Showing papers in "Ultrasonics in 2001"

TL;DR: A truly universal correlation is proposed which accounts for the effects of physico-chemical properties of the liquid, and ultrasonic properties like amplitude, frequency and the area of vibrating surface, and takes cue from the conventional numbers that define the significance of different forces involved in droplet formation.

TL;DR: The numerical instability problem in the standard transfer matrix method has been resolved by introducing the layer stiffness matrix and using an efficient recursive algorithm to calculate the global stiffness matrix for an arbitrary anisotropic layered structure.

TL;DR: Capacitance transducers were used to generate wide bandwidth swept-frequency signals in air, which were then used to measure and image solid samples in through transmission, demonstrating that such signal processing techniques lead to an improvement in the signal to noise ratio and timing accuracy for air-coupled testing.

TL;DR: This work describes the iterative reconstruction procedure developed for Lamb wave tomography and allowing for ray bending correction for imaging of moderately scattering objects.

TL;DR: In this paper, the propagation and scattering of ultrasound in concrete is discussed, and the ultrasonic energy density in circular cylinders of concrete is shown to evolve in accordance with a one-dimensional diffusion equation.

TL;DR: In this article, the effects of the inner and outer media have been investigated by considering a copper pipe with air or water on both the inside and outside of the pipe, and the effect of viscosity has also been demonstrated for a castor oil-filled copper pipe in air.

TL;DR: Aluminium sheet thickness has been calculated from ultrasonic data obtained using a send-receive, radially polarised electromagnetic acoustic transducer (EMAT) using the most accurate measurements made using Fourier analysis and have yielded measurements accurate to within 0.2% for 280 microm thick aluminium sheets.

TL;DR: The velocity of propagation, attenuation and viscoelastic moduli have been evaluated for both compressional and shear ultrasonic waves in the interval 2-10 MHz for doughs of different hydrations.

TL;DR: In this paper, the amplitude spectra of two additional pulses reflected back from the front and back surfaces of the specimen is used to estimate the thickness and attenuation of the transmitted signal.

TL;DR: Particle image velocimetry was used to investigate ultrasound-induced acoustic streaming in a system for the enhanced uptake of substances from the aquatic medium into fish, and a positive linear relationship was found between the ultrasound intensity and the maximum streaming velocity.

TL;DR: In this article, the influence of a viscous or conductive liquid on the characteristics of acoustic waves propagating in thin piezoelectric plates is investigated theoretically as well as experimentally.

TL;DR: It is found that at normal imaging pressures, ST68 agent-generated second harmonic enhancements dropped to approximately 8 dB at 100 kPa and approximately 2 dB at 1 MPa, while at these pressures water (or tissue) produced strong second harmonics due to non-linear propagation.

TL;DR: In this article, an ultrasonic measurement procedure that exploits the nonlinear transfer of ultrasound to distinguish between strong and weak bonds is presented, and the theoretical fundamentals of this technique are described; a measure of the bond strength of an adhesive joint and a calibration procedure are derived.

TL;DR: The piezotransducers employed in high power ultrasound are composed of piezoelectric ceramics and metallic pieces and the resonance and anti-resonance frequencies are shifted depending on the level of applied mechanical pre-stressing.

TL;DR: The method allows simultaneous determination of the coating thickness, density, elastic moduli and attenuation (longitudinal and shear) from normal and oblique incidence reflection (transmission) frequency spectra.

TL;DR: Performances estimation of the piezoelectric rotary traveling wave ultrasonic motor as a function of input voltage amplitude and driving frequency and preload is presented.

TL;DR: An ultrasonic method of acoustic parameter evaluation for porous materials saturated by air or any other gas, based on the evolution of speed of sound and the attenuation inside the material when the static pressure of the gas saturating the material is changed, is discussed.

TL;DR: The results suggested that the low-level ultrasound could enhance the cytotoxicity of adriamycin to human ovarian carcinoma cells and promoted intracellular drug contents played the leading role.

TL;DR: A high power resonance tracking ultrasonic amplifier configured as a half-bridge in which the output MOSFETs are driven into saturation when on offers some advantages over phase locking and motional feedback methods.

TL;DR: A mathematical model is described to explain the effect of shifts on resonance and anti-resonance frequencies based on difference of effective cross-section between transducers parts under pre-stressing and a proportional relation between pre-Stressing and effective coupling of the parts is shown.

TL;DR: By using short ultrasound bursts a distance may be indicated that beyond which the contributions of transducer reflections on the phase of the propagating wave may be neglected, and the contention that for reasonably small incident angles, reflection within the skull causes minimal phase shift is supported.

TL;DR: The merits and limitations of the different techniques of measurement covering the frequency range from 10 kHz up to nearly 10 GHz now, corresponding with relaxation times between about 0.1 ms and 100 ps, are discussed.

TL;DR: In this paper, the authors investigated how by fine-tuning the frequency and the striking angle of the incident beam in the neighborhood of a Lamb mode one can separately detect internal defects in layers of mirror symmetry in the upper and lower halves of a plate.

TL;DR: The "double-driver" cymbal, a directional class V flextensional transducer, is described in this paper to demonstrate that under optimal conditions the array can provide a directional beam pattern with a front-to-back ratio of more than 20 dB.

TL;DR: In this paper, an analytical model for the generation of bulk and surface acoustic waves at the surface of an isotropic solid by an infinite thermoelastic laser line source is developed.

TL;DR: This paper presents a new method of measuring dispersion curves of leaky Lamb waves propagating in a thin plate based on a lens-less line-focus transducer and its defocusing measurement technique and a new waveform processing method known as V(f, z) method for analyzing the measured waveforms and for extracting the dispersion relation.

TL;DR: A method for simultaneously measuring the sound propagation velocity and the thickness of each wall on the opposite sides of a tube is presented and results of measurements on five tube samples are reported.

TL;DR: Experimental results of the interaction of thin layers of lead phthalocyanine (PbPc) with trace amounts of toxic gas NO2 in a system with an acoustic surface wave on a LiNbO3 Y-Z substrate are presented.

TL;DR: A theoretical model is presented to estimate the optimal frequency-to-bandwidth of the Gaussian wavelet in ultrasonic non-destructive evaluation, and the experimental results confirm the availability of the theoretical model.

TL;DR: Particle image velocimetry (PIV) is applied for the first time to study Eckart streaming induced by a medical ultrasonic transducer and serves as a prelude to investigations of streaming in biological type fluids.