Results 321 to 330 of about 1,550,252 (358)

Experiments on Acoustic Absorption in Sand and Soil

The Journal of the Acoustical Society of America, 1950
The acoustic absorption of sand and soil with varying amounts of water (dry to saturated) has been investigated the 10- to 100-kc range. Two methods were used. In one, the source and a number of equally spaced probe microphones were imbedded in the medium.
I. Rudnick, W. L. Nyborg, H. K. Schilling   +2 more
openaire   +2 more sources

Absorption of acoustic energy by plant leaves

The Journal of the Acoustical Society of America, 1981
We investigated the vibration of leaves of four plant species in a sound field using a laser-Doppler-vibrometer system. All leaves behave as linear mechanical systems when driven by sound and noise at sound pressure levels (SPL) of up to 100 dB re 20 μPa.
Axel Michelsen, Maurice J. M. Martens
openaire   +2 more sources

Mossbauer absorption by globules in an acoustic field

Journal of Physics D: Applied Physics, 1994
The acoustic modulation of the resonance gamma absorption by spherical particles containing a Mossbauer label is studied. To find the Van Hove function the expression for the acoustic displacements of the atom is used, which is obtained in the framework of the elasticity theory, assuming that the particle size is small relative to the sound wavelength.
A.V. Zatovsky, Andrei Zvelindovsky
openaire   +2 more sources

Acoustical absorption in the atmosphere at high altitudes.

The Journal of the Acoustical Society of America, 2008
Before 1978, acoustical absorption in the atmosphere was modeled semiempirically based on numerous experimental studies, especially those of Harris and Tempest. In 1969, this author presented a semiempirical model to explain the divergence of the absorption data from theoretical values predicted from classical absorption and molecular relaxation of ...
openaire   +2 more sources

Measurement of energy flow and acoustic absorption

The Journal of the Acoustical Society of America, 1984
The measurement of energy flow in rooms may be conveniently carried out using a real time intensity analyzer allowing one to plot the flow in the planes of interest. Supplemented with absorption measurements carried out with the same setup, a thorough knowledge of the important parameters, such as local absorption, controlling the acoustics of a room ...
openaire   +2 more sources

Observation of Coherent Perfect Acoustic Absorption at an Exceptional Point.

Physical Review Letters
Non-Hermitian systems have recently shown new possibilities to manipulate wave scattering by exploiting loss, yet coherent perfect absorption at an exceptional point (CPA EP) remains elusive in acoustics.
Yifei Xia, Zi-Xiang Xu, Yu-Ting Yan, A. Chen, Jing Yang, Bin Liang, Jianchun Cheng, Johan Christensen   +7 more
semanticscholar   +1 more source

Acoustical absorption in Bragg diffraction imaging

Journal of Physics D: Applied Physics, 1977
The influence of absorption of the ultrasound in the water of the Bragg cell of Bragg diffraction imaging systems is studied theoretically. It is shown that the optical image formed is that of a distorted sound field which can be written in terms of the unattenuated acoustical spectrum and geometrical factors. The absorption causes a loss of resolution
openaire   +2 more sources

Nuclear acoustic resonance absorption and dispersion

Physics Letters A, 1977
Abstract A generalized form of the “Kubo susceptibility” is presented correlating NAR absorption and NAR dispersion with the sound induced perturbation Hamiltonian h ( t ).To illustrate the advantage of NAR susceptibility, we give the first quantum theoretical treatment of dipole NAR in metals whose results are in agreement with experiment.
openaire   +2 more sources

Absorption Characteristics of Nonlinear Acoustic Resonators

The Journal of the Acoustical Society of America, 1968
In the present note, which is a supplement to a previous paper [U. Ingard and H. Ising, J. Acoust. Soc. Amer. 42, 6–17 (1967)] on the nonlinear impedance of an orifice, the absorption characteristics of a nonlinear resonator absorber have been computed as a function of frequency for different values of design parameters and incident sound-pressure ...
openaire   +2 more sources

Electromagnetically induced acoustic transparency and absorption

Journal of Experimental and Theoretical Physics Letters, 2002
The possibility of controlling the passage (from transmission to absorption) of a hypersound through a low-temperature paramagnet using the resonance electromagnetic pumping of lower frequency is substantiated. The effect has a quantum nature and is analogous to (though somewhat different from) the optical phenomenon of electromagnetically induced ...
openaire   +2 more sources