Absorption acoustic

Shear velocity and acoustic absorption have been studied as a function of OH content and fictive temperature for four different vitreous siUca samples (170). AH showed a shear—velocity minimum at 80—100 K. The magnitudes of the minima are influenced by OH content and fictive temperature. The samples having the highest OH content and lowest fictive temperature display the lowest losses. 

Medium-density mat with flexible facings of paper or scrim stitched through. Quilts are used for acoustic absorption behind perforated or slatted panels and ceilings. 

In the case of sound, the absorption coefficient (which is also called the acoustical absorptivity) is defined as the fraction of the incident sound energy absorbed by a surface or medium. the surface being considered par of an infinite area. 

Holmes, A.K, Challis, R.E. 1996. Acoustic absorption due to proton transfer in solutions of proteins, peptides and amino acids at neutral pH. J. Acoustic Soc. Am. 100, 1865-1877. 

A review of the common methods of measuring acoustic absorption and dispersion is presented by Cottrell and McCoubrey [9], The ultrasonic interferometer, the absorption tube, the condenser transducer, and the reverberation chamber are the standard types of apparatus. 

DC1, HF, and DF, rotational collision numbers appear to decrease with increasing temperature over the intervals for which data are available (see Table 3.2). His comparison of acoustic-absorption and thermal-conductivity data for both HC1 and H20 indicates consistent results for these two experimental methods and their respective interpretations. However, the apparent decrease of Zr with increasing temperature is in contradiction to Zeleznik s... 

Eigen, M. and Tamm, K. Schallabsorption in Elektrolytloesungen als Folge chemischer Relaxation I (Acoustic absorption in electrolyte solutions as a consequence of chemical relaxation I.) Z Elektrochem. 1962, 66, 93-121. 

Based on in atm units. AA = Acoustic absorption PVT = Pressure, Volume, Temperature ... 

J. E. Piercy and J. Lamb. Trans. Faraday Soc. 52, 930-40 (1956). Acoustic absorption experiment and theory, acetic acid solutions, 1-106 me. 

The temperature increase inside an embedded thermocouple due to acoustic absorption has been studied in detail by Fry [32]. The initial temperature rise (AT,) (Figure 7) is the same for an embedded thermistor as for a thermistor coated with a very thin layer but the latter rapidly reaches an equilibrium temperature due to heat losses (resulting from heat conduction and acoustic streaming) as can be... 

As already mentioned thermal probes of several different types have been used for acoustic power measurements. In 1954 Fry published a very detailed study on the determination of absolute sound levels and acoustic absorption coefficients [32], The probe which was used is shown in Figure 9 and is made of a thermocouple junction (copper constantan or iron constantan 0.0005 inch diameter) imbedded in a thin disk of absorbing liquid. The absorbing liquid is separated from the medium... 

The calculation of sound intensity requires a knowledge of the acoustic absorption coefficient of the imbedding material and its heat capacity per unit volume at the temperature at which measurements are made, according to,... 

Stationary relaxation methods include sound absorption und dlNpcrRlon and dielectric dispersion. A sound wave is used to perturb thc system (hat causes temperature and pressure alterations on an oscillating electric field. Then, chemical relaxation is measured by determining adsorbed energy (acoustical absorption or dielectric loss), or a phase lag that is dependent on the frequency of a forcing function (Bernasconi, 1986 Sparks, 1989). In this chapter, only transient relaxation methods will be discussed. 

Models are often developed to explain certain kinds of data, ignoring other kinds that also might be pertinent. The initial development of Pitzer s equations (33.34) for activity coefficients in concentrated solutions was focused on explaining measurements of vapor pressure equilibrium and of electromotive force (emf). The data could be explained by assuming that the electrolytes examined were, at least in a formal sense, fully dissociated. Later work using these equations to explain solubility data required the formal adoption of a few ion pair species (30). Even so, no speciation/activity coefficient model based on Pitzer s equations is presently consistent with the picture of much more extensive ion-pairing based on other sources, such as Smith and Martell s (35) compilation of association constants. This compilation is a collective attempt to explain other kinds of data, such as electrical conductance, spectrophotometry, and acoustic absorption. 

Acoustic absorption in open-cell foams is very useful in quieting reflected noise. High thermal and high electrical insulation are due to the very low conductivity of the ubiquitous gas phase, and are definitely best at lowest density even choice of the... 

Textile membranes are thin, low-mass structures. This means that they provide little acoustic insulation, although micro-perforated foils in combination with other membranes may provide substantial acoustic absorption (Pudenz, 2004, p. 60). The tensioning of the membrane surface means that at times of heavy rain or hail, although these are usually of short duration, skin drumming occurs. This phenomenon is even more pronounced with inflated ETFE cushions. 

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