The problem of the propagation of sound waves radiated by a source in a fluid moving with subsonic velocity between two parallel walls or inside a cylindrical tube is considered in [2]. The most interesting thing of this problem is that waves may occur with constant amplitude coming from infinity. This article gives the calculation of the energy transport in the wave guides. It is shown that it...

Condensation of atoms from the vapor into a third sound resonance is expected to be capable of acoustic amplification. This results from normal to superfluid conversion that coherently accommodates atoms into the third sound velocity field. Consideration of third sound in light of the equilibrium detailed balance between vapor particles and the superfluid film provides further evidence that aco...

Experimental techniques employed in the present work for the measurement of density, ultrasonic velocity, viscosity and working principle of ultrasonic interferometer have been discussed in this paper. In addition to that, the present paper also includes a brief discussion on experimental setup, different parts, procedure of ultrasonic interferometer, and various thermodynamic parameters which ...

This article focuses on the hydration, and associated microstructure development, of b-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration kinetic and volumetric models for gypsum is addressed. The presented models predict the sound vel...

Techniques for the use of audio-frequency sound waves in the measurement of flow rate and particle size and the estimation of the volume of material contained in partially closed vessels are described and discussed. INTRODUCTION Non-invasive interrogation of systems and processes involving dry particulate materials is particularly challenging. X-rays and γ-rays, for example, offer the prospect ...

BACKGROUND Male parasitic wasps attract females with a courtship song produced by rapid wing fanning. Songs have been described for several parasitic wasp species; however, beyond association with wing fanning, the mechanism of sound generation has not been examined. We characterized the male courtship song of Cotesia congregata (Hymenoptera: Braconidae) and investigated the biomechanics of sou...

In this article the sound velocity through a mix is correlated to the hydration degree of the mix. Models are presented predicting the sound velocity through fresh slurries and hardened products. These two states correspond to the starting and finishing point of the hydration process. The present research shows that a linear relation between the amount of hydration-product (gypsum) formed (Smit...