The sound emission of thin-walled radiating components is a common objective of structural optimisation. Acoustic measures are not implemented in common FE-codes. Thus, different velocitiy based measures will be compared: the kinetic energy, the equivalent radiated power (ERP) and the lumped parameter model (LPM). The most common approach the ERP is based on the sound intensity in normal direct...

The paper considers the active control of harmonic and random sound transmitted through a double-leaf partition using a single distributed actuator and a single distributed sensor. The double-leaf partition consists of a pair of small plates (300x380 mm, separated by a 100 mm air-gap,). An actuator made up of shaped, distributed PVDF offers the possibility of cent rolling the volume velocity of...

Experimental results are presented that demonstrate that ultrasonic attenuation can be used to estimate the biomass concentration of a biological suspension. The attenuation approach avoids the temperature sensitivity of established ultrasound velocity test methods, which have hindered their application in process environments. An empirical model is presented for the estimation of the biomass o...

A Proper Orthogonal Decomposition (POD) is constructed for a Mach 0.9 turbulent jet using a well-validated direct numerical simulation database. Norms are defined based on near-field volume integrals of pressure, turbulence kinetic energy, streamwise velocity, and total enthalpy, two-dimensional integrals of streamswise velocity (to match experimental measurements), and far-field integrals of p...

This paper investigates the sound power radiated from a cracked plate. The sound power is obtained by using a lumped parameters model-based acoustics theory and vibration responses obtained by using the finite element method. It is shown that the vibration mode shapes and crack angle are closely related to the sound radiation characteristics, which can be applied to detect damages such as the c...

Velocity fluctuations in a fluidized suspension of particles are investigated using two new ultrasonic correlation spectroscopies: diffusing acoustic wave spectroscopy and dynamic sound scattering. These techniques probe both the local strain rate and rms velocity of the particles, providing important information about the spatial extent of velocity correlations. Our results demonstrate the pow...

Data collected over more than eight consecutive hours between two source-receiver arrays in a shallow water environment are analyzed through the physics of the waveguide invariant. In particular, the use of vertical arrays on both the source and receiver sides provides source and receiver angles in addition to travel-times associated with a set of eigenray paths in the waveguide. From the trave...

We determine the velocity of sound in the blackbody gas of photons and in the gas of relic photons. Derivation is based on the thermodynamic theory of the photon gas and the Einstein relation between energy and mass. The spectral form for the n-dimensional blackbody is derived. The 1D, 2D and 3D blackbody radiation is specified. It is mentioned the possibility of creation of the Mach cone in ca...