V.T.Grinchenko, V.V.Krizhanovskii, V.V.Krizhanovskii (jr.) Model estimates of the potential efficiency for coaxial inhomogeneity detection inside the wall of a finite pipe |
Acoustic bulletin, Vol. 7 ¹ 2, (2004) |
| The detection efficiency for coaxial inhomogeneous layer inside the wall of the finite cylindrical pipe after the acoustic field excited by the incoherent axisymmetric source on pipe's internal surface and registered by piezosensors on its external lateral wall is estimated. The informative parameters of inhomogeneity are the layer thickness and the density, as well as propagation speed for acoustic oscillations and their attenuation. The structure of the vibrational velocity field registered on the external lateral wall of layered pipe is given. The statistical problem on detection of the signal from the layer-inhomogeneity against a background of uncorrelated interference is formulated. The cross-spectral power density of the acoustic field in the set of spaced reception points on the pipe surface was used as the informative statistical characteristics. The detection efficiency was estimated after the Neumann-Pearson criterion. The dependencies of the non-uniform layer detection efficiency on its thickness and acoustic parameters are presented. The influence of the source spatial extent, the number of the reception points, their arrangement and signal frequency band on the efficiency of the non-uniform layer detection is considered. The investigated model situation reflects some typical features of the acoustic signal formation and propagation in the respiratory tract of a patient with pathological changes of the lung tissue. |
|
KEY WORDS: coaxial inhomogeneous layer, piezosensor, acoustic velocity and decay in layer, the Neumann—Pearson criterion, pathological changes of the lung tissue |
| TEXT LANGUAGE: Russian |