Volume 103, Issue 2, February 1998
Index of content:
- ULTRASONICS, QUANTUM ACOUSTICS, AND PHYSICAL EFFECTS OF SOUND 
103(1998); http://dx.doi.org/10.1121/1.421244View Description Hide Description
This paper considers sound propagation in suspensions of rigid particles, when both heat and momentum are exchanged between the particles and the host fluid. A theory is developed for small-amplitude, single-frequency oscillatory motions, on the assumption that the temperature of each particle is uniform. This theory applies to dilute suspensions that have arbitrary particle and fluid material densities, and yields the attenuation and the speed of sound in the suspension in terms of the particles’ velocity and temperature fluctuations. These quantities are not specified by the theory, but are available for some situations of interest which cover a very wide frequency range. In the particular case when the particle force and the heat transfer rate are not affected by the compressibility of the fluid, the particle’s velocity and temperature are given by closed-form results that are used to obtain explicit formulas for the attenuation and sound speed. For this case, the present theory reproduces all fundamental predictions available in the literature, and yields new basic results where none seem to exist. Results are also shown for the important case when the particle force includes compressibility effects in the fluid. These provide a unified description for the attenuation and the dispersions which covers the viscous and the scattering regions, as well as the transition region between them.
Nonlinear inversion of the wave equation in a half-space for density and shear modulus determination103(1998); http://dx.doi.org/10.1121/1.421245View Description Hide Description
This paper deals with the problem of multi-parameter nonlinear inversion of the wave equation in an elastic half-space. A numerical approach combining Born iteration and a regularizing technique is presented for simultaneously reconstructing 2-D distributions of density and shear modulus in a scatterer embedded in a half-space. The well-to-well source–receiver scheme commonly used in geophysical exploration is considered in the model in which two incident frequencies are used to uncouple the parameters in frequency domain. The weighted residual method, along with bilinear interpolating functions, are used in the discretization procedure. Computer simulations have been conducted on several examples with different density and shear modulus configurations. The numerical results show that the approach proposed has a uniformly convergence for the given objects and has a feature of treating the limited-source well-to-well scheme that causes a more ill-conditioned equation in the inversion procedure.
Evolution of phonon noise and phonon state preparation in a model for generation of hypersonic phonons by laser103(1998); http://dx.doi.org/10.1121/1.421203View Description Hide Description
The evolution of phononnoise and the quantum correlation between phonon and photon in a model of the generation of hypersonic phonons by laser have been analyzed according to the quantum theory. The cases of perfect phase matching, phase mismatch, and losses have been discussed, respectively. It is shown that the phonon state preparation can be performed by measuring a quadrature component of the idle light field under certain conditions.