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Articles 3631 - 3660 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Discrete Wave Propagation In Quadratically Nonlinear Media, Robert Iwanow Jan 2005

Discrete Wave Propagation In Quadratically Nonlinear Media, Robert Iwanow

Electronic Theses and Dissertations

Discrete models are used in describing various microscopic phenomena in many branches of science, ranging from biology through chemistry to physics. Arrays of evanescently coupled, equally spaced, identical waveguides are prime examples of optical structures in which discrete dynamics can be easily observed and investigated. As a result of discretization, these structures exhibit unique diffraction properties with no analogy in continuous systems. Recently nonlinear discrete optics has attracted a growing interest, triggered by the observation of discrete solitons in AlGaAs waveguide arrays reported by Eisenberg et al. in 1998. So far, the following experiments involved systems with third order nonlinearities. …


Optimizing The Performance Of As-Manufactured Grazing Incidence X-Ray Telescopes Using Mosaic Detector Arrays, Martina Atanassova Jan 2005

Optimizing The Performance Of As-Manufactured Grazing Incidence X-Ray Telescopes Using Mosaic Detector Arrays, Martina Atanassova

Electronic Theses and Dissertations

The field of X-ray astronomy is only forty (43) years old, and grazing incidence X-ray telescopes have only been conceived and designed for a little over fifty (50) years. The Wolter Type I design is particularly well suited for stellar astronomical telescopes (very small field-of-view). The first orbiting X-ray observatory, HEAO-1 was launched in 1977, a mere twenty-eight (28) years ago. Since that time large nested Wolter Type I X-ray telescopes have been designed, build, and launched by the European Space Agency (ROSAT) and NASA (the Chandra Observatory). Several smaller grazing incidence telescopes have been launched for making solar observations …


The Effects Of Electrode Geometry On Current Pulse Caused By Electrical Discharge Over An Ultra-Fast Laser Filament, Matthew Bubelnik Jan 2005

The Effects Of Electrode Geometry On Current Pulse Caused By Electrical Discharge Over An Ultra-Fast Laser Filament, Matthew Bubelnik

Electronic Theses and Dissertations

The time-resolved electrical conductivity of a short-pulse generated plasma filament in air was studied. Close-coupled metal electrodes were used to discharge the stored energy of a high-voltage capacitor and the resulting microsecond-scale electrical discharge was measured using fast current sensors. Significant differences in the time dependence of the current were seen with the two electrode geometries used. Using sharp-tipped electrodes additional peaks in the time-resolved conductivity were seen, relative to the single peak seen with spherical electrodes. We attribute these additional features to secondary electron collisional ionization brought about by field enhancement at the tips. Additional discrepancies in the currents …


Design And Assessment Of Compact Optical Systems Towards Special Effects Imaging, Vesselin Chaoulov Jan 2005

Design And Assessment Of Compact Optical Systems Towards Special Effects Imaging, Vesselin Chaoulov

Electronic Theses and Dissertations

A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach …


Liquid Crystal Materials And Tunable Devices For Optical Communications, Fang Du Jan 2005

Liquid Crystal Materials And Tunable Devices For Optical Communications, Fang Du

Electronic Theses and Dissertations

In this dissertation, liquid crystal materials and devices are investigated in meeting the challenges for photonics and communications applications. The first part deals with polymer-stabilized liquid crystal (PSLC) materials and devices. Three polymer-stabilized liquid crystal systems are developed for optical communications. The second part reports the experimental investigation of a novel liquid-crystal-infiltrated photonic crystal fiber (PCF) and explores its applications in fiber-optic communications. The curing temperature is found to have significant effects on the PSLC performance. The electro-optic properties of nematic polymer network liquid crystal (PNLC) at different curing temperatures are investigated experimentally. At high curing temperature, a high contrast, …


Data Structures And Algorithms For Efficient Solution Of Simultaneous Linear Equations From 3-D Ice Sheet Models, Rodney A. Jacobs Jan 2005

Data Structures And Algorithms For Efficient Solution Of Simultaneous Linear Equations From 3-D Ice Sheet Models, Rodney A. Jacobs

Electronic Theses and Dissertations

Two current software packages for solving large systems of sparse simultaneous l~neare equations are evaluated in terms of their applicability to solving systems of equations generated by the University of Maine Ice Sheet Model. SuperLU, the first package, has been developed by researchers at the University of California at Berkeley and the Lawrence Berkeley National Laboratory. UMFPACK, the second package, has been developed by T. A. Davis of the University of Florida who has ties with the U. C. Berkeley researchers as well as European researchers. Both packages are direct solvers that use LU factorization with forward and backward substitution. …


Kinetics And Mechanism Of The Catalysis Of The Decomposition Of Hydrogen Peroxide By Schiff Base Complexes Of Copper(Ii)., Timothy Kum Beng Dec 2004

Kinetics And Mechanism Of The Catalysis Of The Decomposition Of Hydrogen Peroxide By Schiff Base Complexes Of Copper(Ii)., Timothy Kum Beng

Electronic Theses and Dissertations

Spectroscopic studies have been used to describe the mechanism of the decomposition of hydrogen peroxide by solutions of a dimeric Cu(II) complex of a dissymetric Schiff base, [CuSALAD]2.H2O, and imidazole or methyl substituted imidazoles, B, which form monomeric CuSALAD.B2 complexes, in aqueous ethanol solvent. Freezing point depression and vapor pressure lowering studies were carried out to confirm the dimeric nature of the [CuSALAD]2.H2O complex that had been previously reported. The stoichiometry of the [CuSALAD]2.H2O-imidazole equilibrium was extensively studied pointing to a 1:4 stoichiometry. The CuSALAD.B2 adducts …


Maldi-Tof Ms Data Processing Using Wavelets, Splines And Clustering Techniques., Shuo Chen Dec 2004

Maldi-Tof Ms Data Processing Using Wavelets, Splines And Clustering Techniques., Shuo Chen

Electronic Theses and Dissertations

Mass Spectrometry, especially matrix assisted laser desorption/ionization (MALDI) time of flight (TOF), is emerging as a leading technique in the proteomics revolution. It can be used to find disease-related protein patterns in mixtures of proteins derived from easily obtained samples. In this paper, a novel algorithm for MALDI-TOF MS data processing is developed. The software design includes the application of splines for data smoothing and baseline correction, wavelets for adaptive denoising, multivariable statistics techniques such as clustering analysis, and signal processing techniques to evaluate the complicated biological signals. A MatLab implementation shows the processing steps consecutively including step-interval unification, adaptive …


Requirement Elicitation Of Large Web Projects., David E. Frazier Dec 2004

Requirement Elicitation Of Large Web Projects., David E. Frazier

Electronic Theses and Dissertations

One of the most important aspects of developing a large Web-based project is getting the correct requirements from the client. Time and money can be lost if the requirements are incomplete or inaccurate. Traditional Web design sources tend to gloss over this important activity.

Software engineering is a mature field that can help in the quest for more complete and accurate requirement gathering. This paper explores the ways that traditional software engineering techniques can be applied to Web projects. A methodology is presented based on both existing and new techniques. Several experiments are conducted to determine the usefulness of each …


Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall Dec 2004

Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall

Electronic Theses and Dissertations

Events in the world do not occur in neat chronological order, but may take place, for example, during or overlapping each other, or as simultaneous events. Efficient summaries of real-world events are important in many disciplines and require events to be modeled in a linear fashion. This thesis focuses on modeling events as intervals and using relations between the events to derive linear orders from more complex partially ordered sets. A method is developed for mapping Allen's thirteen temporal relations to only two relations, before and equals, which allow a linear ordering of all events present in the set. This …


Risk Perceptions Of Adults In The Town Of Unicoi, Tennessee, Regarding The Possible Building Of A Uranium Enrichment Plant., Shannon Kathleen Sellards Dec 2004

Risk Perceptions Of Adults In The Town Of Unicoi, Tennessee, Regarding The Possible Building Of A Uranium Enrichment Plant., Shannon Kathleen Sellards

Electronic Theses and Dissertations

A prolonged siting controversy for a uranium enrichment facility has occurred in the Town of Unicoi, Tennessee. One hundred-seventy residents of Unicoi were interviewed using a questionnaire regarding the building of a proposed uranium enrichment facility for Unicoi. The questionnaire sought to determine relationships between residents’ risk perceptions and 18 variables. When the Fisher’s exact procedure was applied at α< 0.05, the results indicated several associations. Odds ratio measured the strength of association. Results are reported as crude measures of association. Risk perceptions were influenced by the choice of possible locations for the facility [p=0.0003; OR=32.6]. Residents' risk perceptions were associated with a history of working with nuclear materials [p=0.0476; OR=3.2]. Finally, risk perceptions were associated with residents' beliefs that the nuclear facility would affect their health [p=0.0001; OR=18.8]. These results are discussed in light of risk perception and communication theories.


Temporal Variability Of Satellite-Derived Chlorophyll And Sea Suface Temperature In The California Current, Kasey Legaard Dec 2004

Temporal Variability Of Satellite-Derived Chlorophyll And Sea Suface Temperature In The California Current, Kasey Legaard

Electronic Theses and Dissertations

Physical forcing and biological response within the California Current coastal upwelling system are highly variable over a wide range of scales. Satellite remote sensing offers the only feasible means of quantifying this variability over the full extent of this current system. Here we quantify and compare patterns of physical and biological variability acting over seasonal, interannual and dominant intraseasonal time scales throughout the California Current System using more than five years (1997-2003) of daily SeaWiFS chlorophyll and NOAA/NASA AVHRR Oceans Pathfinder SST imagery. Mean seasonal cycles were modeled as the sum of annual and semiannual harmonics. Interannual variability was estimated …


Estimating The Economic Recreational Value Of Paracas National Reserve In Ica Peru: A Fair Fee Implementation Approach, Jaqueline Garcia-Yi Dec 2004

Estimating The Economic Recreational Value Of Paracas National Reserve In Ica Peru: A Fair Fee Implementation Approach, Jaqueline Garcia-Yi

Electronic Theses and Dissertations

Paracas National Reserve (PNR) is one of the fifty-seven protected areas that belong to the National System of Protected Areas (SINANPE) of Peru. Located in Ica Department, on the Pacific coast of Peru, it is the only coastal-marine ecosystem currently protected by the Peruvian government. PNR has been internationally recognized, principally as a wintering area for bird migrations. It has been designated as a Regional Shorebird Reserve by the Western Hemisphere Shorebird Reserve Network (1991), a Ramsar site by the Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat (1992), and a Particular Sensitive Sea Area by the …


Ir Studies Of The Interaction Of Surfactants And Polyelectrolytes Adsorbed On Tio2 Particles, Haiyan Li Dec 2004

Ir Studies Of The Interaction Of Surfactants And Polyelectrolytes Adsorbed On Tio2 Particles, Haiyan Li

Electronic Theses and Dissertations

Polymers/surfactants are used to control and modify the interfacial properties of particulate suspensions. The resulting properties are dependent on the amount of adsorbed surfactants/polymers on the surface as well as the nature of the aggregated structures. Often these interactions are complex and not well understood. In this thesis we have used Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) to identify surfactant, mixed surfactant, polyelectrolyte and mixed polyelectrolyte surfactant structures formed on charged Ti02 particles. In addition, the change occurring to the structure of an adsorbed polymer layer on Ti02 to flowing suspension of silica particles was studied. A …


Context-Specific Preference Learning Of One Dimensional Quantitative Geospatial Attributes Using A Neuro-Fuzzy Approach, Georgios Mountrakis Dec 2004

Context-Specific Preference Learning Of One Dimensional Quantitative Geospatial Attributes Using A Neuro-Fuzzy Approach, Georgios Mountrakis

Electronic Theses and Dissertations

Change detection is a topic of great importance for modern geospatial information systems. Digital aerial imagery provides an excellent medium to capture geospatial information. Rapidly evolving environments, and the availability of increasing amounts of diverse, multiresolutional imagery bring forward the need for frequent updates of these datasets. Analysis and query of spatial data using potentially outdated data may yield results that are sometimes invalid. Due to measurement errors (systematic, random) and incomplete knowledge of information (uncertainty) it is ambiguous if a change in a spatial dataset has really occurred. Therefore we need to develop reliable, fast, and automated procedures that …


Using Linear Features For Aerial Image Sequence Mosaiking, Caixia Wang Dec 2004

Using Linear Features For Aerial Image Sequence Mosaiking, Caixia Wang

Electronic Theses and Dissertations

With recent advances in sensor technology and digital image processing techniques, automatic image mosaicking has received increased attention in a variety of geospatial applications, ranging from panorama generation and video surveillance to image based rendering. The geometric transformation used to link images in a mosaic is the subject of image orientation, a fundamental photogrammetric task that represents a major research area in digital image analysis. It involves the determination of the parameters that express the location and pose of a camera at the time it captured an image. In aerial applications the typical parameters comprise two translations (along the x …


Wetland And Nest Scale Habitat Use By The Four-Toed Salamander (Hemidactylium Scutatum) In Maine, And A Comparison Of Survey Methods, Rebecca J. Chalmers Dec 2004

Wetland And Nest Scale Habitat Use By The Four-Toed Salamander (Hemidactylium Scutatum) In Maine, And A Comparison Of Survey Methods, Rebecca J. Chalmers

Electronic Theses and Dissertations

Conserving amphibian populations requires knowledge of a species and its habitat relationships. The four-toed salamander (Hemidactylium scutatum) is listed as Special Concern in Maine and 11 additional states and provinces, Threatened in Illinois, and Endangered in Indiana (Appendix A). Little is known of H. scutatum ecology despite the species' extensive range. Infrequent sightings of H. scutatum throughout its range may indicate either low numbers or that the species' behavior make detection difficult. Records for H. scutatum in Maine existed from only 32 sites before my study, and the total number of occurrences of this species in Maine is …


Using The Em Algorithm To Estimate The Difference In Dependent Proportions In A 2 X 2 Table With Missing Data., Alain Duclaux Talla Souop Aug 2004

Using The Em Algorithm To Estimate The Difference In Dependent Proportions In A 2 X 2 Table With Missing Data., Alain Duclaux Talla Souop

Electronic Theses and Dissertations

In this thesis, I am interested in estimating the difference between dependent proportions from a 2 × 2 contingency table when there are missing data. The Expectation-Maximization (EM) algorithm is used to obtain an estimate for the difference between correlated proportions. To obtain the standard error of this difference I employ a resampling technique known as bootstrapping. The performance of the bootstrap standard error is evaluated for different sample sizes and different fractions of missing information. Finally, a 100(1-α)% bootstrap confidence interval is proposed and its coverage is evaluated through simulation.


A Data Model For Exploration Of Temporal Virtual Reality Geographic Information Systems, Jorge Alberto Prado De Campos Aug 2004

A Data Model For Exploration Of Temporal Virtual Reality Geographic Information Systems, Jorge Alberto Prado De Campos

Electronic Theses and Dissertations

Geographic information systems deal with the exploration, analysis, and presentation of geo-referenced data. Virtual reality is a type of human-computer interface that comes close to the way people perceive information in the real world. Thus, virtual reality environments become the natural paradigm for extending and enhancing the presentational and exploratory capability of GIs applications in both the spatial and temporal domains. The main motivation of this thesis is the lack of a framework that properly supports the exploration of geographic information in a multi-dimensional and multi-sensorial environment (i.e., temporal virtual reality geographic information systems). This thesis introduces a model for …


Biology And Ecology Of Larval Lobsters (Homarus Americanus): Implications For Population Connectivity And Larval Transport, Eric R. Annis Aug 2004

Biology And Ecology Of Larval Lobsters (Homarus Americanus): Implications For Population Connectivity And Larval Transport, Eric R. Annis

Electronic Theses and Dissertations

The connectivity of marine populations and the degree to which they are considered open or closed has important implications for the ecology, management, and resilience of commercially harvested species. Larval exchange is a primary determinant of the level of connectivity between populations, and this thesis examines the intrinsic and extrinsic factors influencing larval transport and the distribution of larvae of the American lobster (Homarus americanus). The potential for larval transport is directly proportional to the planktonic larval duration. Our field data suggest development times in situ were up to three times faster than previous laboratory development times, indicating that potential …


Differentials Of Graphs., Jason Robert Lewis May 2004

Differentials Of Graphs., Jason Robert Lewis

Electronic Theses and Dissertations

Let G=(V,E) be an arbitrary graph, and consider the following game. You are allowed to buy as many tokens from a bank as you like, at a cost of $1 each. For example, suppose you buy k tokens. You then place the tokens on some subset of k vertices of V. For each vertex of G which has no token on it, but is adjacent to a vertex with a token on it, you receive $1 from the bank. Your objective is to maximize your profit, that is, the total value received from the …


A Vulnerability Assessment Of The East Tennessee State University Administrative Computer Network., James Patrick Ashe May 2004

A Vulnerability Assessment Of The East Tennessee State University Administrative Computer Network., James Patrick Ashe

Electronic Theses and Dissertations

A three phase audit of East Tennessee State University's administrative computer network was conducted during Fall 2001, Spring 2002, and January 2004. Nmap and Nessus were used to collect the vulnerability data. Analysis discovered an average of 3.065 critical vulnerabilities per host with a low of 2.377 in Spring 2001 to a high of 3.694 in Fall 2001. The number of unpatched Windows operating system vulnerabilities, which accounted for over 75% of these critical vulnerabilities, strongly argues for the need of an automated patch deployment system for the approximately 3,000 Windows-based systems at ETSU.


Determination Of Lactose By Reversed-Phase High Performance Liquid Chromatography., Danessa Leann Sexton May 2004

Determination Of Lactose By Reversed-Phase High Performance Liquid Chromatography., Danessa Leann Sexton

Electronic Theses and Dissertations

Lactose is the common disaccharide found in dairy products. It can, however, be a source of discomfort for those whom are lactose intolerant. Therefore, it is necessary to accurately, reliably, and efficiently determine the lactose content of foods. The goal of this research was to develop a reversed-phase HPLC method with UV detection for the determination of lactose. Aminobenzoic acid was used to prepare a derivative, making detection possible in the 300-360 nm region. The stationary phase is a C8 column, with 85% methanol 15% water mixture at pH 5 as the mobile phase. A linear response of peak area …


Locating And Total Dominating Sets In Trees., Jamie Marie Howard May 2004

Locating And Total Dominating Sets In Trees., Jamie Marie Howard

Electronic Theses and Dissertations

A set S of vertices in a graph G=(V,E) is a total dominating set of G if every vertex of V is adjacent to some vertex in S. In this thesis, we consider total dominating sets of minimum cardinality which have the additional property that distinct vertices of V are totally dominated by distinct subsets of the total dominating set.


Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks May 2004

Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks

Electronic Theses and Dissertations

Wayfinders typically travel in dynamic environments where barriers and requirements change over time. In many cases, uncertainty exists about the future state of this changing environment. Current geographic information systems lack tools to assist wayfinders in understanding the travel possibilities and path selection options in these dynamic and uncertain settings. The goal of this research is a better understanding of the impact of dynamic and uncertain environments on wayfinding travel possibilities. An integrated spatio-temporal framework, populated with barriers and requirements, models wayfinding scenarios by generating four travel possibility partitions based on the wayfinder's maximum travel speed. Using these partitions, wayfinders …


Measures Of Concordance Of Polynomial Type, Heather Edwards Jan 2004

Measures Of Concordance Of Polynomial Type, Heather Edwards

Electronic Theses and Dissertations

A measure of concordance, $\kappa$, is of polynomial type if and only if $\kappa (tA+(1-t)B)$ is a polynomial in $t$ where $A$ and $B$ are 2-copulas. The degree of such a type of measure of concordance is simply the highest degree of the polynomial associated with $\kappa$. In previous work [2], [3], properties of measures of concordance preserving convex sums (equivalently measures of concordance of polynomial type degree one) were established; however, a characterization was not made. Here a characterization is made using approximations involving doubly stochastic matrices. Other representations are provided from this characterization leading naturally to two interpretations …


Study Of The Excited-State Absorption Properties Of Polymethine Molecules, Richard Stanley Lepkowicz Jan 2004

Study Of The Excited-State Absorption Properties Of Polymethine Molecules, Richard Stanley Lepkowicz

Electronic Theses and Dissertations

This dissertation investigates excited-state nonlinearities in a series of polymethine dyes for the application of nanosecond optical limiting. Optical limiters are devices that for low intensity light exhibit a high linear transmittance, but for high intensity light strongly attenuate the incident radiation. These devices would serve to protect optical sensors from intense laser radiation by clamping the maximum energy allowed through an optical system below the damage threshold of the sensor. The search is ongoing for optical materials that are both broadband and have high damage thresholds to be effective materials for limiting applications. Polymethine dyes are promising compounds due …


Camera System Support For Highway Transportation Using Mobile Devices, Le Minh Jan 2004

Camera System Support For Highway Transportation Using Mobile Devices, Le Minh

Electronic Theses and Dissertations

With the very fast growing technology in wireless, advancement in hardware and the dramatically falling cost of mobile computing devices such as PDA, handheld device, People nowadays can have a personal device that fits in their hand but has computing power as a desktop did few years ago. The same device now is able to communicate over a wireless network and view office document at the same time. The combination of size, power and flexibility makes the personal devices increasingly appear in many aspects of life. In this proposal, we focus on a simple yet useful application of mobile devices …


Macmahon's Master Theorem And Infinite Dimensional Matrix Inversion, Vivian Lola Wong Jan 2004

Macmahon's Master Theorem And Infinite Dimensional Matrix Inversion, Vivian Lola Wong

Electronic Theses and Dissertations

MacMahon's Master Theorem is an important result in the theory of algebraic combinatorics. It gives a precise connection between coefficients of certain power series defined by linear relations. We give a complete proof of MacMahon's Master Theorem based on MacMahon's original 1960 proof. We also study a specific infinite dimensional matrix inverse due to C. Krattenthaler.


Asymptotic Formulas For Large Arguments Of Hypergeometric-Type Functio, Adam Heck Jan 2004

Asymptotic Formulas For Large Arguments Of Hypergeometric-Type Functio, Adam Heck

Electronic Theses and Dissertations

Hypergeometric type functions have a long list of applications in the field of sciences. A brief history is given of Hypergeometric functions including some of their applications. A development of a new method for finding asymptotic formulas for large arguments is given. This new method is applied to Bessel functions. Results are compared with previously known methods.