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 20 of 36 for “"defocusing"”.
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Application of Defocusing Technique to Bubble Depth Measurement
The thesis presents a defocusing technique to extract bubble depth information. Typically, when a bubble is out of focus in an image, the bubble is ignored by applying a filter or thresholding. However, it is known that a bubble image becomes blurred as the bubble moves away from the focal plane. …
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Electron Generations and Transportation in Fast Ignition Experiments
… cone-wire target, with various degrees of laser defocusing. Diagnostics also included electron energy spectra with electron energies between 1MeV to 8MeV using image plates as detectors and found the relevant relativistic maxwellian temperature for each energy curve associated with different …
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Surface wave propagation in 3-D anelastic media
… For amplitude perturbations, elastic focusing/defocusing effects associated with 3-D wave speed structures are dominant while energy dissipation is important in short-period (~ 50 s) surface waves but decreases quickly with increasing wave period. Anelastic focusing/defocusing associated with …
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Nonlinear dispersive equations with random initial data
In the first part of this thesis we consider the defocusing nonlinear wave equation of power-type on R3. We establish an almost sure global existence result with respect to a suitable randomization of the initial data. In particular, this provides examples of initial data of supercritical …
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Limits of High Harmonic Generation conversion efficiency
… propagation effects, such as plasma defocusing and losses due to electron-neutral inverse bremsstrahlung. These phenomena change the phase matching along propagation, resulting in non-coherent harmonic generation and consequently poor efficiencies. We further study ways to mitigate …
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Infinite derivative gravity : a ghost and singularity-free theory
… is employed in order to describe the ghost-free, defocusing behaviour around both Minkowski and de Sitter spacetimes, in the linearised regime.
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Transonic thermal blooming
… become infinite (i.e. "catastrophic" defocusing) as the Mach number approaches unity. However, the nonlinearities in the transonic equations cutoff the trend to infinity, and the values of the flow perturbation quantities are finite. The nonlinear equations with heat addition are …
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On the Role of Linear Processes in the Development and Evolution of Filaments in Air
… order nonlinearities such as plasma induced defocusing and absorption.This work examines the role that linear processes combined with initial spatial and temporal conditioningplay in the generation and subsequent evolution of filaments within nonlinearbeams. It is demonstrated that, because …
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Bounds on the growth of high Sobolev norms of solutions to nonlinear Schrödinger equations
… Sobolev norms of the completely integrable defocusing cubic NLS on the real line.
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Self-similar singularity formation and wellposedness theory for compressible fluids and dispersive PDE
… singularity formation for some supercritical defocusing NLS equations, using its hydrodynamical formulation. The third part of the thesis consists of the study of a different dispersive equation: the Zakharov– Kuznetsov equation. The equation is a generalization of the KdV equation to higher …
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Seismic attenuation of regional phases in the northern Middle East and the Tibetan Plateau
… observed, which is probably related to focusing/defocusing or crustal anisotropy. Intrinsic attenuation could be isolated by solving the inverse problems involving the effects of azimuthal anisotropy and small-scale scattering. Such intrinsic attenuation calculated from regional seismic phase has …
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Multichannel Methods for Restoration in Computed Imaging
… methods implicitly rely on the multichannel defocusing model of SAR autofocus to form well-focused restorations. Utilizing the multichannel structure of the SAR autofocus problem explicitly, we develop a new noniterative restoration approach termed the MultiChannel Autofocus (MCA) algorithm. …
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Modeling and Analysis of Plasma-Assisted Etching Reactor Phenomena
… scheme. Gas-phase ion scattering and ion defocusing owing to local, lateral electric field forces in the near-cavity region, resulted in loss of etch anisotropy even in the absence of chemical (spontaneous) etching. The formation of curved trench sidewalls was accompanied by a decrease in …
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Natural carbonaceous materials for use in transparent Joule heaters
… conductivity. First the power and then the z-defocusing of the laser were varied, and the ability of the resulting films to heat was tested with an applied voltage. To test the conductivity and heating capabilities of the annealed SCT films, 60 volts were applied, the current measured, and the …
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A General Study of the Complex Ginzburg-Landau Equation
… demonstrated in systems with either focusing and defocusing spiral waves, and the related aging exponents, as well as the auto-correlation exponents, are numerically determined. I also investigated nucleation processes when the system is transiting from a turbulent state to the ``frozen'' state. …
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Optical Filaments and Gas Dynamics in Air
… diffraction, Kerr self-focusing and plasma defocusing. This has led to the development of different theories surrounding the generation and persistence of optical filaments propagating over many Rayleigh lengths in air. These theories include wave-guiding model, moving focus model, dynamic …
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Magnetostatic Modelling and Measurement for Particle Dynamics of a Magnetic Energy Filter
… center focusing quadrupole at 0.229 A, and the defocusing quadrupoles at −0.256 A. For the RF electron gun, the dipole current was found to be 4.88 A, with the corresponding quadrupole currents at 1.37 A, 1.61 A, and 1.80 A. Both configurations successfully achieved a reduction in the momentum …
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A grammatical and pragmatic analysis of English passives in second language acquisition
… prominence, abrupt topic shift, and violation of defocusing) and affective functional errors. The results show that affective functional errors outnumber discourse functional errors. These results are accounted for in terms of not only language transfer and but also a socio-cultural factor, …
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Intensyvių femtosekundinių šviesos bangų paketų sklidimo Kero terpėse laikinis ir erdvinis charakterizavimas /
… and and negative change associated with plasma defocusing. Free electron density in the plasma channel was determined. The obtained data may help to estimate laser-induced long-term structural changes in the material and may be applied for fabrication of various microoptical elements in bulk …
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