. In 2011, about 80% of illnesses were triggered by unspecified agents transmitted through food. Food contaminations put customers at risk and can be detrimental to the economy since customers rely on the fact that the food system is reliable and resilient. This research aims to compare the vulnerabilities of three food supply chain distribution channels: food retail, food service and food manufacturing. Distribution channels are the last nodes in the supply chain and they dictate how many people interact with contaminated products. …

Combining High Speed Imaging And Acoustic Emission Analysis For Crack Growth In Thick Samples, Jr. Michael Gillespie

Theses

Over 80% of components in a system that undergo fatigue cycling fail due to cracking. Acoustic emission (AE) has become a major resource in non-destructive testing (NDT) for the detection, location, and quantification of cracking events. Normally, AE an event is referred to as crack growth, fretting, or friction. As an AE signal progress through material, the waveform converts into several modes; additionally, attenuation and dispersion may also change the waveform. Furthermore, the noise may intrude into the signal in such a way that by time the signal from the source arrives at the sensor the waveform becomes very complex. …

Investigation Of Drinking Water/Beverage Contaminants Within The Beverage Industry, Elizabeth Hobbs

Theses

The impact of water resource quality has influenced the community worldwide. It is an on-going target for water suppliers to produce suitable drinking water and the beverage industry to provide suitable water for the production of beverages. This diligence will ensure the consumer is provided with a product safe for consumption. The research and analytical techniques explored in this thesis may be of benefit to the beverage industry for the monitoring of inorganic contaminants present in water and carbonated soft drinks. The occurrence of certain contaminants in drinking water has become a major issue in the water industry in recent …

Investigation Into The Measure, Correlate And Predict Methodologies Used In Wind Farm Design Software, Brendan O'Sullivan

Theses

This paper is focused on the Measure Correlate and Predict (MCP) methodologies used to estimate long term wind resource at a prospective site. The first common step in all MCP methodologies is a successful wind measurement campaign at the prospective site. This campaign involves the erection of a wind measurement mast (ideally to the hub height of the proposed turbine) and careful selection of booms, mountings and anemometers. The wind measurement campaign is a vital part of the process as the correlation and prediction analysis is only as accurate as the measured wind data. Correlation is a measure of the …

Role Of Surface Topology On Wetting Of Complex Surfaces, Javier Sanchez Santiago

Theses

Wetting and capillary phenomena are important components of chemical engineering processes. Most if not all wetting and capillary phenomena can be explained based on three fundamental tools: (1) the Young-Laplace equation describing curvature of interfaces, (2) the static contact angle relating macroscopic measurements to molecular forces and (3) the effect of solid surface microstructures on interfaces near the three-phase contact line. To understand the role of surface microstructure this thesis revisited a series of experiments started by Brook Taylor and reported by Francis Hauksbee (1712) more than 300 years ago on capillary rise between glass planes forming a narrow wedge …

Numerical Modeling Of Polyurea Coated Cementitious Materials For Flexure And Impact Loads, Naga Deepika Pothula

Theses

The research focuses on predicting the mechanical properties of various cementitious based materials coated with polyurea using the finite element program ABAQUS. To determine the effect of the polyurea coated systems, simple finite element analyses are performed on the beam model for flexure and the concrete slab model for impact. The experimental results carried out by Hyungjoo Choi [1, 2] are used to validate the model and to study the effect of the coating conditions of polyurea (plain, top, bottom, both). The load-displacement curves are plotted. Results show that using polyurea coating increases of deflection and load at failure (ductility), …

Controlling A Boost Dc/Dc Converter For Led Array Using Super Twisting Feedback Algorithm, Steve Mays

Theses

LEDs are nonlinear P-N junction devices that are powered in series connected arrays from controlled DC-DC converters. To develop sufficient voltage to power the LEDs and follow an external command signal, a voltage boosting converter is used. There are three challenges preventing a boost converter from being able to track a command signal: the internal dynamics of a boost converter are unstable, the boost converter components values can vary, and the LED load is very nonlinear. To control the unstable boost converter, a super twisting control is introduced in concert with dynamic sliding manifold approach, designed, and tested. Via simulations, …

Hypersonic Missile Control In Terminal Mode Using Continuous Higher Order Sliding Mode Control Driven By Disturbance Observer, Polk Yu

Theses

The objective of this thesis investigate terminal phase optimal trajectory control of a hypersonic missile through the use of a higher order sliding mode control technique. The higher order sliding mode control algorithm considered utilizes a continuous finite time convergent controller that is driven by a higher order siding mode disturbance observer. The proposed higher order sliding mode control technique has been validated via simulations and demonstrated high robustness and accuracy of the output tracking in the presence of the matched and unmatched external disturbances and the missile model uncertainties.

Analysis Of Stress Waves Generated During Normal And Oblique Impacts On Aerospace Panels, Gopal Kumaran

Theses

Foreign object impact on aircraft structures is a critical event that can affect the structural integrity and compromise the safety of the aircraft. The aerospace industry devotes a considerable amount of effort to detect impact damage. The real time impact detection and quantification system can improve safety and reduce operation cost. In order to identify the impact damage, it becomes necessary to study the impact location and force history. There are a number of studies on this topic which focus on obtaining an approximate representation of force history in damage events. However, a number of important aspects of foreign object …

Under A Pale Grey Sky: An Interactive Timeline Of Iroquoian Warfare And Its Impact On The Acceleration Of American Colonization, Thomas Weaver

Theses

Early American settlers thought the Iroquois to be a violent, forceful and barbaric amalgamation of Native American Nations. Their organization of warfare, community, and politics allowed them to remain one of the most powerful nations for many years. Conflict with other tribes was a normal part of life for the Iroquois and the surrounding nations. However, as the American settlers began moving towards the frontier, Iroquois conflicts with the Algonquian begin to rise in frequency. This led to weakening of the Iroquois population and allowed the American settlers to usurp land from the Six Nations without considerable opposition.

Determining A New Alignment Scoring Matrix For Disordered Proteins, Adam Handen

Theses

Intrinsically disordered proteins (IDPs) are polypeptide sequences that do not form a rigid three dimensional structure when isolated in the cytosol of the cell. These sequences are very common in most genomes, and usually are involved in many protein-protein interactions. IDPs also play a key role in many diseases, including cancer and Huntington's disease. However, IDPs are difficult to study because of their amorphous shape, high mutation rate, and unique amino acid composition. These obstacles make homology studies especially difficult.

This study focused on generating a new substitution matrix designed to aid in homology studies of IDPs. The matrix was …

Ultrafast Carrier Dynamics In Semiconductor Nanostructures, Jaroslaw Pulka

Theses

Rapid development of telecommunication systems forces a switch to all- optical data processing and transmission. To design such systems it is critical to understand the ultrafast processes which occur in the components of such systems, especially in Monolithic Modelocked Lasers. The purpose of this work was to identify the main physical processes influencing carrier dynamics in semiconductor nanostructures which show promise for future telecommunication systems. This study was carried out by means of ultrafast pump-probe spectroscopy, which allowed characterisation with a sub-picosecond resolution. The main part of the thesis concentrates on the analysis of the InAs/GaAs Quantum Dot (QD) system. …

How Minority Sporting Organisations In Ireland Are Promoting And Growing Their Sports Using Social Media: A Public Relations Perspective., Peter Lucey

Theses

The aim of this research study was to explore how minority sports organisations in Ireland are using social media to effectively grow and promote their sport. The researcher has analysed how these organisations are currently making use of social media and how it has benefited them in their operations. Relevant secondary literature was studied in depth along with the primary research methods that were used for this study. The research methodology used by the researcher constituted elements of both quantitative and qualitative analyses. Interviews and questionnaires made up the main research tools in addition to an action research approach as …

Improving Usability: Evaluating The Effect Of Changing Environmental Factors On Cognitive Load, Robin J. Deegan

Theses

Mobile devices are now truly ubiquitous. Their pervasiveness in all facets of our lives brings many advantages. Principle to these advantages is the notion that mobile devices can be used “Anytime, Anywhere”. The size, portability, battery life and computational power of mobile devices mean that they can be used for a diverse range of uses in an equally diverse range of environments.

Usability is primarily concerned with “ease of use” and “learnability”. Mobile devices are challenging this notion of Usability as they are used in new ways. Firstly mobile devices arc used in complex distracting environments and these distractions interfere …

Optical Emission Properties Of Band Structure Tailored Semiconductor Nanostructures, Nicola Pavarelli

Theses

In the past decades, with the development of low-dimensional semiconductor heterostructures, research has been focused on studying novel materials and proposing new solutions for the improvement and optimization of numerous optoelectronic applications. Examples of these applications include optical data storage, displays and medical diagnostics in the ultraviolet and visible spectral range, or telecommunication networks, solar cells, gas sensing and imaging systems in the near- and mid-infrared. In this thesis, the optical characterization of a number of promising semiconductor nanostructures for the realization of next-generation optoelectronic devices is reported. The optical emission properties of each structure, measured by means of power-dependent …

Circuit Solutions To Compensate For Device Degradation In Analog Design In Scaled Technologies, Mark Pude

Theses

The continued aggressive scaling of semiconductor devices has had detrimental effects on the performance of those devices as used in analog circuitry. Specifically, the maximum intrinsic gain (MIG) of the devices continues to degrade as the device channel lengths are reduced below 100 nm and beyond. MIG is shown to degrade from 21.6 dB in a 180 nm technology to 12.2 dB in a 65 nm technology despite the application of traditional design techniques including device size scaling and bias voltage increases. This reduction in MIG along with other process scaling effects significantly complicates the design of linear amplifiers in …

Evaluation, Adaptation And Validation Of A Model To Predict Grass Growth In Ireland, Christina Hurtado Uria

Theses

Budgeting grass supply allows producers to minimise the quantity of purchased feed required in the diet of grazing livestock. One tool for managing grass supply could be a mathematical model that can simulate grass growth. The development of such a model would allow better management around the variability of feed supply and help identify feed surpluses and deficits, and therefore increase the accuracy of management decisions. This would be a key feature of profitable milk and meat production systems in the future which will be hugely important as global food demand increases due to population growth. It is forecasted that …

The Death Of The Press Release And The Changing Media Relations Landscape: A Public Relations Perspective, Jenn Crotty

Theses

The public relations industry of today is a much different one to that of a decade ago. The changes that are taking place within the public relations industry are monumental and are not going unnoticed. In recent years the explosion of new media and social networks has led to a distorted media relations landscape. Many academics and public relations professionals have began to focus on the importance of incorporating new media and social networks into their occupation. It appears as though the traditional media landscape is being swept under the rug.

This study aims to challenge the perception that new …