Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Entire DC Network
Robust Subspace Estimation Using Low-Rank Optimization. Theory And Applications In Scene Reconstruction, Video Denoising, And Activity Recognition., Omar Oreifej
Electronic Theses and Dissertations
In this dissertation, we discuss the problem of robust linear subspace estimation using low-rank optimization and propose three formulations of it. We demonstrate how these formulations can be used to solve fundamental computer vision problems, and provide superior performance in terms of accuracy and running time. Consider a set of observations extracted from images (such as pixel gray values, local features, trajectories . . . etc). If the assumption that these observations are drawn from a liner subspace (or can be linearly approximated) is valid, then the goal is to represent each observation as a linear combination of a compact …
On The Use Of Gaussian Filter Functions For Adaptive Optics, Merfit Assad
On The Use Of Gaussian Filter Functions For Adaptive Optics, Merfit Assad
Electronic Theses and Dissertations
For adaptive optic systems, the use of aperture filter functions calculated using various Zernike modes can be useful in removing lower-order aberrations caused by atmospheric turbulence. Traditionally, these filter functions are calculated using the step function depicting a hard aperture that introduces integrals that are sometimes difficult to integrate and must be done numerically. The Gaussian method can be used in place of the conventional method for calculating the aperture filter functions. Evaluation of the Gaussian approximation for modeling a finite receiver aperture can be made by comparison of reduction in phase variance with results achieved using the conventional method. …
Effects Of Atmospheric Turbulence On The Propagation Of Flattened Gaussian Optical Beams, Doris Cowan
Effects Of Atmospheric Turbulence On The Propagation Of Flattened Gaussian Optical Beams, Doris Cowan
Electronic Theses and Dissertations
In an attempt to mitigate the effects of the atmosphere on the coherence of an optical (laser) beam, interest has recently been shown in changing the beam shape to determine if a different power distribution at the transmitter will reduce the effects of the random fluctuations in the refractive index. Here, a model is developed for the field of a flattened Gaussian beam as it propagates through atmospheric turbulence, and the resulting effects upon the scintillation of the beam and upon beam wander are determined. A comparison of these results is made with the like effects on a standard TEM00 …
Fade Statistics For A Lasercom System And The Joint Pdf Of A Gamma-Gamma Distributed Irradiance And Its Time Derivative, Frida Stromqvist Vetelino
Fade Statistics For A Lasercom System And The Joint Pdf Of A Gamma-Gamma Distributed Irradiance And Its Time Derivative, Frida Stromqvist Vetelino
Electronic Theses and Dissertations
The performance of lasercom systems operating in the atmosphere is reduced by optical turbulence, which causes irradiance fluctuations in the received signal. The result is a randomly fading signal. Fade statistics for lasercom systems are determined from the probability density function (PDF) of the irradiance fluctuations. The expected number of fades per second and their mean fade time require the joint PDF of the fluctuating irradiance and its time derivative. Theoretical integral expressions, as well as closed form, analytical approximations, were developed for the joint PDF of a gamma-gamma distributed irradiance and its time derivative, and the corresponding expression for …
Phase Statistics For A Lightwave Traveling Through Turbulent Media, Donald J. Link
Phase Statistics For A Lightwave Traveling Through Turbulent Media, Donald J. Link
Retrospective Theses and Dissertations
A probability density function is developed for the phase of light that is the result of adding a signal to noise with K-distributed amplitude and uniform phase. The probability density function of the phase associated with the I-K distribution is also developed. In the process of deriving the probability density function of the phase much I as learned about the relationships between different probability density functions. Three different methods of deriving homodyned K statistics are shown to be equivalent. Two different methods of deriving I-K statistics are shown to be equivalent. Theoretical moments of the homodyned K distribution are compared …