Victor J. Sánchez-Morcillo

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A dynamical system of equations describing parametric sound generation (PSG) in a dispersive large aspect ratio resonator is derived. The model generalizes previously proposed descriptions of PSG by including diffraction effects and is analogous to the model used in theoretical studies of optical parametric oscillation. A linear stability analysis of the(More)
The propagation of nonlinear compressional waves in a one-dimensional granular chain driven at one end by a harmonic excitation is studied. The chain is described by a Fermi-Pasta-Ulam (FPU) lattice model with quadratic nonlinearity (α-FPU model), valid for strong initial compression of the chain by an external static force. A successive approximations(More)
The Ising-Bloch transition for domain walls in spatially extended nonlinear systems is a known phenomenon. We show a similar transition for extended patterns, such as labyrinths and stripes. The analysis is performed in the frame of the parametrically driven Ginzburg-Landau equation, which is a paradigmatic model for a variety on nonlinear systems showing(More)
We show that nonmonotonic (oscillatory) decay of the boundaries of phase domains is crucial for the stability of localized structures in systems described by Swift-Hohenberg equation. The less damped (more oscillatory) are the boundaries, the larger are the existence ranges of the localized structures. For very weakly damped spatial oscillations,(More)
A sound diffuser is proposed based on sonic crystals, structures formed by a periodic distribution of cylindrical scatterers in a host medium, which is usually air. The diffuser is a so-called biperiodic structure, as formed by two arrays of sonic crystals with slightly different periodicities. Large diffusivity at low frequencies is achieved when the(More)
A comprehensive experimental, analytical and numerical study of the true focal region drift relative to the geometrical focus (focal shift effect) in acoustic focused beams and its nonlinear evolution is presented. For this aim, the concept of Fresnel number, proportional to the linear gain, is introduced as a convenient parameter for characterizing focused(More)
1 College of Mechanics and Materials, Hohai University, Nanjing 210098, China; (Y.Z.); (L.-H.J.) 2 College of Civil Engineering, Tongji University, Shanghai 200092, China; 3 College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China; *(More)
The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in frequency by modifying the orientation of the square-rod(More)
Shape transformations in driven and damped molecular chains are considered. Closed chains of weakly coupled molecular subunits under the action of spatially homogeneous time-periodic external field are studied. The coupling between the internal excitations and the bending degrees of freedom of the chain modifies the local bending rigidity of the chain. In(More)
The formation of high-order Bessel beams by a passive acoustic device consisting of an Archimedes' spiral diffraction grating is theoretically, numerically, and experimentally reported in this paper. These beams are propagation-invariant solutions of the Helmholtz equation and are characterized by an azimuthal variation of the phase along its annular(More)