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Articles 3391 - 3420 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Remediation Of Heavy Metal Contamination In Sediments: Application Of In Situ Treatment Utilizing Emulsified Liquid Membrane An, Deborah Maxwell Jan 2007

Remediation Of Heavy Metal Contamination In Sediments: Application Of In Situ Treatment Utilizing Emulsified Liquid Membrane An, Deborah Maxwell

Electronic Theses and Dissertations

Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated …

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A Mathematical Study Of Two Retroviruses, Hiv And Htlv-I, Dana Ali Baxley Jan 2007

A Mathematical Study Of Two Retroviruses, Hiv And Htlv-I, Dana Ali Baxley

Electronic Theses and Dissertations

In this thesis, we examine epidemiological models of two different retroviruses, which infect the human body. The two viruses under study are HIV or the human immunodefiency virus and HTLV-I, which is the human T lymphotropic virus type I. A retrovirus is a virus, which injects its RNA into the host, rather than it's DNA. We will study each of the different mathematical models for each of the viruses separately. Then we use MATLAB-SIMULINK to analyze the models by studying the reproductive numbers in each case and the disease progression by examining the graphs. In Chapter 1, we mention basic …

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Two-Photon 3d Optical Data Storage Via Fluorescence Modulation Of Fluorene Dyes By Photochromic Diarylethenes, Claudia Corredor Jan 2007

Two-Photon 3d Optical Data Storage Via Fluorescence Modulation Of Fluorene Dyes By Photochromic Diarylethenes, Claudia Corredor

Electronic Theses and Dissertations

Three-dimensional (3D) optical data storage based on two-photon processes provides highly confined excitation in a recording medium and a mechanism for writing and reading data with less cross talk between multiple memory layers, due to the quadratic dependence of two photon absorption (2PA) on the incident light intensity. The capacity for highly confined excitation and intrinsic 3D resolution affords immense information storage capacity (up to 1012 bits/cm3). Recently, the use of photochromic materials for 3D memory has received intense interest because of several major advantages over current optical systems, including their erasable/rewritable capability, high resolution, and high sensitivity. This work …

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Frequency Distribution Of Pyroxene Types And A Method To Separate The Composition Of Multiple Pyroxenes In A Sample, Jimmy Allen Davis Jan 2007

Frequency Distribution Of Pyroxene Types And A Method To Separate The Composition Of Multiple Pyroxenes In A Sample, Jimmy Allen Davis

Electronic Theses and Dissertations

Determining mafic mineral composition of asteroid bodies is a topic reviewed by M.J. Gaffey et al. (2002). The iterative procedure discussed can be implemented as an algorithm, and such efforts revealed weaknesses that are examined in this work. We seek to illustrate the limits of this method and graphically determine its predictions. There are boundaries in the formulae given where the equations break down. In ranges where mafic mixtures are predicted, a method is illustrated that allows a decoupling of these mixtures into the constituents.

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High-Speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems, Wangkuen Lee Jan 2007

High-Speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems, Wangkuen Lee

Electronic Theses and Dissertations

1.55-µm high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (>5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied …

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Effect Of Inner Scale Atmospheric Spectrum Models On Scintillation In All Optical Turbulence Regimes, Kenneth Mayer Jan 2007

Effect Of Inner Scale Atmospheric Spectrum Models On Scintillation In All Optical Turbulence Regimes, Kenneth Mayer

Electronic Theses and Dissertations

Experimental studies have shown that a "bump" occurs in the atmospheric spectrum just prior to turbulence cell dissipation.1,3,4 In weak optical turbulence, this bump affects calculated scintillation. The purpose of this thesis was to determine if a "non-bump" atmospheric power spectrum can be used to model scintillation for plane waves and spherical waves in moderate to strong optical turbulence regimes. Scintillation expressions were developed from an "effective" von Karman spectrum using an approach similar to that used by Andrews et al.8,14,15 in developing expressions from an "effective" modified (bump) spectrum. The effective spectrum extends the Rytov approximation into all optical …

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Infrared Antenna-Coupled Phased-Array, Christopher Middlebrook Jan 2007

Infrared Antenna-Coupled Phased-Array, Christopher Middlebrook

Electronic Theses and Dissertations

Phased-array antennas are commonplace in the radiofrequency portion of the electromagnetic spectrum. Exploitation of phasing effects between multiple antennas facilitates a wide range of applications, including synthetic-aperture radar, beam forming, and beam scanning. For the first time, the phased addition of multiple dipole antennas is demonstrated in the infrared, at a wavelength of 10.6 micrometers. Coplanar strip lines are used to interconnect the antennas, preserving the phase of the individual contributions. Several different proof-of-concept experiments are performed, using planar antennas fabricated with direct-write electron-beam lithography. Infrared-frequency currents from two dipole antennas are summed together at a common feedpoint and dissipated …

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Soliton Solutions Of Nonlinear Partial Differential Equations Using Variational Approximations And Inverse Scattering Techniques, Thomas Vogel Jan 2007

Soliton Solutions Of Nonlinear Partial Differential Equations Using Variational Approximations And Inverse Scattering Techniques, Thomas Vogel

Electronic Theses and Dissertations

Throughout the last several decades many techniques have been developed in establishing solutions to nonlinear partial differential equations (NPDE). These techniques are characterized by their limited reach in solving large classes of NPDE. This body of work will study the analysis of NPDE using two of the most ubiquitous techniques developed in the last century. In this body of work, the analysis and techniques herein are applied to unsolved physical problems in both the fields of variational approximations and inverse scattering transform. Additionally, a new technique for estimating the error of a variational approximation is established. Note that the material …

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Bluetooth-Base Worm Modeling And Simulation, Haiou Xiang Jan 2007

Bluetooth-Base Worm Modeling And Simulation, Haiou Xiang

Electronic Theses and Dissertations

Bluetooth is one of the most popular technologies in the world in the new century. Meanwhile it attracts attackers to develop new worm and malicious code attacking Bluetooth wireless network. So far the growth of mobile malicious code is very fast and they have become a great potential threat to our society. In this thesis, we study Bluetooth worm in Mobile Wireless Network. Firstly we investigate the Bluetooth technology and several previously appeared Bluetooth worms, e.g. "Caribe","Comwar", and we find the infection cycle of a Bluetooth worm. Next, we develop a new simulator, Bluetooth Worm simulator (BTWS), which simulates Bluetooth …

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Model Studies Of Time-Dependent Ducting For High-Frequency Gravity Waves And Associated Airglow Responses In The Upper Atmospher, Yonghui Yu Jan 2007

Model Studies Of Time-Dependent Ducting For High-Frequency Gravity Waves And Associated Airglow Responses In The Upper Atmospher, Yonghui Yu

Electronic Theses and Dissertations

This doctoral dissertation has mainly concentrated on modeling studies of shorter period acoustic-gravity waves propagating in the upper atmosphere. Several cases have been investigated in the literature, which are focusing on the propagation characteristics of high-frequency gravity wave packets. The dissertation consists of five main divisions of which each has its own significance to be addressed, and these five chapters are also bridged in order with each other to present a theme about gravity wave ducting dynamics, energetics, and airglows. The first chapter is served as an introduction of the general topic about atmospheric acoustic-gravity waves. Some of the historical …

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Micro-Optic-Spectral-Spatial-Elements (Mosse), Alok Ajay Mehta Jan 2007

Micro-Optic-Spectral-Spatial-Elements (Mosse), Alok Ajay Mehta

Electronic Theses and Dissertations

Over a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization gratings. The feasibility of fabrication, functionality, and level of integration which these elements can be used in an optical system differentiate which elements are more compatible with certain systems than others. With enabling technologies emerging allowing …

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Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad Jan 2007

Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad

Electronic Theses and Dissertations

Running critical applications, such as e-commerce, in a distributed environment requires assurance of the identities of the participants communicating with each other. Providing such assurance in a distributed environment is a difficult task. The goal of a security protocol is to overcome the vulnerabilities of a distributed environment by providing a secure way to disseminate critical information into the network. However, designing a security protocol is itself an error-prone process. In addition to employing an authentication protocol, one also needs to make sure that the protocol successfully achieves its authentication goals. The Distributed Temporal Protocol Logic (DTPL) provides a language …

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Surface Characterization Of Thin Film Zno Capacitors By Capacitance-Voltage Measurements, Linda Smith Jan 2007

Surface Characterization Of Thin Film Zno Capacitors By Capacitance-Voltage Measurements, Linda Smith

Electronic Theses and Dissertations

The main objective of the research was the fabrication and characterization of MOS/MIS capacitors with ZnO as the insulating layer. Comparison with the already well known behavior of MOS/MIS capacitors with SiO2 as insulator was used to facilitate determination of the ZnO characteristics. Moreover, thermal annealing of the samples led to increased understanding of the role of defects on the dielectric properties of the ZnO layers in the MOS/MIS devices. Hall-effect transport measurements and x-ray diffraction (XRD) spectroscopy are used to analyze the structure and electronic surface characteristics of the ZnO insulator. Capacitance-voltage (C-V) measurements are used to understand the …

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Influence Of Electron Trapping On Minority Carrier Transport Properties Of Wide Band Gap Semiconductors, Olena Tirpak Jan 2007

Influence Of Electron Trapping On Minority Carrier Transport Properties Of Wide Band Gap Semiconductors, Olena Tirpak

Electronic Theses and Dissertations

Minority carrier transport properties and the effects of electron irradiation/injection were studied in GaN and ZnO containing dopants known to form acceptor states deep within the materials' bandgap. Minority carrier diffusion length and lifetime changes were investigated using Electron Beam Induced Current (EBIC) method, cathodoluminescence spectroscopy, spectral photoresponse and persistent photoconductivity measurements. It is shown that electron irradiation by the beam of a scanning electron microscope results in a significant increase of minority carrier diffusion length. These findings are supported by the cathodoluminescence measurements that demonstrate the decay of near-band-edge intensity as a consequence of increasing carrier lifetime under continuous …

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Hybrid Photonic Signal Processing, Farzan Naseer Ghauri Jan 2007

Hybrid Photonic Signal Processing, Farzan Naseer Ghauri

Electronic Theses and Dissertations

This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an …

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Rigorous Analysis Of Wave Guiding And Diffractive Integrated Optical Structures, Andrew Greenwell Jan 2007

Rigorous Analysis Of Wave Guiding And Diffractive Integrated Optical Structures, Andrew Greenwell

Electronic Theses and Dissertations

The realization of wavelength scale and sub-wavelength scale fabrication of integrated optical devices has led to a concurrent need for computational design tools that can accurately model electromagnetic phenomena on these length scales. This dissertation describes the physical, analytical, numerical, and software developments utilized for practical implementation of two particular frequency domain design tools: the modal method for multilayer waveguides and one-dimensional lamellar gratings and the Rigorous Coupled Wave Analysis (RCWA) for 1D, 2D, and 3D periodic optical structures and integrated optical devices. These design tools, including some novel numerical and programming extensions developed during the course of this work, …

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An Examination Of The Effectiveness Of The Adomian Decomposition Method In Fluid Dynamic Applications, Sonia Holmquist Jan 2007

An Examination Of The Effectiveness Of The Adomian Decomposition Method In Fluid Dynamic Applications, Sonia Holmquist

Electronic Theses and Dissertations

Since its introduction in the 1980's, the Adomian Decomposition Method (ADM) has proven to be an efficient and reliable method for solving many types of problems. Originally developed to solve nonlinear functional equations, the ADM has since been used for a wide range of equation types (like boundary value problems, integral equations, equations arising in flow of incompressible and compressible fluids etc...). This work is devoted to an evaluation of the effectiveness of this method when used for fluid dynamic applications. In particular, the ADM has been applied to the Blasius equation, the Falkner-Skan equation, and the Orr-Sommerfeld equation. This …

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Towards A Self-Calibrating Video Camera Network For Content Analysis And Forensics, Imran Junejo Jan 2007

Towards A Self-Calibrating Video Camera Network For Content Analysis And Forensics, Imran Junejo

Electronic Theses and Dissertations

Due to growing security concerns, video surveillance and monitoring has received an immense attention from both federal agencies and private firms. The main concern is that a single camera, even if allowed to rotate or translate, is not sufficient to cover a large area for video surveillance. A more general solution with wide range of applications is to allow the deployed cameras to have a non-overlapping field of view (FoV) and to, if possible, allow these cameras to move freely in 3D space. This thesis addresses the issue of how cameras in such a network can be calibrated and how …

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Efficient Inversion Of The Cone Beam Transform For A General Class Of Curves, Mikhail Kapralov Jan 2007

Efficient Inversion Of The Cone Beam Transform For A General Class Of Curves, Mikhail Kapralov

Electronic Theses and Dissertations

We extend an efficient cone beam transform inversion formula, proposed earlier for helices, to a general class of curves. The conditions that describe the class are very natural. Curves C are smooth, without self-intersections, have positive curvature and torsion, do not bend too much in a certain sense, and do not admit lines which are tangent to C at one point and intersect C at another point. A domain U is found where reconstruction is possible with a filtered backprojection type algorithm. Results of numerical experiments demonstrate very good image quality. The algorithm developed is useful for image reconstruction in …

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Pade Approximants And One Of Its Applications, Tame-Kouontcho Fowe Jan 2007

Pade Approximants And One Of Its Applications, Tame-Kouontcho Fowe

Electronic Theses and Dissertations

This thesis is concerned with a brief summary of the theory of Pade approximants and one of its applications to Finance. Proofs of most of the theorems are omitted and many developments could not be mentioned due to the vastness of the field of Pade approximations. We provide reference to research papers and books that contain exhaustive treatment of the subject. This thesis is mainly divided into two parts. In the first part we derive a general expression of the Pade approximants and some of the results that will be related to the work on the second part of the …

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High Birefringence Liquid Crystals For Optical Communications, Amanda Jane Parish Jan 2007

High Birefringence Liquid Crystals For Optical Communications, Amanda Jane Parish

Electronic Theses and Dissertations

High birefringence (Δn > 0.4) nematic liquid crystals are particularly attractive for infrared applications because they enable a thinner cell gap to be used for achieving fast response time and improved diffraction efficiency. In this thesis, the mesomorphic and electro‐optic properties of several new fluorinated isothiocyanate (NCS) terphenyl and phenyl tolane single compounds and mixtures are reported. The single compounds demonstrated Δn~0.35‐0.52 in the visible spectral region at room temperature and exhibit relatively low viscosity. It was found that lateral fluorine substitutions and short alkyl chains eliminate smectic phase and lower the melting temperature of the single compounds. However, the consequence …

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Forensic Analysis Of C-4 And Commercial Blasting Agents For Possible Discrimination, Katie Steele Jan 2007

Forensic Analysis Of C-4 And Commercial Blasting Agents For Possible Discrimination, Katie Steele

Electronic Theses and Dissertations

The criminal use of explosives has increased in recent years. Political instability and the wide spread access to the internet, filled with "homemade recipes," are two conjectures for the increase. C-4 is a plastic bonded explosive (PBX) comprised of 91% of the high explosive RDX, 1.6% processing oils, 5.3% plasticizer, and 2.1% polyisobutylene (PIB). C-4 is most commonly used for military purposes, but also has found use in commercial industry as well. Current methods for the forensic analysis of C-4 are limited to identification of the explosive; however, recent publications have suggested the plausibility of discrimination between C-4 samples based …

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Stability And Preservation Properties Of Multisymplectic Integrators, Tomasz Wlodarczyk Jan 2007

Stability And Preservation Properties Of Multisymplectic Integrators, Tomasz Wlodarczyk

Electronic Theses and Dissertations

This dissertation presents results of the study on symplectic and multisymplectic numerical methods for solving linear and nonlinear Hamiltonian wave equations. The emphasis is put on the second order space and time discretizations of the linear wave, the Klein-Gordon and the sine-Gordon equations. For those equations we develop two multisymplectic (MS) integrators and compare their performance to other popular symplectic and non-symplectic numerical methods. Tools used in the linear analysis are related to the Fourier transform and consist of the dispersion relationship and the power spectrum of the numerical solution. Nonlinear analysis, in turn, is closely connected to the temporal …

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Categorical Properties Of Lattice-Valued Convergence Spaces, Paul Flores Jan 2007

Categorical Properties Of Lattice-Valued Convergence Spaces, Paul Flores

Electronic Theses and Dissertations

This work can be roughly divided into two parts. Initially, it may be considered a continuation of the very interesting research on the topic of Lattice-Valued Convergence Spaces given by Jager [2001, 2005]. The alternate axioms presented here seem to lead to theorems having proofs more closely related to standard arguments used in Convergence Space theory when the Lattice is L = f0; 1g:Various Subcategories are investigated. One such subconstruct is shown to be isomorphic to the category of Lattice Valued Fuzzy Convergence Spaces defined and studied by Jager [2001]. Our principal category is shown to be a topological universe …

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Developing Strand Space Based Models And Proving The Correctness Of The Ieee 802.11i Authentication Protocol With Restricted Sec, Zeeshan Furqan Jan 2007

Developing Strand Space Based Models And Proving The Correctness Of The Ieee 802.11i Authentication Protocol With Restricted Sec, Zeeshan Furqan

Electronic Theses and Dissertations

The security objectives enforce the security policy, which defines what is to be protected in a network environment. The violation of these security objectives induces security threats. We introduce an explicit notion of security objectives for a security protocol. This notion should precede the formal verification process. In the absence of such a notion, the security protocol may be proven correct despite the fact that it is not equipped to defend against all potential threats. In order to establish the correctness of security objectives, we present a formal model that provides basis for the formal verification of security protocols. We …

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Maya Eclipses: Modern Data, The Triple Tritos And The Double Tzolkin, William Earl Beck Jan 2007

Maya Eclipses: Modern Data, The Triple Tritos And The Double Tzolkin, William Earl Beck

Electronic Theses and Dissertations

The Eclipse Table, on pages 51-58, of the Dresden Codex has long fascinated Maya scholars. Researchers use the mean-value method of 173.3 days to determine nodal passage that is the place where eclipses can occur. These studies rely on Oppolzer's Eclipse Canon and Schram's Moon Phase Tables to verify eclipse occurrences. The newer canons of Jean Meeus and Bao-Lin Liu use decimal accuracy. What would be the effect of modern astronomical data on the previous studies and the Maya Eclipse Table? The study utilizes a general view of eclipses that includes eclipses not visible to the Maya. Lunar eclipses are …

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Augmentation In Visual Reality (Avr), Yunjun Zhang Jan 2007

Augmentation In Visual Reality (Avr), Yunjun Zhang

Electronic Theses and Dissertations

Human eyes, as the organs for sensing light and processing visual information, enable us to see the real world. Though invaluable, they give us no way to "edit" the received visual stream or to "switch" to a different channel. The invention of motion pictures and computer technologies in the last century enables us to add an extra layer of modifications between the real world and our eyes. There are two major approaches to modifications that we consider here, offline augmentation and online augmentation. The movie industry has pushed offline augmentation to an extreme level; audiences can experience visual surprises that …

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Outlet Glacier Dynamics In East Greenland And East Antarctica, Leigh Asher Stearns Jan 2007

Outlet Glacier Dynamics In East Greenland And East Antarctica, Leigh Asher Stearns

Electronic Theses and Dissertations

Ice mass from the interior of Greenland and Antarctica is transported to the ocean by numerous large, fast-flowing outlet glaciers. Changes in the flow configuration of these outlet glaciers modulate ice sheet mass balance and sea level. Several recent studies have highlighted rapid increases in glacier speed in both Greenland and Antarctica, implying that the near-term contribution to sea level from ice sheets is under-estimated by current models. Here, the mass balance and force budget of several large outlet glaciers in East Greenland and East Antarctica are investigated using remote-sensing and field-based measurements. Recent estimates show that Greenland’s contribution to …

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Spectroscopic Studies Of Laser Plasmas For Euv Sources, Simi A. George Jan 2007

Spectroscopic Studies Of Laser Plasmas For Euv Sources, Simi A. George

Electronic Theses and Dissertations

With the availability of high reflectivity multilayer mirrors and zone plate lenses, the EUV region (5nm - 40nm) of the electromagnetic spectrum is currently being explored for applications of nanoscale printing and imaging. Advances made in this area have consequences for many areas of science. Research for producing a compact, bright EUV source for laboratory use has gained momentum in recent years. For this study, EUV radiation is produced by irradiating target materials using a focused laser beam. Focused laser beam ionizes the target to create a hot, dense, pulsed plasma source, where emission is a result of the relaxation …

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Multi-View Geometric Constraints For Human Action Recognition And Tracking, Alexei Gritai Jan 2007

Multi-View Geometric Constraints For Human Action Recognition And Tracking, Alexei Gritai

Electronic Theses and Dissertations

Human actions are the essence of a human life and a natural product of the human mind. Analysis of human activities by a machine has attracted the attention of many researchers. This analysis is very important in a variety of domains including surveillance, video retrieval, human-computer interaction, athlete performance investigation, etc. This dissertation makes three major contributions to automatic analysis of human actions. First, we conjecture that the relationship between body joints of two actors in the same posture can be described by a 3D rigid transformation. This transformation simultaneously captures different poses and various sizes and proportions. As a …

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