Fig. 6: Z-derivative of the absorbed intensity and its profile reconstruction.
From: Sierpiński carpet-inspired hierarchical patterning of porous materials for sound absorption
a Spatial derivative in the z-direction of the acoustic field intensity (\(\frac{\partial I}{\partial z}\)) along a radial line connecting the center of the cylinder to its right edge. b Reconstruction of the \(\frac{\partial I}{\partial z}\) profiles denoting the areas of fastest intensity decay (close to the air holes). Intensity derivative distributions have been extracted in correspondence of the star-like markers reported in Fig. 3.
