Biomedical subjects

A Alippi

Publications and source records attributed to A Alippi.

8 recordsLinked to original sources

PubMed2002

Self-interference between forward and backward propagating parts of a single acoustic plate mode.

Near and far fields of a particular (S(1)) Lamb mode, generated on a steel plate by means of a wedge transducer, are investigated. These show an oscillating behavior of the radial profile of the acoustic field amplitude that can be interpreted and modelled as interference phenomenon between forward and backward propagating parts of the Lamb mode, simultaneously generated at the interface between transducer and plate.

Journal Article↗

PubMed2001

Conditions for anomalous acousto-optical diffraction by backward propagating acoustic waves.

Experimental evidence is given of acoustic plate waves, whose group velocity is contradirected with respect to the phase velocity, through a determination of the acoustic wavelength dependence on frequency, in a limited range of frequencies. The dependence dLambda/dOmega>0 between wavelength and frequency is experimentally verified, as the required condition for acousto-optical diffraction, where higher frequency components would scatter light into smaller diffraction angles.

Journal Article↗

PubMed2000

Anomalous propagation characteristics of evanescent waves

An analysis is done of the crossing of a forbidden region in a thin plate by a backward propagating Lamb wave: the refraction/reflection effects undergone by the coupled modes produced at each boundary of the forbidden region are taken into consideration, as well as the penetration of the backward wave as an evanescent wave. The outcome of the acoustic perturbation is analysed for a few angles of incidence and experiments are performed that confirm the theoretical predictions.

Journal Article↗

PubMed1994