Acoustic absorption factor

This definition is special to acoustics and is different from the usage in radiation, where the absorption factor corresponds to the acoustic dissipation factor. 

The absorption coefficient at a boundary, also called the absorption factor or sound power absorption coefficient, is defined as the fraction of the incident acoustic power arriving at the boundary that is not reflected, and is therefore regarded as being absorbed by the boundary (Morfey, 2001) ... 

The strongest contribution to the projected mean square displacement (ku)) and therefore to the absorption probability S(E) originates from C-Fe-C and N-Fe-C bending modes (8Ai, 22E, 23E, and 24E in Table 9.2). However, the energy range of these modes (8-15 meV) strongly overlaps with that of the acoustic modes (with composition factor = 0.17, = 337, wtpe = 57) and therefore... 

From the individual contributions of the modes to the msd along the c-axis ( 6 pm ) and along the a-axis ( 8 pm ), the corresponding calculated molecular Lamb-Mossbauer factors for the c-cut crystal (/Lm,c = 0.90) and for the a-cut crystal = 0.87) were derived. Comparison with the experimental /-factor, i.e., / P = 0.20(1) and/ N> = 0.12(1) [45], indicates that by far the largest part of the iron msd must be due to intermolecular vibrations (acoustic modes) of the nitroprusside anions and its counter ions. This behavior is reflected in the NIS spectrum of GNP by the considerable onset of absorption probability density below 30 meV in Fig. 9.36a. 

Acoustic measurements can also be used as a structural probe, since the acoustic properties, especially sound absorption, are related to many structural factors, such as transition temperatures, morphology, cross-link density, etc. Finally, they can be used as a source of engineering data, especially in the building and construction field for the absorption of unwanted sound, the construction of acoustically transparent windows, underwater acoustics, etc. 

Abbe refractometer, 298 Abrasion, 841 loss factor, 831 resistance, 831, 881 Absorption, 313 coefficient, 288 index, 313 Absorptivity, 288 Acceleration of nucleation, 735 Acoustic... 

Acoustic levitation has also been used for microtitration with absorptive and fluorescent indicators. The addition of titrant was efficiently controlled via a piezoelectric micropump. This application testifies to the possibility of using this technique in routine laboratories where sample and (or) reagent availability may be a limiting factor [90]. 

The primitive cells of the n H and 3n R SiC poly types contain n formula (Si-C) units, and the unit cell of the polytypes along the c-axis is n times larger than that of the basic 3 C SiC polytype. The BZ of the corresponding polytype is thus reduced in the T — L direction by a factor f/n [70]. One then speaks of folded BZ and some of the folded acoustical phonons with non-zero frequencies at the zone centre are IR- and Raman-active. Their absorptions, with lines as sharp as 0.03 cm-1 at LHeT have been reported for the 6H and 15R SiC polytypes ([77], and references therein). 

The kinetic ener produced by the absorption of a modulated beam of light in a resonator causes the excitation of acoustic normal modes in the cavity. The rimple theoretical approach considered in this section is that of a lossless gas in a rigid container with perfectly insulating walls. This simple model yields reasonable values for the eigenfrequencies of the resonator. However, for an accurate description of experimentally determined resonance frequencies and the corresponding Q factors, dissipation effects, deviations of the cavity from the ideal geometry, etc. must be taken into account. The advances made in recent years in an understanding of these loss mechanisms will be discussed in the next section. 

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