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Articles 2761 - 2790 of 3529
Full-Text Articles in Physical Sciences and Mathematics
Design, Analysis, And Optimization Of Diffractive Optical Elements Under High Numerical Aperture Focusing, Toufic Jabbour
Design, Analysis, And Optimization Of Diffractive Optical Elements Under High Numerical Aperture Focusing, Toufic Jabbour
Electronic Theses and Dissertations
The demand for high optical resolution has brought researchers to explore the use of beam shaping diffractive optical elements (DOEs) for improving performance of high numerical aperture (NA) optical systems. DOEs can be designed to modulate the amplitude, phase and/or polarization of a laser beam such that it focuses into a targeted irradiance distribution, or point spread function (PSF). The focused PSF can be reshaped in both the transverse focal plane and along the optical axis. Optical lithography, microscopy and direct laser writing are but a few of the many applications in which a properly designed DOE can significantly improve …
Vectorpad: A Tool For Visualizing Vector Operations, Jared Bott
Vectorpad: A Tool For Visualizing Vector Operations, Jared Bott
Electronic Theses and Dissertations
Visualization of three-dimensional vector operations can be very helpful in understanding vector mathematics. However, creating these visualizations using traditional WIMP interfaces can be a troublesome exercise. In this thesis, we present VectorPad, a pen-based application for three-dimensional vector mathematics visualization. VectorPad allows users to define vectors and perform mathematical operations upon them through the recognition of handwritten mathematics. The VectorPad user interface consists of a sketching area, where the user can write vector definitions and other mathematics, and a 3D graph for visualization. After recognition, vectors are visualized dynamically on the graph, which can be manipulated by the user. A …
Design, Synthesis, And Characterization Of Novel Hydrophilic Fluorene-Based Derivatives For Bioimaging Applications, Dao Nguyen
Electronic Theses and Dissertations
In this work, hydrophilic fluorene-based derivatives that contain ethylene oxide substituents, have been synthesized and characterized for potential use as new fluorophores for bioimaging applications and for fluorescence sensing of heavy metals. Symmetrical and unsymmetrical fluorene derivatives based on structural types of acceptor-pi-acceptor, acceptor-pi-donor, and donor-pi-donor were characterized by TGA, UV-vis absorption, fluorescence emission, lifetime, anisotropy, and two-photon absorption (2PA) cross section. They were found to possess high thermal stability, high photostability, high fluorescence quantum yields, and generally large two-photon absorption cross sections, making them quite suitable for new probes in single-photon absorption and two-photon absorption fluorescence microscopy imaging. Novel …
Efficient Cone Beam Reconstruction For The Distorted Circle And Line Trajectory, Souleymane Konate
Efficient Cone Beam Reconstruction For The Distorted Circle And Line Trajectory, Souleymane Konate
Electronic Theses and Dissertations
We propose an exact filtered backprojection algorithm for inversion of the cone beam data in the case when the trajectory is composed of a distorted circle and a line segment. The length of the scan is determined by the region of interest , and it is independent of the size of the object. With few geometric restrictions on the curve, we show that we have an exact reconstruction. Numerical experiments demonstrate good image quality.
Almost Regular Graphs And Edge Face Colorings Of Plane Graphs, Lisa Macon
Almost Regular Graphs And Edge Face Colorings Of Plane Graphs, Lisa Macon
Electronic Theses and Dissertations
Regular graphs are graphs in which all vertices have the same degree. Many properties of these graphs are known. Such graphs play an important role in modeling network configurations where equipment limitations impose a restriction on the maximum number of links emanating from a node. These limitations do not enforce strict regularity, and it becomes interesting to investigate nonregular graphs that are in some sense close to regular. This dissertation explores a particular class of almost regular graphs in detail and defines generalizations on this class. A linear-time algorithm for the creation of arbitrarily large graphs of the discussed class …
Weighted Lp-Stability For Localized Infinite Matrices, Qiling Shi
Weighted Lp-Stability For Localized Infinite Matrices, Qiling Shi
Electronic Theses and Dissertations
This dissertation originates from a classical result that the lp-stability of the convolution operator associated with a summable sequence are equivalent to each other for different p . This dissertation is motivated by the recent result by C. E. Shin and Q. Sun (Journal ofFunctional Analysis, 256(2009), 2417-2439), where the lp-stability of infinite matrices in the Gohberg-Baskakov-Sjostrand class are proved to be equivalent to each other for different p. In the dissertation, for an infinite matrix having certain off-diagonal decay, its weighted lp-stability for different p are proved to be equivalent to each other and hence a result by Shin …
Spin Quantum Dynamics In Molecular Magnets, John Henderson
Spin Quantum Dynamics In Molecular Magnets, John Henderson
Electronic Theses and Dissertations
Molecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are single-molecule magnets (SMMs) and antiferromagnetic (AFM) molecular wheels in which the spin state of the molecule is known to behave quantum mechanically at low temperatures. In previous experiments the dynamics …
Chemical Bath Deposition Of Group Ii-Vi Semiconductor Thin Films For Solar Cells Applications, Hani Khallaf
Chemical Bath Deposition Of Group Ii-Vi Semiconductor Thin Films For Solar Cells Applications, Hani Khallaf
Electronic Theses and Dissertations
Chemical bath deposition (CBD) is the analog in liquid phase of the well-known chemical vapor deposition technique in the vapor phase. In CBD, deposition of thin films takes place from aqueous solutions at low temperatures by a chemical reaction between dissolved precursors, with the help of a complexing agent. Among all techniques used to grow Group II-VI semiconductors, CBD has the advantage of being a simple, low temperature, and inexpensive large-area deposition technique. So far, its contribution in thin film solar cells industry has been mainly limited to growing n-type CdS and/or ZnS window layers for CdTe-based and CIGS-based solar …
Electron Transport In Single Molecule Magnet Transistors And Optical Lambda Transitions In The Nitrogen-Vacancy Center In Diamon, Gabriel Gonzalez
Electron Transport In Single Molecule Magnet Transistors And Optical Lambda Transitions In The Nitrogen-Vacancy Center In Diamon, Gabriel Gonzalez
Electronic Theses and Dissertations
This thesis presents some theoretical studies dealing with quantum interference effects in electron transport through single molecule magnet transistors and a study on optical non-conserving spin transitions in the Nitrogen-vacancy center in diamond. The thesis starts with a brief general introduction to the physics of quantum transport through single electron transistors. Afterwards, the main body of the thesis is divided into three studies: (i) In chapter (2) we describe the properties of single molecule magnets and the Berry phase interference present in this nanomagnets. We then propose a way to detect quantum interference experimentally in the current of a single …
Dense Spectral Beam Combining With Volume Bragg Gratings In Photo-Thermo-Refractive Glass, Oleksiy Andrusyak
Dense Spectral Beam Combining With Volume Bragg Gratings In Photo-Thermo-Refractive Glass, Oleksiy Andrusyak
Electronic Theses and Dissertations
Beam combining techniques have become an important tool in the design of high-power high-brightness laser systems. Spectral beam combining (SBC) is an incoherent combining technique that does not require phase control of sources, allowing for a stable and robust system. Using SBC, beams from an array of lasers with each element operated at a different wavelength are combined into a single near-diffraction-limited beam with the same aperture using dispersive optical elements. SBC by means of volume Bragg gratings (VBGs) utilizes unique spectral response of VBGs: diffraction efficiency is close to unity when the Bragg condition is satisfied and is close …
Analysis And Design Of Wide-Angle Foveated Optical Systems, George Curatu
Analysis And Design Of Wide-Angle Foveated Optical Systems, George Curatu
Electronic Theses and Dissertations
The development of compact imaging systems capable of transmitting high-resolution images in real-time while covering a wide field-of-view (FOV) is critical in a variety of military and civilian applications: surveillance, threat detection, target acquisition, tracking, remote operation of unmanned vehicles, etc. Recently, optical foveated imaging using liquid crystal (LC) spatial light modulators (SLM) has received considerable attention as a potential approach to reducing size and complexity in fast wide-angle lenses. The fundamental concept behind optical foveated imaging is reducing the number of elements in a fast wide-angle lens by placing a phase SLM at the pupil stop to dynamically compensate …
Scheduling And Resource Management For Complex Systems: From Large-Scale Distributed Systems To Very Large Sensor Networks, Chen Yu
Electronic Theses and Dissertations
In this dissertation, we focus on multiple levels of optimized resource management techniques. We first consider a classic resource management problem, namely the scheduling of data-intensive applications. We define the Divisible Load Scheduling (DLS) problem, outline the system model based on the assumption that data staging and all communication with the sites can be done in parallel, and introduce a set of optimal divisible load scheduling algorithms and the related fault-tolerant coordination algorithm. The DLS algorithms introduced in this dissertation exploit parallel communication, consider realistic scenarios regarding the time when heterogeneous computing systems are available, and generate optimal schedules. Performance …
Gold Nanoparticles: Synthesis, Property Study And Applcications For Biomolecular Detection And Photothermal Therapy, Xiong Liu
Electronic Theses and Dissertations
This dissertation presents a systematic study on gold nanoparticles: from their chemical synthesis, modification of surface functionalities, optical properties studies with emphasis on the absorption and scattering properties, to applications of gold nanoparticles in biomolecular detection, imaging and photothermal therapy. In chapter 2, we studied the kinetics of gold nanoparticle growth under Brust-Shiffrin reaction conditions. In chapter 3, we further examined the reaction mechanism and growth kinetics of gold nanoparticles using oleylamine as both a reducing reagent and particle growth passivation ligand. From these two projects, important understanding was revealed on gold nanoparticle formation and growth mechanism. Chapter 4 describes …
Imaging And Spectroscopy Of Conducting Polymer-Fullerene Composite Materials, Daeri Tenery
Imaging And Spectroscopy Of Conducting Polymer-Fullerene Composite Materials, Daeri Tenery
Electronic Theses and Dissertations
Since the development and optical study of conjugated (conducting) polymers it has become apparent that chain conformation and aggregation at the molecular scale result in complex heterogeneous nanostructured bulk materials for which a detailed insight into morphological, spectroscopic as well as optoelectronic properties and mechanisms is overwhelmingly difficult to obtain. Nanoparticles composed of the conjugated polymer poly (MEH-PPV) and nanocomposite nanoparticles consisting of MEH-PPV doped with 1-(3-methoxycarbonylpropyl)-1-phenyl-C61 (PCBM) were prepared as model systems to study these materials at the length scale of one to a few domains. The MEH-PPV and PCBM doped nanoparticles were analyzed by single imaging/particle spectroscopy (SPS) …
Synthesis Of Novel Fluorene-Based Two-Photon Absorbing Molecules And Their Applications In Optical Data Storage, Microfabricatio, Ciceron Yanez
Synthesis Of Novel Fluorene-Based Two-Photon Absorbing Molecules And Their Applications In Optical Data Storage, Microfabricatio, Ciceron Yanez
Electronic Theses and Dissertations
Two-photon absorption (2PA) has been used for a number of scientific and technological applications, exploiting the fact that the 2PA probability is directly proportional to the square of the incident light intensity (while one-photon absorption bears a linear relation to the incident light intensity). This intrinsic property of 2PA leads to 3D spatial localization, important in fields such as optical data storage, fluorescence microscopy, and 3D microfabrication. The spatial confinement that 2PA enables has been used to induce photochemical and photophysical events in increasingly smaller volumes and allowed nonlinear, 2PA-based, technologies to reach sub-diffraction limit resolutions. The primary focus of …
Automatic Graphics And Game Content Generation Through Evolutionary Computation, Erin Hastings
Automatic Graphics And Game Content Generation Through Evolutionary Computation, Erin Hastings
Electronic Theses and Dissertations
Simulation and game content includes the levels, models, textures, items, and other objects encountered and possessed by players during the game. In most modern video games and simulation software, the set of content shipped with the product is static and unchanging, or at best, randomized within a narrow set of parameters. However, ideally, if game content could be constantly and automatically renewed, players would remain engaged longer in the evolving stream of content. This dissertation introduces three novel technologies that together realize this ambition. (1) The first, NEAT Particles, is an evolutionary method to enable users to quickly and easily …
Detecting Malicious Software By Dynamicexecution, Jianyong Dai
Detecting Malicious Software By Dynamicexecution, Jianyong Dai
Electronic Theses and Dissertations
Traditional way to detect malicious software is based on signature matching. However, signature matching only detects known malicious software. In order to detect unknown malicious software, it is necessary to analyze the software for its impact on the system when the software is executed. In one approach, the software code can be statically analyzed for any malicious patterns. Another approach is to execute the program and determine the nature of the program dynamically. Since the execution of malicious code may have negative impact on the system, the code must be executed in a controlled environment. For that purpose, we have …
Attacks On Difficult Instances Of Graph Isomorphism: Sequential And Parallel Algorithms, Greg Tener
Attacks On Difficult Instances Of Graph Isomorphism: Sequential And Parallel Algorithms, Greg Tener
Electronic Theses and Dissertations
The graph isomorphism problem has received a great deal of attention on both theoretical and practical fronts. However, a polynomial algorithm for the problem has yet to be found. Even so, the best of the existing algorithms perform well in practice; so well that it is challenging to find hard instances for them. The most efficient algorithms, for determining if a pair of graphs are isomorphic, are based on the individualization-refinement paradigm, pioneered by Brendan McKay in 1981 with his algorithm nauty. Nauty and various improved descendants of nauty, such as bliss and saucy, solve the graph isomorphism problem by …
Concept Learning By Example Decomposition, Sameer Joshi
Concept Learning By Example Decomposition, Sameer Joshi
Electronic Theses and Dissertations
For efficient understanding and prediction in natural systems, even in artificially closed ones, we usually need to consider a number of factors that may combine in simple or complex ways. Additionally, many modern scientific disciplines face increasingly large datasets from which to extract knowledge (for example, genomics). Thus to learn all but the most trivial regularities in the natural world, we rely on different ways of simplifying the learning problem. One simplifying technique that is highly pervasive in nature is to break down a large learning problem into smaller ones; to learn the smaller, more manageable problems; and then to …
A Preliminary Study Of A Non-Invasive Glucose Sensor Based On A Mercury Sensor, Erin Wood
A Preliminary Study Of A Non-Invasive Glucose Sensor Based On A Mercury Sensor, Erin Wood
Electronic Theses and Dissertations
Diabetes mellitus is a potentially lethal disease that affects 7.6 percent of American people. In the US, it is recognized as the 6th leading cause of death. Failure to control blood glucose levels (BGL) in patients with either type of diabetes can lead to other serious complications as well, such as loss of limb, blindness and other health problems. Controlling and monitoring the BGL in post-op and intensive care patients in the hospital is also vital to their health. Currently the most reliable method of monitoring BGL is through an invasive procedure which monitors the amount of glucose in blood …
Visual Inspection Of Railroad Tracks, Pavel Babenko
Visual Inspection Of Railroad Tracks, Pavel Babenko
Electronic Theses and Dissertations
In this dissertation, we have developed computer vision methods for measurement of rail gauge, and reliable identification and localization of structural defects in railroad tracks. The rail gauge is the distance between the innermost sides of the two parallel steel rails. We have developed two methods for evaluation of rail gauge. These methods were designed for different hardware setups: the first method works with two pairs of unaligned video cameras while the second method works with depth maps generated by paired laser range scanners. We have also developed a method for detection of rail defects such as damaged or missed …
Design And Analysis Of Effective Routing And Channel Scheduling For Wavelength Division Multiplexing Optical Networks, Xingbo Gao
Electronic Theses and Dissertations
Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and …
Modeling Scenes And Human Activities In Videos, Arslan Basharat
Modeling Scenes And Human Activities In Videos, Arslan Basharat
Electronic Theses and Dissertations
In this dissertation, we address the problem of understanding human activities in videos by developing a two-pronged approach: coarse level modeling of scene activities and fine level modeling of individual activities. At the coarse level, where the resolution of the video is low, we rely on person tracks. At the fine level, richer features are available to identify different parts of the human body, therefore we rely on the body joint tracks. There are three main goals of this dissertation: (1) identify unusual activities at the coarse level, (2) recognize different activities at the fine level, and (3) predict the …
Room Temperature Synthesis And Systematic Characterization Of Ultra-Small Ceria Nanoparticles, Chetak Patel
Room Temperature Synthesis And Systematic Characterization Of Ultra-Small Ceria Nanoparticles, Chetak Patel
Electronic Theses and Dissertations
Cerium oxide (ceria, CeOâ‚‚) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus acting as an anti-oxidant. This phenomenon has been explained based on the autocatalytic property of ceria NPs. Several methods have been developed for the synthesis of ceria NPs …
Geometric Invariance In The Analysis Of Human Motion In Video Data, Yuping Shen
Geometric Invariance In The Analysis Of Human Motion In Video Data, Yuping Shen
Electronic Theses and Dissertations
Human motion analysis is one of the major problems in computer vision research. It deals with the study of the motion of human body in video data from different aspects, ranging from the tracking of body parts and reconstruction of 3D human body configuration, to higher level of interpretation of human action and activities in image sequences. When human motion is observed through video camera, it is perspectively distorted and may appear totally different from different viewpoints. Therefore it is highly challenging to establish correct relationships between human motions across video sequences with different camera settings. In this work, we …
The Forensic Analysis Of Triacetone Triperoxide (Tatp) Precursors And Synthetic By-Products, Kimberly Painter
The Forensic Analysis Of Triacetone Triperoxide (Tatp) Precursors And Synthetic By-Products, Kimberly Painter
Electronic Theses and Dissertations
Triacetone Triperoxide (TATP) is a primary high explosive that can be synthesized using commercially available starting materials and has grown in use among terrorists over the past several years. Additives present in the precursors were investigated to see if they carry through the TATP synthesis and can be detected in the final product potentially aiding in the identification of the source. Additives identified in the acetones were also identified in pre-blast and in some post-blast samples. However, these additives are present in trace quantities relative to the TATP, which coupled with the volatility and short lifetimes of some of the …
Standing Waves Of Spatially Discrete Fitzhugh-Nagumo Equations, Joseph Segal
Standing Waves Of Spatially Discrete Fitzhugh-Nagumo Equations, Joseph Segal
Electronic Theses and Dissertations
We study a system of spatially discrete FitzHugh-Nagumo equations, which are nonlinear differential-difference equations on an infinite one-dimensional lattice. These equations are used as a model of impulse propagation in nerve cells. We employ McKean's caricature of the cubic as our nonlinearity, which allows us to reduce the nonlinear problem into a linear inhomogeneous problem. We find exact solutions for standing waves, which are steady states of the system. We derive formulas for all 1-pulse solutions. We determine the range of parameter values that allow for the existence of standing waves. We use numerical methods to demonstrate the stability of …
Synthesis Of Biocompatible Antioixidant Polymer Coated Cerium Oxide Nanoparticles, Its Oxidase Like Behavior And Cellular Uptake, Atul Asati
Electronic Theses and Dissertations
Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant …
The Sheffer B-Type 1 Orthogonal Polynomial Sequences, Daniel Galiffa
The Sheffer B-Type 1 Orthogonal Polynomial Sequences, Daniel Galiffa
Electronic Theses and Dissertations
In 1939, I.M. Sheffer proved that every polynomial sequence belongs to one and only one type. Sheffer extensively developed properties of the B-Type 0 polynomial sequences and determined which sets are also orthogonal. He subsequently generalized his classification method to the case of arbitrary B-Type k by constructing the generalized generating function A(t)exp[xH1(t) + · · · + xk+1Hk(t)] = ∑∞n=0 Pn(x)tn, with Hi(t) = hi,iti + hi,i+1t i+1 + · · · , h1,1 ≠ 0. Although extensive research has been done on characterizing polynomial sequences, no analysis has yet been completed on sets of type one or higher …
Optimal Dual Frames For Erasures And Discrete Gabor Frames, Jerry Lopez
Optimal Dual Frames For Erasures And Discrete Gabor Frames, Jerry Lopez
Electronic Theses and Dissertations
Since their discovery in the early 1950's, frames have emerged as an important tool in areas such as signal processing, image processing, data compression and sampling theory, just to name a few. Our purpose of this dissertation is to investigate dual frames and the ability to find dual frames which are optimal when coping with the problem of erasures in data transmission. In addition, we study a special class of frames which exhibit algebraic structure, discrete Gabor frames. Much work has been done in the study of discrete Gabor frames in Rn, but very little is known about the l2(Z) …