Fluidized beds are used in a variety of process industries because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Minimum fluidization velocity is an important factor in understanding the hydrodynamic behavior of fluidized beds, and this characteristic may be modified through high frequency (sound) vibrations. The effects caused by sound wave frequ...

We present results from large-scale numerical simulations of a first order thermal phase transition in the early Universe, in order to explore the shape of the acoustic gravitational wave and the velocity power spectra. We compare the results with the predictions of the recently proposed sound shell model. For the gravitational wave power spectrum, we find that the predicted k−3 behavior, where...

The regular behavior of sound sources helps us to make sense of the auditory environment. Regular patterns may, for instance, convey information on the identity of a sound source (such as the acoustic signature of a train moving on the rails). Yet typically, this signature overlaps in time with signals emitted from other sound sources. It is generally assumed that auditory regularity extraction...

| Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales. The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables pr...

Headphones and earphones have many extremely small holes or narrow slits; they use sound-absorbing or porous material (i.e., dampers) to suppress vibratory system resonance. The air viscosity in these acoustic paths greatly affects the acoustic properties. Simulation analyses such as the finite element method (FEM) therefore require knowledge of the material properties of sound-absorbing or por...

In this paper a numerical model to study the vibro-acoustic behavior of a laminated plate backed by a poroelastic foam layer is developed. Such approach consists on a coupled mitigation strategy aiming either mechanical vibration suppression or acoustic attenuation as well. The laminated plate model consists of fiber laminae with interleaved viscoelastic layers in standard constrained or integr...

The high frequency dynamics of Indomethacin and Celecoxib glasses has been investigated by inelastic x-ray scattering, accessing a momentum-energy region still unexplored in amorphous pharmaceuticals. We find evidence of phonon-like acoustic dynamics, and determine the THz behavior of sound velocity and acoustic attenuation. Connections with ordinary sound propagation are discussed, along with ...

The current primary method for hydrophone calibration is the three-transducer spherical-wave reciprocity at NPL, covering the frequency range between 1 kHz up to 500 kHz with expanded uncertainties as low as ± 0.5 dB. Optical methods can provide an alternative method for primary calibration as they directly measure the acoustic particle velocity at a specific point in the field. The hydrophone ...

The quality of the communication between teachers and students and ultimately, of classroom education itself, is closely linked to the acoustic quality of the auditorium. This acoustic quality can be characterized based on the reverberation time (RT), speech transmission index (STI) and the sound insulation. In this context, an acoustic study was conducted in an auditorium located in the Higher...

Porous metallic material has become a kind of typical multifunctional material with the quick development of advanced manufacturing and forming process technologies in past years. At present, it has also been a structural function material with the characteristics of ultra-light weight, high specific strength and rigidity. As a sound absorbing material in noise control engineering, the acoustic...