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Acoustic signals generated by filamentation of TW laser pulses in water are characterized experimentally and numerically revealing a strong influence of the input pulse duration on the shape of the acoustic signal.
The early diagnosis of liver diseases and/or the identification of any focal lesions are the key issues in considering a favorable prognosis. These objectives require non-invasive dedicated diagnostic tools and justify the development of innovative techniques. The BBMUT project aims to exploit the properties of a new technology of ultrasound probes, called CMUT to propose new techniques for imaging...
Propagation of femtosecond pulses at 800 and 400 nm is studied in water. Acoustic signals generated with MW to TW laser power are characterized, showing a directed and broadband emission in the band 0–20 MHz.
The propagation of intense ultrashort laser pulses in water is affected by group velocity dispersion and nonlinear effects such as self-focusing and multiphoton absorption [1]. For a laser beam with an input peak power exceeding a few MW propagating in water, a filamentation phenomenon can occur producing a self contraction of the beam accompanied by the formation of an extended plasma channel [2]...
Sound reflection by water-saturated sands and glass beads with a flattened surface was studied under controlled laboratory conditions in a wide frequency range, from 200 kHz to 7 MHz. In the ??low-frequency?? domain and in the case of medium sand, the reflected sound level was found to be in good agreement with both classical sonar measurements and classical theories of reflection developed for fluid...
This study deals with the 2-D ultrasonic qualitative and quantitative imaging of child bone. The inverse problem is linearly and non-linearly solved via a Born-based procedure involving minimization of the discrepancies between measurements and modeling data. Inversions of experimental data are presented.
In this paper, we present a low-complexity Low Data Rate (LDR) Ultra Wideband (UWB) demonstration platform suitable for services based on Location and Tracking (LT). This prototyping platform tends to be a testbed on which can be implemented innovative RF, PHY, MAC, networking and location algorithms suitable for low cost, low complexity and low power systems.
This work is concerned with the reconstruction, from measured (synthetic or real) data, of a 2D penetrable fluid-like object of arbitrary cross-section embedded in a fluid of infinite extent and insonified by a plane acoustic wave. Green's theorem is used to provide a domain integral representation of the scattered field. The introduction therein of the Born approximation gives rise to a linearized...
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