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Showing 1 to 20 of 60 for “"subharmonic"”.
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Subharmonic and Non-Subharmonic Pulsed Control of Thermoacoustic Instabilities: Analysis and Experiment
… experimenters in the field have used pulsed and subharmonic fuel controllers to eliminate these instabilities, but very little investigative work has been done on these controllers. The goal of this work is to explain the mechanism of control behind pulsed controllers. It is shown that the …
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On subharmonic instability in boundary layers
The subharmonic instability in two-dimensional boundary layer on a flat plate is analyzed using the parametric instability model and the resonant triad model. The problems arising from both models are solved numerically using the shooting technique and results are presented. It is found that in the …
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A 60 Ghz Mmic 4x Subharmonic Mixer
… RF downconversion. One of these is to employ a subharmonic mixer. In this case, a lower frequency LO is applied and the RF mixes with a harmonic multiple of the LO signal to produce the desired intermediate frequency (IF). The work presented in this thesis will focus on the development of a GaAs …
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Parametric subharmonic instability of internal gravity wave beams
… internal waves, this so-called parametric subharmonic instability (PSI) has been studied extensively and indeed can lead to breakdown. By contrast, the focus here is on understanding how wave beams with locally conned spatial prole, such as those in the field, may differ, in regard to PSI, …
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The cavitation subharmonic signal : mechanistic source and optimised detection
The cavitation subharmonic signal, emitted at frequency values sub-multiple to that of the acoustic driving, is held to be exclusive to the occurrence of driven bubbles within a host medium. Recently, detection of the subharmonic signal has seen a resurgence of interest, particularly for the …
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Weakly q-Convex Domains and Bounded q-Subharmonic Exhaustion Functions
… bounded weakly q-convex domains with bounded q-subharmonic exhaustion functions. Sufficient conditions for this generalized Diederich-Fornæss index to have a given lower bound are proved. We show this generalized index is positive on bounded weakly q-convex domains with C^3 boundaries. …
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Experiments on subharmonic resonance of the Venice lagoon storm gates
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.
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Theory of subharmonic resonance of storm gates for Venice lagoon
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.
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An Extension of the Denjoy-Carleman-Ahlfors Theorem in Subharmonic Form
Made available in DSpace on 2014-12-09T22:17:10Z (GMT). No. of bitstreams: 1 6406154.pdf: 3932803 bytes, checksum: a1b36659f97a6a9630bfc6fe2584ac8f (MD5) Previous issue date: 1963
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Subharmonic resonance of system having non-linear spring with variable coefficient
Thesis (Sc.D.) Massachusetts Institute of Technology. Dept. of Mechanical Engineering, 1948.
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Temporal and spatial growth of subharmonic disturbances in Falkner-Skan flows
… secondary disturbances of fundamental or subharmonic type, and onset of the turbulent regime. In free flight conditions, subharmonic disturbances are the most amplified. Recent modeling of the subharmonic disturbance as a parametric instability arising from the presence of a finite …
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Bounds on the size of strong subordinates of submartingales and subharmonic functions
… inequalities obtained are also shown to hold for subharmonic functions and their suitably defined subordinates.
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On the Integrability of Derivatives of Holomorphic and M-Subharmonic Inner Functions In the Unit Ball of Cn
<p>Let Bn be the unit ball in Cn. If f is a bounded holomorphic function, we say that f is inner provided that its modulus has a radial limit of 1 almost everywhere on Sn where Sn is the unit sphere.</p> <p>If a > -1 and p > 0 then Apa denotes the weighted Bergman space of all holomorphic functions …
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Secondary instabilities of boundary layers
Several aspects of the subharmonic instability of boundary layers are studied. First, the subharmonic instability of incompressible flows over a flat plate is investigated using the resonant triad model and the Floquet model. The primary wave is taken in the form of a two-dimensional (2-0) …
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High-Frequency Ultrasound Drug Delivery and Cavitation
… shown to correspond with the appearance of the subharmonic signal in the acoustic spectrum. Additionally, drug release was found to correlate with increase in subharmonic emission. No evidence of drug release or of the subharmonic signal was detected at 500 kHz. These findings confirmed the role …
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Instabilities of a compressible mixing layer
… evaluated and is found to be negligible. Linear subharmonic Instabilities of a compressible mixing layer, which Is spatially periodic in a translating frame of reference, are analyzed by using Floquet theory. The basic state is obtained by the linear superposition ofa steady mean flow, which is …
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Conformally Flat Spaces of Bounded Curvature
… that if the logarithm of the conformal factor is subharmonic then the space has curvature bounded above by zero, and, subject to a growth constraint, if the logarithm of the conformal factor is subharmonic under all conformal transformations then the curvature is bounded below by zero. If the …
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Studies on secondary instabilities
… Floquet theory, previous analysis looked for subharmonic (wavelength 2 λ) and fundamental (wavelength λ) types of solutions. We extend the Floquet theory to solutions having arbitrary wavelengths, hence including the previous solutions as special cases. Modes with wavelength in between the …
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Wavelet Analysis and its Application to Modulation Characterization
… two most unstable modes, the fundamental and the subharmonic, are also observed in the region of subharmonic growth. In a second application of wavelet analysis, the phase lag of the wavelet coefficients is used to determine the phase relation between the fundamental and the subharmonic in …
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A Reduced-Order Model Bi-Modal Excitation of a Supersonic Planar Jet
… thickness and amplitudes of a fundamental and subharmonic mode to the streamwise location along the jet. Computational fluid dynamics data from the minor plane of a Mach 1.5 heated rectangular jet is used to verify a hyperbolic tangent profile for the mean flow at various streamwise locations. …
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