Effect of modulation maskers on the detection of second-order amplitude modulation with and without notched noise

2006 ◽  
Vol 119 (5) ◽  
pp. 2937-2946 ◽  
Author(s):  
Rosalie M. Uchanski ◽  
Brian C. J. Moore ◽  
Brian R. Glasberg
Keyword(s):  
Amplitude Modulation ◽  
Second Order

scholarly journals Effects of second-order nonstationary cascaded processes on Gaussian beam propagation

1999 ◽  
Vol 17 (1) ◽  
pp. 119-128
Author(s):  
GUIDO TOCI ◽  
MATTEO VANNINI ◽  
RENZO SALIMBENI
Keyword(s):  
Gaussian Beam ◽  
Amplitude Modulation ◽  
Beam Propagation ◽  
Mode Locking ◽  
Second Order ◽  
Light Pulses ◽  
Perturbative Method ◽  
Stationary Conditions ◽  
Finite Aperture ◽  
Propagation Technique

This work proposes an analytical perturbative method describing the effects on the propagation of finite aperture beams due to the self-phase and self-amplitude modulation which result from cascaded second order interaction of ultrashort light pulses. The method merges the semi-analytical solution with a perturbative beam propagation technique, namely the Gaussian Beam Decomposition, which describes the effects of the non linear modulation on the free beam propagation. In particular we have studied the problem of the time- and intensity-dependent transmission of the pulse through slits or apertures placed along the path of the beam simulating a geometry suitable for passive laser mode-locking. Although an efficient pulse shortening action can be obtained in stationary conditions, in non stationary conditions the occurrence of an unavoidable amplitude modulation perturbs the beam propagation and reduces the temporal selectivity of the modulator.

Effect of a noise modulation masker on the detection of second-order amplitude modulation

2003 ◽  
Vol 178 (1-2) ◽  
pp. 1-11 ◽  
Author(s):  
Rebecca E Millman ◽  
Gary G.R Green ◽  
Christian Lorenzi ◽  
Adrian Rees
Keyword(s):  
Amplitude Modulation ◽  
Second Order

Imperfection Sensitivity of Stiffened Cylindrical Shells Under Interactive Buckling

1994 ◽  
Vol 47 (6S) ◽  
pp. S251-S255
Author(s):  
Srinivasan Sridharan
Keyword(s):  
Amplitude Modulation ◽  
Cylindrical Shells ◽  
Computational Modelling ◽  
Local Buckling ◽  
Second Order ◽  
New Technique ◽  
Local Mode ◽  
Imperfection Sensitivity ◽  
Stiffened Shells ◽  
Stiffened Cylindrical Shells

In this paper some recent advances made in the understanding of the phenomena and computational modelling of the interaction of local and overall instabilities in stiffened cylindrical shells will be reviewed. These relate to two distinct categories of problems: (1) Axially compressed stringer-stiffened shells and (2) Ring-stiffened cylinders subjected to hydrostatic compression. The former have been analyzed with a novel methodology which employs finite elements in which the local buckling information is embedded. Comparisons of the results of the new technique with Abaqus - a well established nonlinear analysis program - reveals the validity of the underlying concepts of the new technique and efficacy of the new approach. It is shown, that provided all the key local buckling modes triggered in the interaction are considered and the modulation of local buckling amplitudes is accounted for, it is justifiable to neglect the mixed second order stresses and strains in the analysis. Imperfection-sensitivity of a stringer stiffened cylindrical shell structure is illustrated. In the case ring-stiffened cylinders subjected to hydrostatic pressure, it is shown that the amplitude modulation is the key factor in the interaction; it performs the function of capturing the contributions of several neighboring modes of the same longitudinal description as the fundamental local mode, but with differing circumferential wave numbers. An examination of the potential energy function indicates that the amplitude modulation is solely responsible for the presence of the nonvanishing cubic terms, which are dominant over the quartic terms. Once again, mixed second order fields evaluated with appropriate orthogonality conditions have little influence on the interaction and can be safely neglected. An example of an orthotropic layered shell under coincident and well separated critical stresses is presented.

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