Physical Sciences and Mathematics Commons^™

Spatial And Temporal Variability Of Particulate And Chromophoric Dissolved Organic Matter Absorption In The Northern Gulf Of Mexico, Ashley Ann Lojek

Master's Theses

Coastal regions influenced by large freshwater inputs exhibit large variability in absorption and associated optical properties. Therefore, understanding coastal ecosystem processes requires intensive, ongoing sampling. Analysis of the Mississippi and Atchafalaya River plumes took place on board the RIV Pelican on two separate cruises. MagMix-1 occurred from May 1 to May 8, 2008 and corresponded to the highest discharge periods for both rivers for 2008; MagMix-11 took place October 31 to November 6, 2008 and corresponded to the lowest discharge periods for both rivers for 2008. Samples were collected along four transects in the northern Gulf of Mexico and were …

Factors Influencing The Spatial And Temporal Distrubtion Of Primary Productivity And Community Respiration In The Mississippi Coastal Estuarine Region, Ryan Anthony Vandermeulen

Master's Theses

This study describes the spatial and temporal distribution of net primary productivity (NetPP) and respiration (RESP) in relation to the biogeochemical, optical, and hydrographic variability in the Mississippi Sound and Mississippi Bight over the course of one year. Surface in-situ measurements of NetPP and RESP were regularly determined at two stations by a time-course detection of dissolved oxygen (DO) using novel optode technology. In addition, various biogeochemical, optical, and hydrographic parameters were examined over 14 stations throughout the estuary over a year, using ground and satellite (MODIS Aqua) measurements. In this study, consistently low dissolved inorganic N:P ratios (average N:P …

Understanding Corrosion Protection And Failure Through Model Polymers In Thin Films, Joshua Smith Hanna

Dissertations

When developing a model polymeric system to facilitate in the detection of molecular and microscopic events that preface macroscopic corrosive failure; a better understanding of how polymers can indicate corrosion was accomplished. Initially, the thought that molecular chain scission as a necessity for corrosion to occur had to be tested. Through the utilization of high molecular weight thermoplastic (HMWTP) model polymers, it was found that corrosion protection did not correlate to the quantity of weak bonds within an epoxy-amine polymer matrix. Therefore more sensitive methods of detecting corrosion had to be developed since changes within the polymer matrix did not …

Polymer Surface Engineering Via Thiol-Mediated Reactions, Ryan Matthew Hensarling

Dissertations

Synthesis of polymer brushes to decorate a surface with desired functionality typically involves surface-initiated polymerization (SIP) of functional, but non-reactive monomers. This approach suffers major drawbacks associated with synthesizing sufficiently thick polymer brushes containing surface-attached polymer chains of high molecular weight at high grafting density (i.e. cost, synthetic effort and functional group intolerance during polymerization). The research herein seeks to circumvent these limitations by the decoration of surfaces with polymer chains bearing specific pendent functional groups amenable to post-polymerization modification (PPM). In particular, this dissertation leverages PPM via a specific class of click reactions – thiol-click – that 1) enables …

A Time Series Analysis Method Using Hidden Variables For Gene Network Reconstruction, Xi Wu

Dissertations

The DNA microarray technology can be applied to obtain time series data which contains thousands of genes and tens of time points. When confront the great amount of data points a fast and effective method must be constructed to extract useful information. The assumption that the interactions between genes are static in the time series data is made. After made the assumption how to reconstruct those interactions becomes a difficulty problem. Since the underlying interactions between genes are complicated, which involve transcription, translation and protein-protein interaction, to construct a model from physicochemistry is almost impossible/effortless. The popular methods constructed from …

Reification: A Process To Configure Java Realtime Processors, John Huddleston Heath

Dissertations

Real-time systems require stringent requirements both on the processor and the software application. The primary concern is speed and the predictability of execution times. In all real-time applications the developer must identify and calculate the worst case execution times (WCET) of their software. In almost all cases the processor design complexity impacts the analysis when calculating the WCET. Design features which impact this analysis include cache and instruction pipelining. With both cache and pipelining the time taken for a particular instruction can vary depending on cache and pipeline contents. When calculating the WCET the developer must ignore the speed advantages …

Microstructure, Vacancies And Voids In Hydrogenated Amorphous Silicon, Rajendra Timilsina

Dissertations

This dissertation presents a theoretical and computational study of microstructure, vacancies and voids in hydrogenated amorphous silicon (a-Si:H). The microstructure consists of all possible silicon-hydrogen bonding configurations such as SiH, SiH₂, SiH₃ and SiH₄. However, it is highly dominated (approximately 75% or even more) by monohydride (SiH) configurations. Furthermore, the hydrogen atoms locate in both clustered and diluted phases; as a result, the distribution becomes highly inhomogeneous. Approximately 5% of hydrogen atoms reside in a form of isolated monohydrides at the lower (7 at.%) concentration whereas such configurations do not appear at the higher concentrations …

Producing Data To Support The Detection And Understanding Of Early On-Set Corrosion In Accelerated Weathering, Stephanie Suzanne Messer

Master's Theses

The goal of the research reported herein was to generate data towards the development of methods and protocols for detecting, quantifying, and understanding early on-set corrosion events on and above aluminum 2024-T3. The studies focused on incorporating two main fluorescent probes into a few model epoxy and/or urethane coatings to detect X and Y axis specific pH changes occurring upon and above the substrate during pre-macroscopic corrosion. The primary fluorophore used was fluorescein, a pH sensitive probe capable of detecting the changes, mainly increases in pH that accompanies aluminum corrosion. The second molecular probe, rhodamine B, was utilized to better …

The Effect Of Poss Modified Montmorillonite On Elastomer Nanocomposites, Elana Celeste Lewis

Master's Theses

The goal of this thesis was to define the structural factors that determine performance in clay/rubber nanocomposites when polyhedral oligomeric silsesquioxane (POSS) is used as a dispersant. POSS has been shown previously to enhance clay, metal oxides, and carbon nanotube dispersion in thermoplastics matrices, but their performance in rubber systems has not yet been explored. There is little fundamental understanding of how POSS interacts with clay and how these modified fillers react with rubber matrices. This thesis aims to develop a greater understanding of the mechanisms of POSS-clay modification through the examination of two different POSS-clay systems and their effect …

Opportunistic Random Media Access In Wlans, Chong Tang

Master's Theses

This thesis proposes a new medium access protocol for IEEE 802.11 wireless local area networks, which is called opp01tunistic medium access. The protocol changes the media access opportunities of nodes by adjusting the contention window dynamically according to the different bit rates. Thereby, the protocol can reduce collision and improve throughput significantly. The n·aditional IEEE 802.11 standards access channel with binary exponential back-off algorithm and all nodes choose the back-off interval from the same initial range. The new protocol in this thesis divides nodes as well as contention windows in proportion to data rate. It offers three methods to group …

Coastal Hurricane Damage Assessment Via Wavelet Transform Of Remotely Sensed Imagery, Ricky Carl Crowsey

Dissertations

This dissertation uses post storm imagery processed using wavelet transforms to investigate the capability of wavelet transform-based methods to classify post storm damage of residential areas. Five level Haar, Meyer, Symlets, and Coiflets wavelet transform decompositions of the post storm imagery are inputs to damage classification models of post hurricane and tornado damage. Hurricanes Ike, Rita, Katrina, and Ivan are examined as are the 2011 Joplin and Tuscaloosa tornadoes.

Wavelet transform-based classification methods yielded varying classification accuracies for the four hurricanes examined, ranging from 67 percent to 89 percent classification accuracy for classification models informed by samples from the storms …

Dnagents 3.0: Genetically Engineered Mobile Agents For A Dynamic Network Topology, John Bovatsek

Honors Theses

Mobile agents are a relatively new topic in the realm of computer science research. They are being researched throughout the world by many scientists in order to ascertain their viability in real world applications. They have many disadvantages that keep them from widespread adoption. With his graduate dissertation Genetically Engineered Intelligent Mobile Agents, Kackley opened a whole new area of this research by combining mobile agents with genetic algorithms. These algorithms model the natural process of evolution to evolve solutions for problems.

This thesis is part of a research group effort to expand on Kackley’s work in the Database …

Photoionization Cross Section Measurement Of Rb 5p3/2, Charles Young

Honors Theses

The photoionization of atoms is still an emerging field with a foundation in laboratories and journals, yet much in the field is unknown. Photoionization is the phenomenon of an incident photon on a gaseous atom causing the ejection of an electron, and therefore, the atom becomes an ion. The photoelectric effect is a similar but broader term dealing with atoms in all forms: solid, liquid, gas, and plasma. The photoelectric effect causes a current whenever light with a certain wavelength is shined on a metal. The wavelength that is needed to eject an electron is dependent on the atom(s) involved …

Effect Of Compactified Dimensions On The Ground State Energy Of The Hydrogen Atom, Floyd Maseda

Honors Theses

The three-dimensional Hydrogen atom has been explored extensively, and a wavefunction and energy expression can be found in closed form. Little work, however, has been done with higher-dimensional atoms. This discussion focuses on the effects of adding first one then two compactified dimensions to a Hydrogen atom. The metric of the 4-D Hydrogen atom is taken to be R3 × S1 while the 5-D metric is taken to be R3 × S2. We first determine the form of the Laplacian operator in each space and use it to find the respective atomic potentials. The variational method is used to determine …

A Comparison Of Van Hiele Levels And Final Exam Grades Of Students At The University Of Southern Mississippi, Cononiah Watson

Honors Theses

This research analyzed students final exam scores in a college mathematics class with geometric components and their van Hiele levels upon entering the class. After the class was completed, each student’s final exam grade was calculated. The researcher used a Spearman correlation to compare the two; the result was a correlation coefficient of 0.742. The researcher then reported that the results of the van Hiele test are a major component in predicting a student’s success in such a class.

Mode Water In The Sea Of Japan: A Study On The Reproducibility Of Mode Water In The Data-Assimilating Regional Navy Coastal Ocean Model, Lea Kristen Locke

Master's Theses

Mode water in the Sea of Japan (SOJ) is associated with anti-cyclonic eddies that form in the quasi-stationary meanders of the offshore Tsushima Warm Current. Previous work in this region has shown free-running, advanced ocean models are able to capture the physical processes that generate mode water; however, data assimilation is seen to ,I have a negative impact. A 3.5km resolution Regional Navy Coastal Ocean Model is used to assess the ability of a data-assimilating model to reproduce the mode water structure in the SOJ. The model's response to the assimilation of in-situ and synthetic profiles, derived from remotely sensed …

Comparison Of The Observed Mixe Layer Depth In The Lee Of The Hawaiian Island To The Modeled Mixed Layer Depth Of The Regional Navy Coastal Ocean Model, Jeffery Todd Rayburn

Master's Theses

Accurately modeling the depth of the surface mixed layer in the lee of the Hawaiian Islands is important to naval operations because the area hosts numerous training exercises. Providing an accurate picture of the environment aids naval operators in making important tactical decisions. This study evaluates the ability of the Hawaii Regional Navy Coastal Ocean Model to accurately predict the depth of the surface mixed layer in this complex, wake island environment. The model was compared to CTD data collected from sea gliders and tests for correlation were conducted. For mixed layer depths that did show correlation, match paired t …

New Dual Initiators For Polyisobutylene-Based Block And Star Polymers, Yaling Zhu

Dissertations

Polyisobutylene (PIB), available solely by living carbocationic polymerization (LCP), is a commercially important polymer with excellent thermal stability, good flexibility and extraordinary impermeability to gases. Due to these attractive properties, coupling PIB to other polymer blocks is expected to result in new and useful products. Two types of new dual initiators possessing initiating sites for both LCP and atom transfer radical polymerization (ATRP), have been designed for the preparation of AB linear and A2B miktoarm star copolymers, where A is PIB-based block copolymer that grows cationically and B is polyacrylate or other radically-derived polymer block, without intermediate modification.

Mono-cationic mono-radical …

Modern Approaches For Multifunctional Hydrolyzying Thiol-Ene Networks, Nicole Marie Mackey

Dissertations

Marine fouling has been an expensive and time-consuming process for navies and fishermen by the accumulation of marine algae and animals on artificial surfaces. Many coatings have been proposed to combat marine fouling in efforts to extend the lifetime of objects immersed in sea water. However, all coatings tested have either failed to resist fouling for a significant length of time or have released toxins into the environment. We have investigated an environmentally friendly approach to address the problem of marine fouling through the synthesis and preparation of a biocidal and a self-polishing coating. Both novel monomers were prepared containing …

Surface, Bulk, And Rheological Properties Of Polyhedral Oligomeric Silsesquioxane/High Density Polyethylene Nanocomposites, Robert Douglas Cook Jr.

Dissertations

In the formulation of high performance nanocomposites, control of miscibility and dispersion of filler material through a polymer matrix is of utmost importance. Due to their inorganic nature most nanofillers are insoluble in polymers, leading to costly/complicated surface modification as a primary means of increasing miscibility and interaction with organic matrices. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals offer an attractive alternative to conventional nanofillers. Due to their hybrid organic-inorganic nature, POSS has the potential to be tailored for miscibility in a wide range of organic matrices not by chemical surface modification but through modification of the molecular structure of the …

A Bisphenol-A-Based Resin System That Cures Via Triazole Ring Formation For Marine Composite Applications, Irene Elizabeth Gorman

Dissertations

Large composite panels, such as those utilized in marine applications, cannot be economically cured in an autoclave. For these structures the elevated temperatures necessary to achieve high crosslink density must come from the curing reaction itself. We are developing a resin system that cures via triazole ring formation (cycloaddition reaction of azides with terminal alkynes) instead of the traditional oxirane/amine reaction. The high exothermicity of the azido/alkyne reaction is expected to yield higher extents of reaction under ambient-cure conditions, making the resin system potentially suitable for "out-of-autoclave" curing processes. This work was conducted through a multi-tiered approach involving synthesis, kinetic …

Error Estimation Techniques To Refine Overlapping Aerial Image Mosaic Processes Via Detected Parameters, William Glenn Bond

Dissertations

In this paper, I propose to demonstrate a means of error estimation preprocessing in the assembly of overlapping aerial image mosaics. The mosaic program automatically assembles several hundred aerial images from a data set by aligning them, via image registration using a pattern search method, onto a GIS grid.

The method presented first locates the images from a data set that it predicts will not align well via the mosaic process, then it uses a correlation function, optimized by a modified Hooke and Jeeves algorithm, to provide a more optimal transformation function input to the mosaic program. Using this improved …

Approximation Of Elements Of Exponentials Of Differential Operators With Rational Quadrature, Daniel Elwood Lanterman

Master's Theses

We explore the possibility of improving the accuracy of approximations of elements of exponentials of differential operators, by using a rational function, instead of a polynomial function, as the interpolating function. Since a rational function behaves more like a decaying exponential function, it seems logical that the approximation should be more accurate. Through the use of high accuracy rational interpolants, we experiment with a numerical integration method to determine explicitly whether the error produced by a rational type approximation will indeed be less than that produced by a polynomial type approximation.

A Comparison Of Two Boundary Methods For Biharmonic Boundary Value Problems, Jaeyoun Oh

Master's Theses

The purpose of this thesis is to solve biharmonic boundary value problems using two different boundary methods and compare their performances. The two boundary methods used are the method of fundamental solutions (MFS) and the method of approximate fundamental solutions (MAFS). The Delta-shaped basis function with the Abel regularization technique is used in the construction of the approximate fundamental solutions in MAFS. The MFS produces more accurate results but needs known fundamental solutions for the differential operator. The MAFS can provide comparable results, and is applicable to more general differential operators. The numerical results using both methods are presented.

Rapid Approximation Of Bilinear Forms Involving Matrix Functions Through Asymptotic Analysis Of Gaussian Node Placement, Elisabeth Marie Palchak

Master's Theses

Technological advancements have allowed computing power to generate high resolution model s. As a result, greater stiffness has been introduced into systems of ordinary differential equations (ODEs) that arise from spatial discreti zation of partial differential equations (PDEs). The components of the solutions to these systems are coupled and changing at widely varying rates, which present problems for time-stepping methods. Krylov Subspace Spectral methods, developed by Dr. James Lambers, bridge the gap between explicit and implicit methods for stiff problems by computing each Fouier coefficient from an individualized approximation of the solution operator. KSS methods demonstrate a high order of …

Ph-Responsive Polymers For Biosurfaces: An Investigation Of Solution Properties And Surface Modifying Performance, Yuhong Wei

Master's Theses

Gantrez® copolymers are used widely in the personal care industry, but their mechanisms of interaction with dental surfaces are poorly understood. In this study, we determined a number of the solution and polymer properties that control deposition, adsorption and adhesion in Gantrez® polymer aqueous solutions to model dental surfaces. QCM studies specifically showed that polymer adsorption to model hydroxyapatite surfaces occurred only in solutions with polymer concentration above c*. Adsorption and adhesion was greater in solutions of higher pH, where greater charge density along the polymer backbone was expected. For films prepared via spin-coating onto mica surfaces, addition of surfactants …

Molecular Network Development Of A Thermosetting Epoxy-Amine Polymer, Christopher Michael Sahagun

Dissertations

i ABSTRACT MOLECULAR NETWORK DEVELOPMENT OF A THERMOSETTING EPOXY-AMINE POLYMER by Christopher Michael Sahagun May 2012 Epoxy-amine resins find wide application as the matrix material of high performance polymer composites due to their favorable mechanical properties, thermal properties and solvent stability. These properties are derived from the complicated, highly crosslinked molecular network that is characteristic of these thermoset polymers. The connectivity of the molecular network has a strong influence on the physical performance of the finished part. Non-homogeneity in the network structure can degrade these favorable properties through the introduction of low-energy pathways for solvent penetration or fracture propagation. This …