Search PubMed⌕ Search

Biomedical subjects

G Shkerdin

Publications and source records attributed to G Shkerdin.

4 recordsLinked to original sources
PubMed2003

Influence of planar cracks in plates on reflected and transmitted fields of Gaussian acoustic beams.

The scattering of a Gaussian beam by a rectangular crack is studied by means of the radiation mode model. The orthogonal set of modes for a L/S/V structure is derived, and a general mode decomposition formula is developed. The influence of a crack on the reflected and transmitted fields of a bounded beam, incident at critical angles of the L/S/L- and the L/S/V structure, is studied and physical interpretations are given. From those interpretations, the starting point of the crack is deduced along with the length and distance to the surface. Effects on focused beams are considered as well.

Acoustics↗
PubMed2000

Extension of the mode method for viscoelastic media and focused ultrasonic beams.

In the present study viscoelasticity is introduced in the mode model and the orthogonality condition is adapted for viscous media. The expansion of convergent acoustic Gaussian beams in terms of radiation modes for viscoelastic media is studied as well. The effects on the reflected and transmitted profiles of acoustic beams incident from an ideal liquid onto a viscoelastic plate are shown and physically explained. It is shown that focusing the incident beam can suppress divergence effects and gives the possibility to measure shear wave attenuation coefficients.

Acoustics↗
PubMed2000

Bounded beam interaction with thin inclusions. Characterization by phase differences at Rayleigh angle incidence.

A theoretical study of the reflection of a bounded Gaussian ultrasonic beam, incident onto a rectangular inclusion located near a fluid/solid half-space interface, is presented. The thickness of the inclusion is assumed to be much smaller than the ultrasonic wavelength in the solid. It is shown that, at critical Rayleigh angle incidence, the phase in the point of maximum amplitude of the shifted reflected lobe is very sensitive to dimension variations of the inclusion, and thus useful for inclusion characterization. The modelization of the problem is based on mode theory.

Acoustics↗