Attenuation ultrasound

In this paper we propose a multivariable regression approach for estimating ultrasound attenuation in composite materials by means of pulse-echo measurements, thus overcoming the problems with limited access that is the main drawback of through-transmission testing. 

Romdhane M, Gadri A, Contamine F, Gourdon C, Casamatta G (1997) Experimental study of the ultrasound attenuation in chemical reactors. Ultrason Sonochem 4 235-243... 

Sympatec (www.sympatec.com) Ultrasound attenuation Particle sizing Yes Yes... 

Part II of the book deals with lesser known aspects of US for the analytical chemists such as its use as an energy source for detection purposes. Thus, ultrasound-based detection techniques viz. US spectrometry in its various modes including ultrasound attenuation, ultrasonic velocity, resonant ultrasound, laser-generated, ultrasound reflection and acoustic wave impedance spectroscopies) are dealt with in Chapter 9. Finally, Chapter 10 is devoted to seleoted applioations of US spectrometry — mostly non-analytical applications from whioh, however, analytical chemists can derive new, interesting analytical uses for ultrasound-based deteotion techniques. 

Applications of ultrasonic techniques to solid-gas systems rely on the fact that velocity and attenuation of US-waves in porous materials is closely related to pore size, porosity, tortuosity, permeability and flux resistivity. Thus, the flux resistivity of acoustic absorbents oan be related to US attenuation [118,119], while the velocity of slow longitudinal US is related to pore tortuosity and diffusion, and transport properties, of other porous materials [120]. Ultrasound attenuation is very sensitive to the presence of an external agent suoh as moisture in the pore space [121] and has been used to monitor wetting and drying prooesses [122] on the other hand, US velocity has been used to measure the elastic coefficients of different types of paper and correlate them with properties such as tensile breaking strength, compressive strength, etc. [123]. 

Sensors for particle size characterization used for crystallization include ultrasound attenuation measurement/ " laser diffraction/ and laser backscatteiing/ commercially called focused beam reflectance measurement (FBRM). Ultrasonic attenuation spectroscopy has been used to monitor the crystallization process parameters such as the crystal size distribution, concentration, and the onset of nucleation during batch crystallization of L-glutamic acid/ Off-line laser diffraction has been used to measure the crystal size distribution in the development of the crystallization process for a pharmaceutical intermediate/ ... 

In addition,there are several experimental options available for particle size measurement alone. They include single particle optical sensing (SPOS), laser diffraction (LD), and ultrasound attenuation (UA). 

As we see from these formulae the elasticity constant Cee (the reciprocal of elastic susceptibility) tends to zero at T = Tc. The experimental dependence of the modulus of elasticity upon temperature is measured at T > Tc only because of the strong domain wall related ultrasound attenuation. The agreement between the MFA theory (the continuous line in the Fig. 2) and experiment is very good. 

Fig. 7.3 The resonance behavior of three different microcapsule formulations obtained by ultrasonic spectroscopy. The ultrasound attenuation (y-axis, given relative to the maximum) is measured over a driving frequency from 1 to 20 MHz (x-axis). Each capsule population has the same mean diameter of about 5 pm, but the shell thickness dif fers significantly (45, 105 and 236 nm). Tailoring the geometry of the USCA tunes the resonance properties. For example, increasing the...

Following Dukhin and McClements [26,27,30,31], let us give a brief description of each of these mechanisms of acoustic energy loss. A detailed theoretical treatment of acoustics is rather cumbersome, and will not be discussed here. We, however, will present the principal results of the ECAH theory when discussing different types of ultrasound attenuation below. 

We have analyzed the thermodynamic, magnetic and ultrasound attenuation data on oriented saaiples of the hlgh-T superconductors within the context of anisotropic Glnzburg-LSndau theory for coupled, even-parity superconducting states. We are able to present a consistent Interpretation of the data In terms of the coexistence of a quasi-two-dimensional d-wave state, with critical temperature T. - T and a more Isotropic mixed (s+d)-wave state with critical tempertaure T < T We predict the possibility of a "kink" in the temperature dependence of the lower critical field near 0 9T, which should be tested by experiments on single crystals. 

In practice, ultrasound attenuation is measured in decibel (dB) units, and hence UT attenuation in dB = 201ogjo Aq/A) (15.4)... 

Fig. 39. Temperature dependences of the transverse (312MHZ and q h, u c) and longitudinal (various frequencies and q, u b) elearonic ultrasound-attenuation coefficients of UPt, (Muller et al. 1986a). The most striking feature is the pronounced longitudinal attenuation peak at about 12 K, which is ascribed to a deformation-potential coupling to the heavy-fermion bands. The inset proves the quadratic frequency dependence of the longitudinal peak height as expected from theory, solid line (Muller and Bartell 1979).

The discussion of power laws has entailed the following experimental probes specific heat C(T) (fig. 77a-c), thermal conductivity k(T) (fig. 78a-c), spin-lattice relaxation rate by NMR T T) (fig. 79a-c), and ultrasound attenuation a(T) (fig. 80a-c), in addition to the penetration depth A(T) (fig. 76). The first three probes reveal information about the DOS of one-particle excitations in the superconducting state in the most direct way. 

Fig. 80. Temperature dependence of the ultrasound attenuation (a), a against T for longitudinal sound (1.7 GHz) at B = 0 and 2T in UBe,3 (Golding et al. 1985) (b), a against TIT for longitudinal (0.92 GHz) and transverse (0.67 GHz) sound at B = 0 in UPtj (Muller et al., 1986b) (c), a/a(T ) against TIT at B = 0 for transverse sound (0.132 GHz) along 6-axis with polarizations parallel to the a- and c-axes in UPtj. Solid lines in (c) are power-law fits to the entire data (Shivaram et al. 1986a).

Effect of static pressure on the phase 6.3.1. Ultrasound attenuation 132... 

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