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Initial-Value Technique For Singularly Perturbed Two Point Boundary Value Problems Via Cubic Spline, Luis G. Negron 2010 University of Central Florida

Initial-Value Technique For Singularly Perturbed Two Point Boundary Value Problems Via Cubic Spline, Luis G. Negron

Electronic Theses and Dissertations

A recent method for solving singular perturbation problems is examined. It is designed for the applied mathematician or engineer who needs a convenient, useful tool that requires little preparation and can be readily implemented using little more than an industry-standard software package for spreadsheets. In this paper, we shall examine singularly perturbed two point boundary value problems with the boundary layer at one end point. An initial-value technique is used for its solution by replacing the problem with an asymptotically equivalent first order problem, which is, in turn, solved as an initial value problem by using cubic splines. Numerical examples ...


Experimental And Theoretical Study Of The Optical Properties Of Semiconductor Quantum Dots, Gero Nootz 2010 University of Central Florida

Experimental And Theoretical Study Of The Optical Properties Of Semiconductor Quantum Dots, Gero Nootz

Electronic Theses and Dissertations

The aim of this dissertation is to gain a better understanding of the unique electronic structure of lead salt quantum dots (QDs) and its influences on the nonlinear optical (NLO) properties as well as the time dynamics of the photogenerated charge carriers. A variety of optical techniques such as Z-scan, two-photon excited fluorescence and time-resolved pump probe spectroscopy are used to measure these properties. The one-photon as well as the degenerate and nondegenerate two-photon absorption (2PA) spectra are measured and the electronic wave functions from a four-band envelope function formalism are used to model the results. We observe local maxima ...


Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak 2010 University of Central Florida

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak

Electronic Theses and Dissertations

Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA ...


Physicochemical And Thermochemical Properties Of Sulfonated Poly(Etheretherketone) Electrolyte Membranes, Stephen Rhoden 2010 University of Central Florida

Physicochemical And Thermochemical Properties Of Sulfonated Poly(Etheretherketone) Electrolyte Membranes, Stephen Rhoden

Electronic Theses and Dissertations

Fuel cells have long been seen as an alternative to combustion powered and diesel powered engines and turbines. Production of energy via a fuel cell conversion method can generate up to 60% efficiency in comparison to 30% using a combustion powered engine, with low co-production of harmful side-products. The polymer electrolyte membrane (PEM) adapted for the fuel cell application is one of the main components that determines the overall efficiency. This research project was focused towards novel PEMs, such as sulfonated poly(etheretherketone) or SPEEK, which are cost-efficient and robust with high proton conductivities under hydrated conditions. The degree of ...


Laboratory Studies To Field Evaluation : Remediation Of Polychlorinated Biphenyl Contaminated Painted Surfaces Through The Use Of Activated Metal Treatment Systems, Erin Kristen Saitta 2010 University of Central Florida

Laboratory Studies To Field Evaluation : Remediation Of Polychlorinated Biphenyl Contaminated Painted Surfaces Through The Use Of Activated Metal Treatment Systems, Erin Kristen Saitta

Electronic Theses and Dissertations

Polychlorinated Biphenyls (PCBs) are a group of 209 congeners that are regulated under the Toxic Substance Control Act. They enter the environment as a result of industrial processes and can travel long distances. PCBs are environmentally persistent and bioaccumulate in animal populations. Painted surfaces are a common point source for PCBs and there are few options for remediating structures painted with PCB-contaminated paint. Removal of the paint can often spread contamination and disposing or burning of large structures is expensive. Experiments employing reductive dehalogenation through the use of a bimetal have shown that PCBs can be degraded in mild laboratory ...


The Fabrication Of Polymer-Derived Sicn/Sibcn Ceramic Nanostructures And Investigation Of Their Structure-Property Relationship, Sourangsu Sarkar 2010 University of Central Florida

The Fabrication Of Polymer-Derived Sicn/Sibcn Ceramic Nanostructures And Investigation Of Their Structure-Property Relationship, Sourangsu Sarkar

Electronic Theses and Dissertations

Polymer-derived Ceramics (PDCs) represent a unique class of high-temperature stable materials synthesized directly by the thermal decomposition of polymers. This research first focuses on the fabrication of high temperature stable siliconcarbonitride (SiCN) fibers by electrospinning for ceramic matrix composite (CMC) applications. Ceraset™ VL20, a commercially available liquid cyclosilazane, was functionalized with aluminum sec-butoxide in order to be electrospinnable. The surface morphology of the electrospun fibers was investigated using the fibers produced from solvents. The electrospun fibers produced from the chloroform/N,N-dimethylformamide solutions had hierarchical structures that led to superhydrophobic surfaces. A “dry skin” model was proposed to explain the ...


An Assessment Of Sea Turtle Nesting Behavior In Relation To Hurricane- And Restoration-Induced Beach Morphodynamics, Tonya Michele Long 2010 University of Central Florida

An Assessment Of Sea Turtle Nesting Behavior In Relation To Hurricane- And Restoration-Induced Beach Morphodynamics, Tonya Michele Long

Electronic Theses and Dissertations

Coastal habitats are highly dynamic and vulnerable to landscape-level disturbances such as storms and restoration projects. Along the east coast of Florida these areas are particularly valuable as they provide significant nesting habitat for two sea turtle species, the threatened loggerhead (Caretta caretta) and the endangered green turtle (Chelonia mydas). This coast was heavily impacted by three major hurricanes in 2004 and in some areas by large restoration projects in 2005. Recent remote sensing methods allow for broad evaluation of the shoreline and thus the ability to assess sea turtle nesting habitat at a landscape scale. I collected nesting data ...


Species Composition And Spatiotemporal Pattern Of The Seed Bank And Vegetation In Native And Degraded Florida Rosemary Scrub, Jennifer J. Navarra 2010 University of Central Florida

Species Composition And Spatiotemporal Pattern Of The Seed Bank And Vegetation In Native And Degraded Florida Rosemary Scrub, Jennifer J. Navarra

Electronic Theses and Dissertations

The soil seed bank plays a dynamic role in the regeneration of plant communities after natural and anthropogenic disturbance. In this thesis, I addressed how disturbances influence the vegetation and seed bank of Florida rosemary scrub. In Chapter One I evaluated changes in species composition and spatiotemporal pattern of the vegetation and seed bank along a gradient of disturbance. During the summers and winters of 2007-2009 percent ground cover and seed bank species composition were assessed among replicates of three vegetation types subjected to minimal, moderate, and extreme anthropogenic disturbance (native rosemary scrub, degraded scrub, and agriculturally improved pasture, respectively ...


Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices, Paul Stokes 2010 University of Central Florida

Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices, Paul Stokes

Electronic Theses and Dissertations

Developing techniques for the parallel fabrication of Complementary Metal Oxide Semiconductor (CMOS) compatible single walled carbon nanotube (SWNT) electronic devices is of great importance for nanoelectronic applications. In this thesis, solution processed SWNTs in combination with AC dielectrophoresis (DEP) were utilized to fabricate CMOS compatible SWNT field effect transistors (FETs) and single electron transistors (SETs) with high yield and their detailed electronic transport properties were studied. Solution processing of SWNTs is attractive not only for the high throughput and parallel manufacturing of SWNT devices but also due to the ease of processing at room temperature, and compatibility with various substrates ...


Development Of Reductive Metal Systems For The Degradation Of Energetic Compounds (Tatp, Tnt, And Rdx), Rebecca L. Albo 2010 University of Central Florida

Development Of Reductive Metal Systems For The Degradation Of Energetic Compounds (Tatp, Tnt, And Rdx), Rebecca L. Albo

Electronic Theses and Dissertations

Triacetone triperoxide (TATP), a cyclic peroxide explosive, is frequently used by terrorists and amateur chemists due to the ease of synthesis and the availability of reagents. TATP is extremely sensitive to shock, heat, and friction thus a safe and rapid method for treating TATP is needed. The major objective of this dissertation was to develop in situ methodologies that could safely degrade TATP in various field situations. Initial studies focused on using zero-valent metals and mechanically alloyed metals to decompose TATP samples in both aqueous and organic solutions. The metal systems tested included zero-valent iron, magnesium, and magnesium bimetal, Mg ...


Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu 2010 University of Central Florida

Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu

Electronic Theses and Dissertations

The general goal of this dissertation is to provide a comprehensive description of the limitations of established theories on bound electronic nonlinearities in direct-gap semiconductors by performing various experiments on wide and narrow bandgap semiconductors along with developing theoretical models. Nondegenerate two-photon absorption (2PA) is studied in several semiconductors showing orders of magnitude enhancement over the degenerate counterpart. In addition, three-photon absorption (3PA) is studied in ZnSe and other semiconductors and a new theory using a Kane 4-band model is developed which fits new data well. Finally, the narrow gap semiconductor InSb is studied with regard to multiphoton absorption, free-carrier ...


New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir 2010 University of Central Florida

New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir

Electronic Theses and Dissertations

The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold ...


Search For Gas Giants Around Late-M Dwarfs, Rohit Deshpande 2010 University of Central Florida

Search For Gas Giants Around Late-M Dwarfs, Rohit Deshpande

Electronic Theses and Dissertations

We carried out a near-infrared radial velocity search for Jupiter-mass planets around 36 late M dwarfs. This survey was the first of its kind undertaken to monitor radial velocity variability of these faint dwarfs. For this unique survey we employed the 10-m Keck II on Mauna Kea in Hawaii. With a resolution of 20,000 on the near-infrared spectrograph, NIRSPEC, we monitored these stars over four epochs in 2007. In addition to the measurement of relative radial velocity we established physical properties of these stars. The physical properties of M dwarfs we determined included the identification of neutral atomic lines ...


Statistical Analysis Of Visible Absorption Spectra And Mass Spectra Obtained From Dyed Textile Fibers, Katie Margaret White 2010 University of Central Florida

Statistical Analysis Of Visible Absorption Spectra And Mass Spectra Obtained From Dyed Textile Fibers, Katie Margaret White

Electronic Theses and Dissertations

The National Academy of Sciences recently published a report which calls for improvements to the field of forensic science. Their report criticized many forensic disciplines for failure to establish rigorously-tested methods of comparison, and encouraged more research in these areas to establish limitations and assess error rates. This study applies chemometric and statistical methods to current and developing analytical techniques in fiber analysis. In addition to analysis of commercially available dyed textile fibers, two pairs of dyes are selected based for custom fabric dyeing on the similarities of their absorbance spectra and dye molecular structures. Visible absorption spectra for all ...


An Improved Synthesis Of A Ring-C Precursor To Cobyric Acid, Hui Wang, Peter A. Jacobi 2010 Dartmouth College

An Improved Synthesis Of A Ring-C Precursor To Cobyric Acid, Hui Wang, Peter A. Jacobi

Open Dartmouth: Faculty Open Access Scholarship

Alkyne acid 10 was prepared in enantioselective fashion from allylic ester derivative (R)-18 via an E-selective Ireland-Claisen rearrangement followed by Si-assisted elimination of HBr. The present route offers significant advantages in terms of both scalability and overall yield compared to that previously described. Alkyne acid 10 is an attractive ring-C precursor for an ongoing synthesis of cobyric acid.


Plant Isotopes As Indicators Of N Cycling Processes In Agricultural Fields, Eric Thuss 2010 Wilfrid Laurier University

Plant Isotopes As Indicators Of N Cycling Processes In Agricultural Fields, Eric Thuss

Theses and Dissertations (Comprehensive)

When nitrogen (N) availability exceeds biological demand, excess N, especially nitrate (NO3), may subsequently pollute ground and surface water. Agricultural practices in Southern Ontario typically supplement soils with organic and inorganic nutrients to aid in crop development, and employ various management techniques to limit nutrient loss. Excess N has several potential fates, which are controlled by the net effects of numerous N cycling reactions in the soil that are often difficult to measure directly. N cycling in soils is controlled in large part by soil moisture, as it affects microbial activity and soil redox conditions. Stable isotope geochemistry is ...


Rethinking Biodiversity Conservation Effectiveness And Evaluation In The National Protected Areas Systems Of Tropical Islands: The Case Of Jamaica And The Dominican Republic, Suzanne Mae Camille Davis 2010 Wilfrid Laurier University

Rethinking Biodiversity Conservation Effectiveness And Evaluation In The National Protected Areas Systems Of Tropical Islands: The Case Of Jamaica And The Dominican Republic, Suzanne Mae Camille Davis

Theses and Dissertations (Comprehensive)

Island conservation theory and practice with regard to conservation of tropical terrestrial biodiversity in protected areas systems has yet to be adequately addressed in conservation literature. This knowledge gap is identified as a key contributor to the adoption of scientific principles for in situ biodiversity conservation, and “universal” conservation and protected area management paradigms that are unsuitable for island contexts and geographical scale. The underlying assumption is that “universal” concepts of biodiversity conservation, protected areas management, and evaluation of their effectiveness are transferable to the ecological and socio-economic contexts of tropical islands. The expected outcome of this knowledge transfer is ...


Ancient Dna Analyses Exclude Humans As The Driving Force Behind Late Pleistocene Musk Ox (Ovibos Moschatus) Population Dynamics, Paula F. Campos, Eske Willerslev, Andrei Sher, Ludovic Orlando, Erik Axelsson, Alexei Tikhonov, Kim Aaris-Sorensen, Alex D. Greenwood, Ralf-Dietrich Kahlke, Pavel Kosintsev 2010 Old Dominion University

Ancient Dna Analyses Exclude Humans As The Driving Force Behind Late Pleistocene Musk Ox (Ovibos Moschatus) Population Dynamics, Paula F. Campos, Eske Willerslev, Andrei Sher, Ludovic Orlando, Erik Axelsson, Alexei Tikhonov, Kim Aaris-Sorensen, Alex D. Greenwood, Ralf-Dietrich Kahlke, Pavel Kosintsev

Biological Sciences Faculty Publications

The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, or a combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived to the present. The musk ox has an intermediate story: relatively abundant during the Pleistocene, it is now restricted to Greenland and the Arctic Archipelago. In this study, we use ancient DNA sequences, temporally unbiased summary statistics, and Bayesian analytical techniques to infer musk ox population dynamics throughout the late Pleistocene and Holocene. Our results reveal ...


Stratovolcano Growth By Co-Eruptive Intrusion: The 2008 Eruption Of Tungurahua Ecuador, J. Biggs, P. Mothes, M. Ruiz, F. Amelung, Timothy H. Dixon, S. Baker, S-H. Hong 2010 University of Oxford

Stratovolcano Growth By Co-Eruptive Intrusion: The 2008 Eruption Of Tungurahua Ecuador, J. Biggs, P. Mothes, M. Ruiz, F. Amelung, Timothy H. Dixon, S. Baker, S-H. Hong

School of Geosciences Faculty and Staff Publications

Volcanic edifices are constructed by a combination of erupted material and internal growth. We use the L-band satellite ALOS to produce InSAR measurements at Tungurahua Volcano, Ecuador. We find a maximum of 17.5 cm of uplift on the upper western flank between December 2007 and March 2008, coincident with an eruption in February 2008. The deformation can be modeled using an ellipsoidal or sill-like source within the edifice. The models require an elongated aspect ratio with a length of 4–6 km. The intruded volume of 1.2 × 106 m3 is roughly equivalent to the bulk erupted ...


Planning The Future Of Geocybereducation, Jeffrey G. Ryan, Susan Eriksson 2010 University of South Florida

Planning The Future Of Geocybereducation, Jeffrey G. Ryan, Susan Eriksson

Geology Faculty Publications

No abstract provided.


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