Acoustical Materials Association

The Acoustical Materials Associations of New York collects monthly sales data on acoustical materials for its membership. 

The study done by American Acoustical and Insulation Materials Association (1974) showed that these concrete barriers are of very high acoustic reflectivity (95 % and above) and of low sound absorption. This means that concrete barriers are not effective in controlling and reducing traffic noise (Campbell 2000). 

AIMA n. Abbreviation for acoustical and insulating materials association. 

AIMA n Abbreviation for Acoustical and Insulating Materials Association. 

Enhanced chemical reactivity of solid surfaces are associated with these processes. The cavitational erosion generates unpassivated, highly reactive surfaces it causes short-lived high temperatures and pressures at the surface it produces surface defects and deformations it forms fines and increases the surface area of friable solid supports and it ejects material in unknown form into solution. Finally, the local turbulent flow associated with acoustic streaming improves mass transport between the liquid phase and the surface, thus increasing observed reaction rates. In general, all of these effects are likely to be occurring simultaneously. 

Ishikawa, I., Semba, T Tani, Y., and Sato, H. (1990). Development of anisotropic acoustic lenses and applications to material evaluation. Spring Convention Academic Lecture Meeting Reports of 1990 Precision Engineering Association, p. 1111. [56,149, 250, 254]... 

This scattering mode occurs only in piezoelectric materials, i.e., in crystals without inversion symmetry, and is caused by the electric field associated with acoustical phonons. Zinc oxide exhibits very high electro-mechanical coupling coefficients P (see later), exceeding that of quartz [42,59], which is one of the mostly used piezoelectric materials. Zook [60] has calculated the piezoelectrically limited mobility on the basis of the elastic and piezoelectric constants as (see also Rode [54]) ... 

It becomes obvious why surface effects were first observed and studied in the colloidal state. In this case one deals with particles that are so small that the number of atoms or molecules in the surface represents a substantial fraction of all the material that makes up the colloidal system. Colloidal particles are defined as having at least one dimension in the range of 1 micron to 1 nm. In modern chemistry however, particles in the nanometer range are given a special name, nanoparticles. The reason is that in this range several completely unpredictable phenomena start to appear [234], The reason is obvious these particles behave largely quantum-mechanically and therefore completely differently from ordinary colloidal particles. In many instances unusual mechanical, acoustical, electrical and optical properties are associated with nanomaterials, which have also been mentioned in connection with controversial issues such as room-temperature superconductivity and cold fusion. 

Even though these transitions are different in many ways, as demonstrated below, the way in which acoustic energy interacts with polymeric materials permits us to use AW devices to probe changes in polymer film viscoelastic properties associated with these transitions. It should be emphasized up front, however, that evaluating the viscoelastic properties (e.g., modulus values) requires an ability to effectively model the film displacement profiles in the viscoelastic layer. As described in Section 3.1.8, the film displacement effects are dictated by the phase shift, , across the film. Since depends on film thickness, perturbations in acoustic wave properties due to changes in viscoelastic properties (e.g., during polymer transitions) do not typically depend simply on the intrinsic polymer properties. This can lead to erroneous predictions if the film... 

For plane waves propigating in an isotropic homogeneous medium, three acoustic properties are important the speed of sound, the attenuation coefficient (to be discussed), and the characteristic impedance of the media. This impedance z is defined as the ratio of the acoustic pressure to the particle velocity associated with the wave motion in the material. For simple free-field plane waves, tliis is simply the product of the sound speed and density p. 

The stress state, where the stress can be both applied and residual, and the associated strain influence many different material properties, which is especially important in engineering and technological applications. The residual stress and strain can be advantageous or, on the contrary, can provoke a faster failure of machine parts or other manufactured materials. There are different methods to determine the strain and stress in materials mechanical, acoustical, optical and the diffraction of X-ray and neutrons. The diffraction method is applicable for crystalline materials and is based on the measurements of the elastic strain effects on the diffraction lines. There are two kinds of such effects, a peak shift and a peak broadening. The strain modifies the interplanar distances d. In a polycrystalline specimen a peak shift is produced if the average of the interplanar distance modifications on the crystallites in reflection is different from zero. If the dispersion of interplanar distance modifications is different from zero, then a peak broadening occurs. The effect of the strain on the peak breadth is described in Chapter 13. Here we deal only with the peak shift effect caused by the macroscopic, or Type I strain/stress. There is a substantial amount of literature on this subject. The comprehensive... 

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