Knowledge of acoustic arrival angle can be useful for studying penetration mechanisms and for estimating sediment sound speed dispersion. The arrival angle of the acoustic field penetrating the water-sediment interface, however, is difficult to measure using sparsely distributed pressure sensors. The arrival angle, as well as amplitude information, can be unambiguously obtained by measuring par...

The application of finite element methods to problems in structural acoustics ( the vibration of an elastic body coupled to an acoustic fluid medium) is considered. New stabilized methods based on the Hellinger-Reissner variational principle with a generalized least-squares modification are developed which yield improvement in accuracy over the standard Galerkin finite element method for both i...

Metamaterials are effectively homogeneous materials that display extraordinary dispersion. Negative index metamaterials, zero index metamaterials and extremely anisotropic metamaterials are just a few examples. Instead of using locally resonating elements that may cause undesirable absorption, there are huge efforts to seek alternative routes to obtain these unusual properties. Here, we demonst...

In this paper, a finite element approach is applied to study the dispersion properties of non-leaky acoustic waves inside boreholes with off-centered LWD (logging while drilling) tools. Both soft and hard formation cases are studied with focus on phase velocity dispersions of Stoneley, dipole and quadrupole modes. When an LWD tool is off-centered, the dispersion curve of the Stoneley mode shift...

We measured the dispersion relation for acoustic longitudinal waves in liquid foams, over a broad frequency range (60-600 kHz). Strong dispersion was found, with two nondispersive behaviors, separated by a negative density regime. A new model, based on the coupled displacements of films, liquid channels, and gas in the foam, rationalizes all the experimental findings.

We show that the coherent interaction between microcavity polaritons and externally stimulated acoustic phonons forms a tunable polariton superlattice with a folded energy dispersion determined by the phonon population and wavelength. Under high phonon concentration, the strong confinement of the optical and excitonic polariton components in the phonon potential creates weakly coupled polariton...

We used the Continuous Wave Scanning Acoustic Microscope to characterize thin film materials. The measurement of the dispersion curve of surface waves and the inversion of this dispersion equation relation, allow to determine the elastic constants, the density or the thickness of a thin layer on a substrate. Besides, it is possible to have qualitative information on the adhesion properties of t...

An experiment has been performed to study the behavior of dust acoustic waves driven at high frequencies f 100 Hz , extending the range of previous work. In this study, two previously unreported phenomena are observed—interference effects between naturally excited dust acoustic waves and driven dust acoustic waves, and the observation of finite dust temperature effects on the dispersion relatio...

We report on a possibility of efficient engineering of the acoustic phonon energy spectrum in multishell tubular structures produced by a novel high-tech method of self-organization of microand nano-architectures. The strain-driven roll-up procedure paved the way for novel classes of metamaterials such as single semiconductor radial microand nano-crystals and multi-layer spiral microand nano-su...

Body weight, length, and vocal tract length were measured for 23 rhesus macaques (Macaca mulatta) of various sizes using radiographs and computer graphic techniques. linear predictive coding analysis of tape-recorded threat vocalizations were used to determine vocal tract resonance frequencies ("formants") for the same animals. A new acoustic variable is proposed, "formant dispersion," which sh...