Jean-Christophe Valière

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It is shown that the standard beamformer technique is inadequate for both the source location and the measurement of a simple dipole and that this is due to the assumption of monopole propagation in the calculation of the phase weights used to steer the focus of the array. A numerical simulation is used to illustrate the problem and to develop a correction(More)
This paper considers the problem of estimating acoustic particle velocity and convection velocity in the air by means of Laser Doppler Velocity (LDV) measurement. Closed-form for the Cramér-Rao Bounds (CRB) on the estimates of the velocity parameters, for a sine wave excitation, are derived and simplified expressions are given. Moreover, a Maximum(More)
Measurements of the axial streaming velocity are performed by means of laser doppler velocimetry in an experimental apparatus consisting of a waveguide having loudspeakers at each end for high intensity sound levels. Streaming is characterized by an appropriate Reynolds number Re(NL), the case Re(NL)<<1 corresponding to the so-called slow streaming and the(More)
Measurements of streaming velocity are performed by means of Laser Doppler Velocimetry and Particle Image Velociimetry in an experimental apparatus consisting of a cylindrical waveguide having one loudspeaker at each end for high intensity sound levels. The case of high nonlinear Reynolds number ReNL is particularly investigated. The variation of axial(More)
A laser Doppler velocimetry bench adapted for measuring acoustic particle velocities is used to measure sinusoidal structural velocities in order to assess the performance of two signal processing techniques, one available commercially and the other being developed in our laboratory. Considering a sinusoidal excitation signal of the vibrating structure,(More)