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 30 for “"propagating waves"”.
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Vertically propagating waves in a numerical stratospheric model
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979.
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A Dynamical Study of Gravity Waves and Instabilities in the Mesopause Region at Maui, Hawaii
… the interactions between tides and oppositely-propagating waves could explain the observed double-layer structure of large N2/strong wind shear. It is found, using the GROGRAT model, that tidal modulation has two effects on the wave propagation: (1) wave breaking levels descend at a tidal …
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Observation and Interpretation of the Spectra of Atmospheric Gravity Wave Perturbations With Upward and Downward Phase Progressions
… downward phase progression (i.e., upwardly propagating waves). The nightly variances were highly correlated, which suggests that the downward and upward phase perturbations originate from the same low-altitude gravity-wave sources.
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Swimming in slime
… non- Newtonian fluid. We assume that it moves by propagating waves down its length in one direction, creating a thrust and therefore propelling it in the opposite direction. We model the swimmer as an infinite, inextensible waving sheet. We consider two main cases of this swimming sheet problem. …
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Interpretation of equatorial current meter data as internal waves
… frequency-wavenumber energy spectra for internal waves (GM72, GM75, GM79). The GM internal wave models are horizontally isotropic, vertically symmetric, purely propagating, and universal in both time and space. This set of properties effectively eliminates all the interesting physics, since such …
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Studies on Low Frequency Fast Multipole Algorithms
… region around 0.1 wavelength. Evanescent waves and propagating waves are both used to compensate for the accuracy lost in the conventional translation process. The scale invariance of LF-FIPWA is studied in detail to preserve the basic Laplace equation property. To improve the efficiency …
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Efficient mesh truncation techniques for the solution of Maxwell's equations using the finite-difference time domain method
… potential for near reflectionless absorption of propagating waves at the expense of additional layers of absorbing material with twice the number of unknowns as in the interior domain. However, since the PML allows the buffer region between the discontinuity and the termination plane to be …
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Continuum Models of Collective Migration in Living Tissues
… freely on a substrate, our model reproduces the propagating waves of mechanical stress observed in experiments and believed to play a key role in controlling the transmission of information across the tissue and mediating coordinated cell motion. Combining analytical and numerical work we …
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Effects of the chaotic behavior of a superposition of waves in the flux across a channel
… The flow is given by a superposition of two propagating waves. The domain was set up so that a mode-I wave would fit on it, and the perturbation was a mode-4 wave. The experiments were carried out using a grid model with a second-order upwind differencing scheme. Simple Newtonian diffusion …
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Wavelet Analysis and its Application to Modulation Characterization
… the wavelet coefficients are used to decompose propagating waves measured at a single location.
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On the observations of autowaves and avalanches in an aluminum magnesium alloy
… to find the local strain rate field. Propagating waves in the local strain rate were observed in an extended elastoplastic transition during macroscopically uniform deformation before the onset of the Portevin-Le Chatelier effect. The formation of the synchronous oscillations suggests …
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Coupled-waveguide Fabry-Perot resonator
… demultiplexers. The interference of counter propagating waves from reflection by end mirrors and the coupling of waves between the two parallel guides contribute to the operation of this resonator structure. Thus, the device exhibits the attributes of both Fabry-Perot resonator and …
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Problems in cosmology and numerical relativity
… such as the parametric excitation of plasma waves by gravitational waves. This mechanism has been studied in different contexts in the literature, such as the possibility of indirect detection of gravitational waves through electromagnetic signatures of the interaction. In this work, we …
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The functional role of the mammalian tectorial membrane in the cochlear mechanics
… into the mammalian cochlea produce traveling waves that provide the mechanical tuning necessary for spectral decomposition of sound. These traveling waves of motion propagate along the basilar membrane (BM) and ultimately stimulate the mechano-sensory receptors. The tectorial membrane (TM) …
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Quantitative Materials Contrast at High Spatial Resolution With a Novel Near-Field Scanning Microwave Microscope
… to the microwave signals due to evanescent (non-propagating) waves cannot be ignored. I describe different evanescent wave models developed so far to understand the complex tip-to-sample interaction at microwave frequencies. Propagating wave models are also discussed, since they are still …
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Visualisation of chemistry in flow
… imaging was able to probe the bulk behaviour of propagating waves through three-dimensional Taylor vortices but was unable to probe the wave propagation mechanisms. It was found however, that magnetic resonance imaging was able to visualise the behaviour of the chemical waves within the Couette …
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Transient Electromagnetic Waves in Nonlinear Media
… the propagation of transient electromagnetic waves in nonlinear media. It consists of a General Introduction and five scientific papers. The General Introduction gives a broad overview of nonlinear electromagnetic phenomena. The emphasis is on the representation of the constitutive functional …
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Effective development of cylindrical finite-difference time-domain for electromagnetics applications
… (when fully implemented) of absorbing evanescent waves by shifting the frequency poles in the imaginary axis. Such evanescent waves exist in cylindrical structures near the axis of rotation and need to be effectively absorbed if the CFDTD model is to be truncated within this region. Existing CFDTD …
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Features of nonlinear wave-wave and wave-body interactions
Although nonlinear water waves have been the subject of decades of research, there are many problems that remain unsolved, especially in the cases when one or more of the following factors are involved: high-order nonlinear effects, moving boundaries, wavestructure interactions and complicated …
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On intraseasonal variability in the tropics: tropical cyclones, the Madden-Julian Oscillation, and equatorial waves
… is dominated by tropical cyclones, equatorial waves, and the Madden-Julian Oscillation (MJO). Because these phenomena have significant societal impacts on sub-seasonal time scales, and it is important to understand how they interact with the large-scale atmosphere. The first part of this thesis …
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