Physical Sciences and Mathematics Commons^™

Effect Of Reworking And Bioturbation On Sedimentary Reactive Iron Within A Microtidal Estuary, Amy Kathleen Pitts

OES Theses and Dissertations

Mixed redox conditions in sediments due to physical reworking may allow for enhanced remineralization of refractory organic matter due to Fe(III) redox cycling. In part this may occur because easily reducible iron oxides can be used by heterotrophic bacteria to remineralize the organic carbon. This phenomena has been observed in bioturbated sediments and in areas where physical factors (such as strong bottom currents) constantly rework the sediments. To specifically determine the effects of physical reworking and bioturbation on concentrations of easily reducible iron oxides, reactive iron concentrations were measured in surface sediments taken from two contrasting sites in the York …

Circulation Of The Western Antarctic Peninsula: Implications For Biological Production, Maria Andrea Piñones Valenzuela

OES Theses and Dissertations

The western Antarctic Peninsula (wAP) continental shelf is characterized by large persistent populations of Antarctic krill ( Enphausia superba) and by regions of enhanced concentrations of marine mammals and other predators (hot spots). This study focused on understanding the role of ocean circulation in providing retention/connectivity of wAP Antarctic krill populations and in maintaining biological hot spot regions. Numerical Lagrangian particle tracking simulations obtained from the Regional Ocean Modeling System (ROMS) configured for the wAP region provided quantitative estimates of retention, immigration and emigration from the wAP continental shelf. Additional simulations with a one-dimensional temperature-dependent growth model for krill …

A Google Earth-Based Framework For Visualization Of The Chesapeake Bay Operational Forecast System, Gary Lawson

Computational Modeling & Simulation Engineering Theses & Dissertations

For the persons who live near and travel the waters of the Chesapeake Bay, the data provided by the Chesapeake Bay Operational Forecast System (CBOFS) is invaluable. The information provided includes measurements and forecasts of surface wind velocity, water current velocity, salinity levels, water level, and temperature. Currently, this information is freely available on the CBQ_FS website hosted by the National Oceanographic and Atmospheric Administration (NOAA). It is offered as Nowcast, measured data, and Forecast data and is visualized using 2D images which describe a subset of the data in an easy to read chart. However, if the data were …

Controls On The Formation Of Algal Blooms In The Lower Chesapeake Bay And Its Tributaries, Ryan Eric Morse

OES Theses and Dissertations

Algal blooms occur seasonally in the Chesapeake Bay and its tributaries, and while the consequences of algal blooms have been qualitatively and quantitatively assessed, the causes of algal blooms and mechanisms of bloom initiation are still not well understood despite decades of research. In order to understand nutrient dynamics and other factors that promote the initiation of algal blooms, the Lafayette River, a tidal sub-estuary of Chesapeake Bay that experiences seasonal algal blooms, was sampled daily in the fall of 2005. Three phytoplankton blooms (Chlorophyll a concentrations exceeding twice the average of monthly measurements from 2000-2009) occurred during this period, …

Automatic High-Fidelity 3d Road Network Modeling, Jie Wang

Computational Modeling & Simulation Engineering Theses & Dissertations

Many computer applications such as racing games and driving simulations frequently make use of 3D high-fidelity road network models for a variety of purposes. However, there are very few existing methods for automatic generation of 3D realistic road networks, especially for those in the real world. On the other hand, vast road network GIS data have been collected in the past and used by a wide range of applications, such as navigation and evaluation. A method that can automatically produce 3D high-fidelity road network models from 2D real road GIS data will significantly reduce both the labor and time needed …

The Nature, Origin And Preservation Of Amide Organic Nitrogen In Organic Matter, Georgina Anne Mckee

Chemistry & Biochemistry Theses & Dissertations

Past studies have found much of nonliving sedimentary/aqueous nitrogen-containing organic matter (NCOM) is composed of amides, assumed to be peptides/proteins. Their lability calls into question their survival, and several hypotheses have been suggested to explain this. Using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and nuclear magnetic resonance (NMR) spectroscopy I investigated the molecular amide composition in sedimentary/aqueous systems while reassessing their preservation and formation routes.

Development of a suitable methodology is essential for successful NCOM study due to electrospray ionisation source requirements: sediment samples need to be rendered into solution. Based on NMR and FT-ICR-MS analysis, I determined …

Improving The Efficiency Of Organic Solar Cells By Varying The Material Concentration In The Photoactive Layer, Kevin Anthony Latimer

Electrical & Computer Engineering Theses & Dissertations

Polymer-fullerene bulk heterojunction solar cells have been a rapidly improving technology over the past decade. To further improve the relatively low energy conversion efficiencies of these solar cells, several modifications need to be made to the overall device structure. Emerging technologies include cells that are fabricated with interfacial layers to facilitate charge transport, and tandem structures are being introduced to harness the absorption spectrum of polymers with varying bandgap energies.

When new structures are implemented, each layer of the cell must be optimized in order for the entire device to function efficiently. The most volatile layer of these devices is …

Excitation-Induced Ge Quantum Dot Growth On Si(100)-2x1 By Pulsed Laser Deposition, Ali Oguz Er

Physics Theses & Dissertations

Self-assembled Ge quantum dots (QD) are grown on Si(100)-(2×1) with laser excitation during growth processes by pulsed laser deposition (PLD). In situ reflection-high energy electron diffraction (RHEED) and post-deposition atomic force microscopy (AFM) are used to study the growth dynamics and morphology of the QDs. A Q-switched Nd:YAG laser (λ = 1064 nm, 40 ns pulse width, 5 J/cm² fluence, and 10 Hz repetition rate) were used to ablate germanium and irradiate the silicon substrate. Ge QD formation on Si(100)-(2×1) with different substrate temperatures and excitation laser energy densities was studied. The excitation laser reduces the epitaxial growth temperature …

Using The Web Infrastructure For Real Time Recovery Of Missing Web Pages, Martin Klein

Computer Science Theses & Dissertations

Given the dynamic nature of the World Wide Web, missing web pages, or "404 Page not Found" responses, are part of our web browsing experience. It is our intuition that information on the web is rarely completely lost, it is just missing. In whole or in part, content often moves from one URI to another and hence it just needs to be (re-)discovered. We evaluate several methods for a \justin- time" approach to web page preservation. We investigate the suitability of lexical signatures and web page titles to rediscover missing content. It is understood that web pages change over time …

A Framework For Dynamic Traffic Monitoring Using Vehicular Ad-Hoc Networks, Mohammad Hadi Arbabi

Computer Science Theses & Dissertations

Traffic management centers (TMCs) need high-quality data regarding the status of roadways for monitoring and delivering up-to-date traffic conditions to the traveling public. Currently this data is measured at static points on the roadway using technologies that have significant maintenance requirements. To obtain an accurate picture of traffic on any road section at any time requires a real-time probe of vehicles traveling in that section. We envision a near-term future where network communication devices are commonly included in new vehicles. These devices will allow vehicles to form vehicular networks allowing communication among themselves, other vehicles, and roadside units (RSUs) to …

Effects Of 11 Years Of Co2 Enrichment On Root Biomass And Spatial Distribution In A Florida Scrub-Oak Ecosystem, Rachel Eilenfield Schroeder

Biological Sciences Theses & Dissertations

A Florida (USA) scrub-oak ecosystem was exposed to elevated atmospheric CO₂ in open-top chambers from 1996-2007. Minirhizotrons and ground-penetrating radar (GPR) were used to measure fine root (< 2 mm diameter) and coarse root (> 5 mm diameter) biomass, respectively. After 11 years of CO₂ enrichment, there was a trend of greater total root biomass under elevated CO₂. Fine root biomass exhibited a pattern of recovery and steady state throughout the study, with significant CO₂ stimulation observed only after disturbance. Greater root biomass under elevated CO₂ during recovery periods could result in greater carbon inputs belowground, alteration of the soil carbon …

Perfectly Matched Layer Absorbing Boundary Conditions For The Discrete Velocity Boltzmann-Bgk Equation, Elena Craig

Mathematics & Statistics Theses & Dissertations

Perfectly Matched Layer (PML) absorbing boundary conditions were first proposed by Berenger in 1994 for the Maxwell's equations of electromagnetics. Since Hu first applied the method to Euler's equations in 1996, progress made in the application of PML to Computational Aeroacoustics (CAA) includes linearized Euler equations with non-uniform mean flow, non-linear Euler equations, flows with an arbitrary mean flow direction, and non-linear clavier-Stokes equations. Although Boltzmann-BGK methods have appeared in the literature and have been shown capable of simulating aeroacoustics phenomena, very little has been done to develop absorbing boundary conditions for these methods. The purpose of this work was …

Insights Into Chemical Structure Changes Of Kerogen From Bituminous Coal In Response To Dike Intrusions Investigated By Advanced Solid-State 13C Nmr, Yuan Li

Chemistry & Biochemistry Theses & Dissertations

Variations in the chemical structures of kerogens From highly volatile bituminous coal located near two igneous dike intrusions in the Illinois Basin were examined in detail by advanced solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Spectral-editing techniques were used to identify specific functional groups. Direct polarization was used to quantify different functional groups. ¹H-¹³C two- dimensional heteronuclear NMR was used to examine connectivities and proximities, and ¹H-¹³C long-range recoupled dipolar dephasing was used to estimate aromatic cluster sizes. With decreasing distance to dike contacts and increasing thermal maturity (vitrinite reflectance R₀ from …

Model-Based Analyses Of Nitrogen On The Mid-Atlantic Bight Continental Shelf, Tian Tian

OES Theses and Dissertations

The biogeochemistry of continental shelf systems is an important, but poorly quantified, component of the global cycling of nitrogen and carbon. In this study, simulations obtained from a one-dimensional (ID) biogeochemical model developed for the Middle Atlantic Bight (MAB) portion of the U.S. eastern continental shelf were analyzed to investigate nitrogen cycling processes. The 1D model included lower trophic level interactions and was forced by advective fields obtained from a corresponding three-dimensional biogeochemical model. Taylor and target diagram analyses, which compared in situ measurements of sea surface temperature (SST) and salinity, and chlorophyll and particulate organic carbon (POC) derived from …

The Effect Of An Offshore Wind Turbine Array On Circulation In An Idealized Coastal Ocean, Mahmoud Kamel

OES Theses and Dissertations

The effect of arrays of wind turbines on circulation in the coastal ocean is analyzed with a coastal numerical model applied to a shallow coastal area like the Mid Atlantic Bight (MAB). A simplified model domain is specified with a linearly deepening shelf along a straight coastline. The initial density structure is a quasi-two layer situation with a sharp thermocline. Wind stress in most of the cases is either upwelling or downwelling favorable with constant amplitude continuing after a smooth start. There are two cases where oscillating wind forcing is used. Simulations consider wind arrays having different widths, different locations …

Population Dynamics Of Sheepshead (Archosargus Probatocephalus; Walbaum 1792) In The Chesapeake Bay Region: A Comparison To Other Areas And An Assessment Of Their Current Status, Joseph Charles Ballenger

OES Theses and Dissertations

Sheepshead recently have seen an increase in fishing pressure in Virginian waters of the Chesapeake Bay. This increase in fishing pressure has led to demands to install effective management measures to protect the fishery. However, no study regarding the population dynamics, and thus potential yield, of sheepshead has been conducted north of Cape Hatteras. We addressed the need for information regarding the population dynamics of Chesapeake Bay sheepshead by investigating their age distribution, growth rate and reproductive biology. We used this information to construct yield-per-recruit models, which local management agencies may use in the formation of scientifically based management measures. …

A Least Squares Closure Approximation For Liquid Crystalline Polymers, Traci Ann Sievenpiper

Mathematics & Statistics Theses & Dissertations

An introduction to existing closure schemes for the Doi-Hess kinetic theory of liquid crystalline polymers is provided. A new closure scheme is devised based on a least squares fit of a linear combination of the Doi, Tsuji-Rey, Hinch-Leal I, and Hinch-Leal II closure schemes. The orientation tensor and rate-of-strain tensor are fit separately using data generated from the kinetic solution of the Smoluchowski equation. The known behavior of the kinetic solution and existing closure schemes at equilibrium is compared with that of the new closure scheme. The performance of the proposed closure scheme in simple shear flow for a variety …

A Penalty-Based Approach To Handling Cluster Sizing In Mobile Ad Hoc Networks, Ryan Florin

Computer Science Theses & Dissertations

In Mobile Ad Hoc Networks (MANETs) nodes are allowed to move freely which causes instability in the network. To handle this, the nodes are grouped into clusters which make the topology of the network appear more stable. In proposed algorithms, the size of these clusters has been either ignored or handled insufficiently. This Thesis proposes a penalty-based approach to handle cluster sizing in a more appropriate manner. A configurable penalty function is defined which assigns penalties to each of the possible cluster sizes. The penalty is then used in conjunction with a merge qualifier to determine if a merge is …

A Probabilistic Analysis Of Misparking In Reservation Based Parking Garages, Vikas G. Ashok

Computer Science Theses & Dissertations

Parking in major cities is an expensive and annoying affair, the reason ascribed to the limited availability of parking space. Modern parking garages provide parking reservation facility, thereby ensuring availability to prospective customers. Misparking in such reservation based parking garages creates confusion and aggravates driver frustration. The general conception about misparking is that it tends to completely cripple the normal functioning of the system leading to chaos and confusion. A single mispark tends to have a ripple effect and therefore spawns a chain of misparks. The chain terminates when the last mispark occurs at the parking slot reserved by the …

Examination Timetabling With Mathematical Programming An Application In Turkish Air Force Academy, Emrah Koksalmis

Engineering Management & Systems Engineering Theses & Dissertations

The focus of this thesis is the educational timetabling problem, which is a very challenging problem to solve especially with a high number of the departments, branches, classes, and students. Due to the large scale of educational timetabling problems and preferences of the stakeholders, it is almost impossible to form a general model that solves all of the timetabling problems in the literature. This resulted in the need to develop and employ specific models for specific institutions.

The purpose of this study is to develop a mathematical programming model that solves the examination timetabling problem in Turkish Air Force Academy …

Data Aggregation And Dissemination In Vehicular Ad-Hoc Networks, Khaled Ibrahim

Computer Science Theses & Dissertations

Vehicular Ad-Hoc Networks (VANETs) are a fast growing technology that many governments and automobile manufacturers are investing in to provide not only safer and more secure roads, but also informational and entertainment-based applications for drivers. The applications developed for VANETs can be classified into multiple categories (safety, informational, entertainment). Most VANET applications, regardless of their category, depend on having certain vehicular data(vehicular speed, X position and Y position) available. Although these applications appear to use the same vehicular data, the characteristics of this data (i.e., amount, accuracy, and update rate) will vary based on the application category. For …

Adding Executable Context To Executable Architectures: Enabling An Executable Context Simulation Framework (Ecsf), Johnny J. Garcia

Computational Modeling & Simulation Engineering Theses & Dissertations

A system that does not stand alone is represented by a complex entity of component combinations that interact with each other to execute a function. In today's interconnected world, systems integrate with other systems - called a system-of-systems infrastructure: a network of interrelated systems that can often exhibit both predictable and unpredictable behavior. The current state-of-the-art evaluation process of these system-of-systems and their community of practitioners in the academic community are limited to static methods focused on defining who is doing what and where. However, to answer the questions of why and how a system operates within complex systems-of-systems interrelationships, …

Computational Investigation Of The Bioactive Selenium Compounds Ebselen And Selenious Acid, Sonia Antony

Chemistry & Biochemistry Theses & Dissertations

Selenium, a toxic element, is required in trace quantities for the proper functioning of biological systems. The experimental mechanistic study of the reactions of ebselen and selenious acid is difficult due to complexity of the reaction mixtures and the presence of short-lived intermediates. Computational modeling of the reactivity of these species can give us an insight into their mechanisms, but the process is complicated by proton exchanges associated with the mechanistic steps. In gas phase modeling, this may be corrected to a certain level using the solvent assisted proton exchange (SAPE) method. SAPE is a modeling technique that mimics solvent …

Characterizations Of Atmospheric Pressure Low Temperature Plasma Jets And Their Applications, Erdinc Karakas

Electrical & Computer Engineering Theses & Dissertations

Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a …

Incorporating Physical Fitness Through Rushing Can Significantly Affect Tactical Infantry Simulation Results, Elaine Marie Smith Blount

Computational Modeling & Simulation Engineering Theses & Dissertations

Physical fitness is accepted as an influence on the outcome on the battlefield; yet, research indicates that it has not been incorporated into tactical infantry simulations. Including physical capabilities may have a significant impact upon the results of a tactical simulation. Several battlefield tasks were reviewed, and rushing was selected to implement in tactical infantry simulations. A preliminary spreadsheet model was created that indicated rushing velocity would impact a tactical simulation. Two tactical infantry simulations were created: a helicopter extraction scenario where 13 soldiers rushed to extraction site while two enemies were shooting and a rushing scenario that consisted of …

A Framework For Incident Detection And Notification In Vehicular Ad-Hoc Networks, Mahmoud Abuelela

Computer Science Theses & Dissertations

The US Department of Transportation (US-DOT) estimates that over half of all congestion events are caused by highway incidents rather than by rush-hour traffic in big cities. The US-DOT also notes that in a single year, congested highways due to traffic incidents cost over $75 billion in lost worker productivity and over 8.4 billion gallons of fuel. Further, the National Highway Traffic Safety Administration (NHTSA) indicates that congested roads are one of the leading causes of traffic accidents, and in 2005 an average of 119 persons died each day in motor vehicle accidents.

Recently, Vehicular Ad-hoc Networks (VANET) employing a …

Triple Coincidence Beam Spin Asymmetry Measurements In Deeply Virtual Compton Scattering, Mustafa Canan

Physics Theses & Dissertations

The Generalized Parton Distributions (GPDs) provides hitherto the most complete information about the quark structure of hadron. GPDs are accessible through hard-exclusive reactions, among which Deeply Virtual Compton Scattering (DVCS) is the cleanest reaction. A dedicated DVCS experiment on Hydrogen (E00-110) ran in the Hall A at Jefferson Laboratory in Fall 2004. I present here Beam Spin Asymmetry (BSA) results for the ep → epγ reaction studied in the E00-110 experiment with fully exclusive triple coincidence H(e, e'γp ) detection. I present a re-calibration of the electromagnetic calorimeter used to detect the high energy photon. This calibration …

Epistemic Strategies For Solving Two-Dimensional Physics Problems, Mary Elyse Hing-Hickman

Physics Theses & Dissertations

An epistemic strategy is one in which a person takes a piece of knowledge and uses it to create new knowledge. Students in algebra and calculus based physics courses use epistemic strategies to solve physics problems. It is important to map how students use these epistemic strategies to solve physics problems in order to provide insight into the problem solving process.

In this thesis three questions were addressed: (1) What epistemic strategies do students use when solving two-dimensional physics problems that require vector algebra? (2) Do vector preconceptions in kinematics and Newtonian mechanics hinder a student's ability to apply the …

Spatially-Explicit Agent-Based Modeling Of Ecosystem Change And Epizootiological Impacts On Caribbean Spiny Lobster, Panulirus Argus, Thomas William Dolan Iii

Biological Sciences Theses & Dissertations

Agent-based models explicitly incorporate interactions and variation at the individual level, just as in the real world. As a result, agent-based models are realistic, intuitive, and generally less complex mathematically than their analytical counterparts. Their primary disadvantage is the large amount of detailed data required to construct and parameterize them. Although the use of agent-based simulation is increasing in ecology, they are highly specific, so are rarely used for development of theory. To demonstrate the flexibility and utility of this approach I developed a multi-species, agent-based, spatially-explicit model of the spiny lobster nursery of southern Florida that incorporates changing salinities, …

Fusion Of Visual And Thermal Images Using Genetic Algorithms, Sertan Erkanli

Electrical & Computer Engineering Theses & Dissertations

Demands for reliable person identification systems have increased significantly due to highly security risks in our daily life. Recently, person identification systems are built upon the biometrics techniques such as face recognition. Although face recognition systems have reached a certain level of maturity, their accomplishments in practical applications are restricted by some challenges, such as illumination variations. Current visual face recognition systems perform relatively well under controlled illumination conditions while thermal face recognition systems are more advantageous for detecting disguised faces or when there is no illumination control. A hybrid system utilizing both visual and thermal images for face recognition …