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Diffraction of sound pulses on a spherical target in an oceanic waveguide covered with ice

Grigorieva N., Kupriyanov M., Ostrovskiy D., Stepanova D.

Hydroacoustics

2016

Vol. 19

139--144

This paper is devoted to modeling of the pulse scattering by a spherical target immersed in a homogeneous waveguide covered with ice. For calculating the echo signal in the frequency domain we have followed Hackman and Sammelmann’s general approach. The arising scattering coefficients of a sphere were evaluated with the use of the normal mode method. The amount of normal modes forming the backscattered field is determined by the given directivity of the source. The emitted signal is a pulse with a Gaussian envelope. Computational results are obtained in a wide frequency range 8 - 12 kHz for water depths equal to several hundreds of m, and distances between the source/receiver and a target from 1 km up to 10 km. The target is assumed to be acoustically rigid or fluid. In particular, the properties of the ice cover and a scatterer may coincide.

The Structire and Certain Properties of the Pzt-Type Thin Film Transducers

Surowiak Z., Kupriyanov M., Czekaj D., Gomes M., Kofanova N., Kuprina Y., Tshebanova E.

Molecular and Quantum Acoustics

2002

Vol. 23

405-412

By means of X-ray diffraction analysis and Raman spectroscopy the process of crystallisation of PZT-type thin films was studied. RF-magnetron sputtering of the multicomponent ceramic targert ((Pb0.97Ba0.01Ca0.01Sr0.005)(Zr0.52Ti0.46)O3 + 1.4wt.%Bi2O3 + 0.3wt.%GeO) employed to the thin film fabrication. Policrystaline thin films deffering in thickness, content of rhombohedral and tetragonal phases, elementary cell parameters, as well as relative content of pyrochlore and perovskite phases have been obtained. Results of investigation into the pyrochlore-perovskite reconstructive phase transitions (RPT) are discussed. On the basis of the experimental measurements as well as the crystal-chemical analysis of mutal realtions between fluorite-type structure, pyrochlore-type structire, C-phase of rare earths, and perovskite-type structure, an atempt to determine possible mechanism of the observed PRT have been indertaken.