| Popis: |
This paper is devoted to the study of water‐saturated porous plate/water layered structures by means of the transition terms defined from the reflection and transmission coefficients R and T as follows: TTsym=(1‐(R+T))/(2i) , TTasym=(1‐(R‐T))/(2i). They are the eigenvalues of the scattering matrix of the water‐immersed structure and are directly connected with its symmetric or antisymmetric vibrations. The N porous plates associated in our structures obey Biot's theory which is first used to calculate the reflection and transmission coefficients of a unique water‐saturated plate. An induction on N process allows to find the reflection and transmission coefficients of a given N plate/water‐layer structure. The plates used in the experiments at normal incidence are 5mm thick. The reflection and transmission coefficients of sets of 1, 2, 3, and 4 water immersed plates, separated from each other by a 1cm water gap, are measured thanks to two wideband transducers with central frequency 0.5MHz. There are good a... |
