Acoustic interferometer

About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.

The effect of a surface impedance load on the behavior of quasi-Rayleigh waves near a cylindrical cavity

Abstract: The effect of a surface impedance load on the properties of axisymmetric quasi-Rayleigh waves propagating along the boundaries of a cylindrical cavity is investigated. By solving the problem by means of the impedance method, a dispersion equation for these waves is obtained. It is shown that the equation can be represented as the condition that the determinant of the sum of impedance matrices of the load and the medium is zero. Analysis of this equation allows one to investigate the effect of the surface load on the behavior of quasi-Rayleigh waves and on their critical frequencies. The conditions that should be met by the impedance load for quasi-Rayleigh waves to be absent near the cavity or for one or two such waves to exist are determined. The choice of the load is specified for the propagating quasi-Rayleigh wave to possess preset dispersion properties. The conclusions drawn on the basis of this study are illustrated by several examples of load models that can be implemented in practice.

Diffraction of Acoustic and Electromagnetic Waves by Impedance Cones

Abstract: This paper deals with a canonical problem in the theory of diffraction, namely, diffraction of acoustic and electromagnetic waves by impedance cones. The method can be applied in general for acoustic potential or Debye potentials in electromagnetics satisfying the Helmnoltz equation. This paper will be centred on a more demanding case, i.e., diffraction of an electromagnetic plane wave by an axially anisotropic impedance cone. The diffraction coefficients of such an impedance cone in the so-called oasis, that is, domain where only a spherical wave beside the incident plane wave exists, will be determined in an analytical-numerical way.

Amplitude multiplexing of Mach-Zehnder interferometer array and its application to locating acoustic emission

Abstract: We report an amplitude division multiplexed interferometric sensor array for locating acoustic emission. The interferometer is composed of 3 arms, the two sensing arms have different interference amplitude with the reference arm, so we can judge whether a sensor receives sound or not from the composite interference amplitude. For single sound source, the sound-receiving delay of two sensors can be obtained from the time when the interference amplitude changes, and the sound source location relative to the sensors can also be achieved in a 1-D system. Preliminary experiments were carried out and demonstrated a one-dimensional (1-D) location accuracy of better than 1cm. The system can be extended for 2-D and 3-D location of acoustic emissions by adding one or two more sensing arms, respectively, in the interferometer.