Acoustic attenuation

Mud acoustic attenuation and annulus noise level are being investigated. It is expected that attenuation would be very sensitive to free gas concentration. 

Two outstanding properties of FeB metallic glasses are their low magnetic permeabilities and their low acoustic attenuations. The former results from their lack of magnetic anisotropy and has led to their use in power transformers, theft detectors, and various electronic devices. The latter results from the very low dislocation mobility in them. 

On-line particle sizing by ultrasonic (acoustic attenuation) spectroscopy was developed for use during batch crystallization processes.14 Crystallization of the alpha polymorph of (l) -glutamic acid from aqueous solution was monitored by continuously pumping the crystallizing solution through an on-line ultrasonic spectrometer. The method enabled measurement of the crystal size distribution and solid concentration throughout the... 

The ultrasound beam requires a medium to propagate from the transducer to the tissue. Water is the most convenient medium for this purpose, since its acoustic attenuation is small and the speed of sound and density are close to those in soft tissues. Thus, the ultrasound beam propagates almost completely undisturbed... 

Acoustic spectroscopy measures the speed and attenuation of sound waves interacting with a colloidal suspension. When a sound wave in the range of 1 to 100 MHz interacts with a colloidal suspension, the measured acoustic attenuation and... 

Two models are available for interpreting attenuation spectra as a PSD in suspensions with chemically distinct, dispersed phases using the extended coupled phase theory.68 Both models assume that the attenuation spectrum of a mixture is composed of a superposition of component spectra. In the multiphase model, the PSD is represented as the sum of two log-normal distributions with the same standard deviation, that is, a bimodal distribution. The appearance of multiple solutions is avoided by setting a common standard deviation to the mean size of each distribution. This may be a poor assumption for the PSD (see section 11.3.2). The effective medium model assumes that only one target phase of a multidisperse system needs to be determined, while all other phases contribute to a homogeneous system, the so-called effective medium. Although not complicated by the possibility of multiple solutions, this model requires additional measurements to determine the density, viscosity, and acoustic attenuation of the effective medium. The attenuation spectrum of the effective medium is modeled via a polynomial fit, while the target phase is assumed to have a log-normal PSD.68 This model allows the PSD for mixtures of more than two phases to be determined. 

Acoustic-absorbing material measurement of acoustic properties, 248 selection for underwater application, 248 Acoustic attenuation mechanisms mode conversion, 182-187 redirection of sound, 182 scattering of sound, 185-194... 

Pen Kem Acoustophor 8000 system (now Dispersion Technology) The system was extended for the measurement of sub-micron particle size distributions in concentrated slurries [238] which resulted in a prototype instrument, the Acoustophor Penn Kem 8000 system. This instrument consists of two flow-through cells for acoustic and electro-acoustic measurements respectively. With this system the acoustic attenuation is... 

Riebel and Ldffler [240] obtained an acoustic attenuation spectrum with one transducer pair to infer the particle size distribution. Solids concentrations and particle size distribution were obtained using both the Phillips-Twomey algorithm (PTA) and the relaxation method. The PTA gives a least squares solution by simple linear matrix operations to yield a numerical inversion from the attenuation spectra to the size distribution... 

In 1977 the National Materials Advisory Board (NMAB) of the National Academy of Sciences held a workshop on Acoustic Attenuation Materials Systems. The sponsoring agency was the Office of Naval Research, and the proceedings were published by the NMAB Conunittee on Structural Applications of Syntactic Foam (15). 

Proceedings of the Workshop on Acoustic Attenuation of Materials Systems, prepared by the National Materials Advisory Board (NMAB) Committee on Structural Application of Syntactic Foam, NMAB-339, 1978, 147 pp. 

Fig. 8 Idealised model of acoustic attenuation. A Diagrammatic representation of a thickness shear mode bulk acoustic wave resonator, coated with a rigid metal adhesion and electrode layer, a rigid chemical linker layer, a finite viscoelastic antibody receptor layer, a second adherent finite viscoelastic analyte layer, and finally a Newtonian liquid. B An idealised model of acoustic attenuation from bulk quartz through the above layers of varying viscosity, density, and shear modulus...

Dt, the thermal diffusivity 2/mpacp r, the acoustic attenuation coefficient cs, the adiabatic sound velocity... 

Acoustic attenuation in an aerogel until now was solely determined by acoustooptical techniques. The pulse-echo method proved not to be suitable for this purpose because of millimeter-sized inhomogeneities generally present in the material. 

---