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Showing papers in "Ultrasonics in 1994"


Journal ArticleDOI
TL;DR: In this paper, the acoustic behavior of an ideal gas bubble in water is considered and the equation of motion is extended to model an Albunex microsphere, which reveals large differences in non-linear behaviour between ideal gas bubbles and the microspheres.

367 citations


Journal ArticleDOI
TL;DR: In this paper, the level of second-harmonic response is about 20 dB below the first harmonic at an acoustic pressure amplitude of 50 kPa, and it is demonstrated that, under controlled conditions, it is possible to discriminate between Albunex and other scattering/reflecting objects using the non-linear behaviour of the microspheres.

206 citations


Journal ArticleDOI
TL;DR: In this article, a Lamb wave immersion tomography technique was used to image damaged regions in two polymer composite plate samples, which had been previously loaded in a biaxial test method until failure.

84 citations


Journal ArticleDOI
TL;DR: In this paper, a theoretical investigation of the use of normal incidence ultrasonic reflection measurements for the detection and characterization of thin layers embedded between two much thicker media has been carried out, and it has been shown that the relationship between the normal incidence longitudinal reflection coefficient and frequency is defined by the reflection coefficients at zero frequency and at half the resonance frequency of the layer.

79 citations


Journal ArticleDOI
TL;DR: The degree of tissue change ranged from the induction of stress fibres and intercellular gaps to the complete detachment of endothelial cells combined with damage of the basement membrane, which might explain the enhanced effects in experimental tumour therapy that have been found by other authors when combining shock-waves with drugs.

78 citations


Journal ArticleDOI
TL;DR: In this article, the attenuation coefficients of anisotropic wood were measured with the through-transmission technique and some experimental factors that can affect the determination of attenuation coefficient were related to the geometry of the radiation field, and to the scattering and absorption of ultrasonic energy by the solid.

78 citations


Journal ArticleDOI
TL;DR: In this paper, a fractionation method for fine-particle suspensions based on variations in the speed of response to ultrasonic standing wave fields has been developed, which is sensitive to a combination of the particle size and suspending fluid density and compressibility.

55 citations


Journal ArticleDOI
TL;DR: In this article, the sonoluminescence spectra of argon-saturated water were studied in the 210-500 nm wavelength region at 1.1 MHz, 337 kHz and 22 kHz ultrasound frequencies in the 11°C-70°C temperature interval.

53 citations


Journal ArticleDOI
TL;DR: In this paper, an automated laser-based ultrasound system is described that has sufficient sensitivity to detect typical flaws of interest in composite materials without causing surface damage to the part under test.

45 citations


Journal ArticleDOI
TL;DR: In this article, a line-focus acoustic microscopy has been used to determine local near-surface stresses in isotropic materials and the measured stresses are in good agreement with the results calculated by a finite element method.

44 citations


Journal ArticleDOI
TL;DR: In this article, the extraction of tea solids with water under the influence of ultrasound has been studied with respect to the effects of temperature, irradiation time and power Sonication improved the extraction at 60 °C by nearly 20%, approaching the efficiency of that of thermal extraction at 100 °C.

Journal ArticleDOI
TL;DR: After the application of shock waves, cavitation-generated free radicals are demonstrated in cell-free solutions and also in the surviving and intact suspended MGH-U1 cells by hydroethidine measurements and under electron microscopical inspection.

Journal ArticleDOI
TL;DR: A new type of probe is presented, which combines an ultrasound receiver constructed from piezoelectric polymer materials with a coaxial optical fibre for laser-induced ultrasound for intra-arterial imaging and therapy.

Journal ArticleDOI
TL;DR: In this paper, the transducers and the matching layer are treated as a passive layer system which is irradiated with four special waves and these four waves can be combined to one wave with a frequency dependent amplitude.

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional fast Fourier transform (FFT) was used to obtain the dispersion curves of the plate, in wave-number and frequency, which can be used to determine which modes propagate in the structure as well as their relative amplitudes.

Journal ArticleDOI
TL;DR: In this article, the electric impedance of a thin piezoelectric disc can be simulated by using two one-dimensional models, and the validity of such models is verified by comparing the theoretical and experimental electrical impedances obtained when the ceramic is placed in different viscoelastic media.

Journal ArticleDOI
TL;DR: In this article, a method for solving the direct problem of acoustical thermography in the one-dimensional case is proposed for theoretical calculations of the acoustobrightness temperature Ta on an object's surface from the distribution of the thermodynamic temperature and the absorption coefficients within the surface.

Journal ArticleDOI
TL;DR: In this article, breakdown-generated sound pulses in air were studied in the zero to 200 kHz frequency range and theoretical predictions, based on a theory originally developed for macroscopic blast waves, were used to predict peak sound pressure, power spectra and pulse peak-to-peak time.

Journal ArticleDOI
TL;DR: Using a stroboscopic photoelastic method, the visualization of various mode patterns of Lamb waves propagating in a glass plate was carried out in this paper, where the experimental results were in good agreement with theoretical curves.

Journal ArticleDOI
TL;DR: In this article, a mathematical model that predicts changes to the ultrasound frequency spectrum after passing through human tissue and Albunex microspheres is proposed, which enables one to explain and predict clinically observed intensity effects such as the shadow effect in the right ventricle, and the fact that received intensity increases with concentration up to a certain point where it falls off.

Book ChapterDOI
TL;DR: In this article, a broadband EMAT was used to probe bond integrity in a broadband, true pulse-echo mode, and the most attractive feature of the EMAT used in this work is that it generates radially polarised SH waves which should be more sensitive than longitudinal waves at normal incidence to a bonded interface.

Journal ArticleDOI
TL;DR: In this paper, an investigation into methods of producing ultrasonic phased arrays resonating at 100 kHz using capacitive transducers is described, and several arrays with both λ and λ 2 element spacings were produced and tested.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the torsional vibration of the tangentially polarized piezoelectric ceramic slender tube and derived its electromechanical equivalent circuit based on the network theory.

Journal ArticleDOI
TL;DR: In this paper, the Stroh-Barnett integral formalism of surface waves in anisotropic solids was used to calculate the variation of surface wave speeds of a unidirectional fiber-reinforced composite in an efficient way.

Journal ArticleDOI
TL;DR: In this article, the potential efficiency of high power ultrasonic transducers was investigated and an optimum design of the sandwich transducer which maximizes the potential energy efficiency and minimizes the effect of the contacting loss on the transducers resonant frequency was proposed.

Journal ArticleDOI
TL;DR: In this article, a computerized algorithm, utilizing pulse-echo data, which permits simultaneous velocity and thickness determination is presented. But the accuracy of the algorithm is limited to 2% when compared with direct mechanical measurements.

Journal ArticleDOI
TL;DR: In this paper, the applicability of a relatively low-power laser in generating detectable ultrasound for a sensing application was confirmed and temporal shapes of low power photoacoustic sound sources were predicted and measured.

Journal ArticleDOI
TL;DR: In this paper, the authors presented the velocity and mass sensitivity formulae in explicit form for shear-horizontal (SH) plate wave sensors, where the mass loading layer is assumed to be acoustically thin (h ≪ λ), where h is the acoustic wavelength.

Journal ArticleDOI
TL;DR: In this paper, the authors used a small wideband (0.1-20 MHz) piezoelectric hydrophone for the measurement of photoacoustically induced ultrasonic waves in liquids with low optical absorption.

Journal ArticleDOI
TL;DR: In this paper, a model-based approach is presented for estimating the average power spectrum associated with backscattered grain noise, which can be useful in assessing the probability of flaw detection and in suppressing the noise in order to enhance flaw detection.