Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"Nonlinear Phase"”.
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A new technique to reduce phase distortion of recursive filters for video and image processing
… On the other hand, IIR filters have nonlinear phase response as a side effect. This is a major concern in applications such as video and image processing. In this thesis, a new method of preventing artifacts caused by nonlinear phase filtering is introduced. The proposed method, …
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Ultracold quantum gases in one-dimensional optical lattice potentials : nonlinear matter wave dynamics
… potentials our system is described by a discrete nonlinear Schrödinger equation, whose dynamics is determined by the tunneling between adjacent lattice sites and the nonlinear phase evolution. In the main part of this thesis I report on the first experimental observation of nonlinear self-trapping …
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A low phase noise ring oscillator phase-locked loop for wireless applications
… of a 900MHz [Sigma][Detta] ring oscillator based phase-locked loop using 0.35[mu]m technology. Multiple phase noise theories are considered giving insight into low phase-noise voltage controlled oscillator design. The circuit utilizes a fully symmetric differential voltage controlled oscillator …
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Digital equalization techniques for the compensation of nonlinear impairments in long-haul coherent optical communication systems
… operating at 40 Gb/s using Differential Phase Shift Keying (DPSK) revolutionized the field of fiber-optic communications because it provided superior spectral efficiency compared to the state-of-the-art binary intensity-modulation direct-detection receivers. A precursor to this …
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Study of directional ocean wavefield evolution and rogue wave occurrence using large-scale phase-resolved nonlinear simulations
… complex dynamic processes involved, including nonlinear wave interaction, wave breaking and wind forcing, and also wave interactions with currents and bottom bathymetry. With fast computational algorithms for nonlinear phase-resolved wave simulations and modern computational capabilities, we …
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Radar detection and identification of human signatures using moving platforms
… techniques assume a linear variation in target phase over the aperture, whereas human targets have a highly nonlinear phase history. The resulting phase mismatch causes significant SNR loss in the detector itself. In this work, human target modeling is used to derive a more accurate non-linear …
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Fast Chirped Signals for a TDMA Ultrasonic Indoor Positioning System
… frequency of ultrasonic signals is presented. Nonlinear phase characteristics of ultrasonic transducers introduce a frequency deviation in ultrasonic signals. By sweeping at very fast rates, a large spike in the deviation is introduced. The artefacts observable in instantaneous frequency …
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Nonlinear Optics in III-V Quaternary Semiconductor Waveguides
… there is still lack of data in literature on nonlinear optical properties of these materials. In this thesis, we extend the quest to evaluate more candidates from this class of semiconductors. Moreover, we are aiming for demonstrating the potentials of various III-V compounds for nonlinear …
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Quantum noise propagation in nonlinear optical media
… limit the generation of squeezed radiation in nonlinear materials. In the first part of this dissertation a general quantum optical model is developed from fundamental principles to describe optical propagation in a broad variety of nonlinear media. The central distinction of the resulting …
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Continuum Kinetic Simulations of Plasma Sheaths and Instabilities
… and numerical studies of the linear growth and nonlinear saturation of the kinetic Weibel instability, including its role in plasma sheaths. The continuum kinetic algorithm has been shown to compare well with theoretical predictions of Landau damping of Langmuir waves and the two-stream …
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Investigation of High-Nonlinearity Glass Fibers for Potential Applications in Ultrafast Nonlinear Fiber Devices
Nonlinear fiber devices have been attracting considerable attention in recent years, due to their inherent ultrafast response time and potential applications in optical communication systems. They usually require long fibers to generate sufficient nonlinear phase shifts, since nonlinearities of …
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Generalized discrete Fourier transform with non-linear phase : theory and design
… Among these popular transforms, DFT is a linear phase transform and widely used in multicarrier communications due to its performance and fast algorithms. In this thesis, a theoretical framework for Generalized DFT (GDFT) with nonlinear phase exploiting the phase space is developed. It is shown …
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High-Energy YB-Doped Femtosecond Fiber Lasers
… the pulse peak power and spectral bandwidth. The nonlinear transmission coefficient of the saturable absorber is one of the main limitations to achieving high-energy pulses. Throughout my research, I have used two types of saturable absorbers. The first is a lumped semiconductor saturable absorber …
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Measurement of the nonlinear refractive index (n2) and stimulated Raman scattering in optical fibers as a function of germania content, using the photorefractive beam coupling technique
… the understanding and control of optical fiber nonlinearities. While these nonlinearites limit the power handling capacity of optical fibers and can cause noise, signal distortion and cross talk in optically amplified transmission systems, they have been equally harnessed for the development of …
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Broadband Terahertz Signal Generation and Radiation Based on Direct Digital-to-Impulse Radiating Arrays in Silicon
… switch shortly after turning it on. The deep nonlinear switching mechanism results in numerous harmonics from GHz to THz. Based on the high timing accuracy of the radiated THz pulses in D2I, a novel trigger-based beamforming architecture is introduced that enables broadband pulse beamforming …
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Shear flow instabilities in stratified magnetohydrodynamics
… the astrophysically relevant case. Using weakly nonlinear theory, we derive amplitude equations for the two cases of Pe,Rm∼O(1) and Pe,Rm»1, where Pe (the ratio between thermal convection and thermal diffusion) and Rm (the ratio between magnetic induction and magnetic diffusion) denote the Péclet …
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Oscillator Phase Noise Reduction Using Nonlinear Design Techniques
Phase noise from radio frequency (RF) oscillators is one of the major limiting factors affecting communication system performance. Phase noise directly effects short-term frequency stability, Bit-Error-Rate (BER), and phase-locked loop adjacent-channel interference. RF oscillator circuits contain …