The effect of a combined system of the bed suction and jet injection as a pier-scour countermeasure on the turbulent flow field is studied in a laboratory flume using an Acoustic Doppler Velocimeter (ADV). The three components of the velocities in the vertical symmetry plane in the equilibrium scour hole in front and rear of the pier under 3-jet injections and bed suction rate Qs/Q0 = 2%located...

The objectives are i) to characterize the ambient noise field coherence for the data recorded on the North Pacific Acoustic Laboratory (NPAL) and ii) to apply broadband, full field processing to characterize the sources in the local environment. Coherence measurements based upon field data are fundamental to understanding how the various sources of the ambient noise superimpose and lead to both...

Accuracy and speed of algorithms play an important role in the reconstruction of temperature field measurements by acoustic tomography. Existing algorithms are based on static models which only consider the measurement information. A dynamic model of three-dimensional temperature reconstruction by acoustic tomography is established in this paper. A dynamic algorithm is proposed considering both...

The prediction of the acoustic field evolution on a day to week frame, in a given oceanic area, is an important issue in sonar performance modeling. It relies primarily on acoustic propagation models, which convert water column and geometric/geoacoustic parameters to ‘instantaneous’ acoustic field estimates. In practice, to model the acoustic field, even the most accurate acoustic models have t...

(Near-field Acoustic Holography, Audio Production, Guitar) In recording studios, the placement of microphones to record an acoustic guitar is very much subjected to trial and error and audio engineer preference. In order to make more informed microphone placement decisions, Near-field Acoustic Holography is used to study the sound pressures of the guitar. This technique involves solving the int...

A new approach for characterizing high intensity focused ultrasound (HIFU) transducers is presented. The technique is based upon the acoustic streaming field generated by absorption of the HIFU beam in a liquid medium. The streaming field is quantified using digital particle image velocimetry, and a numerical algorithm is employed to compute the acoustic intensity field giving rise to the obser...

A tool for calculating the beamformer setup associated with a specified pulsed acoustic field is presented. The method is named Pulsed Plane Wave Decomposition (PPWD) and is based on the decomposition of a pulsed acoustic field into a set of PPWs at a given depth. Each PPW can be propagated to the location of the elements of an array transducer by a time delay. The contribution of each propagat...