Showing papers in "Ultrasonics in 1998"

TL;DR: In this paper, the authors present a review of the studies of the propagation of the waves and their sensitivity to defects which have been conducted in order to provide a sound scientific basis for the method.

TL;DR: In this article, the second-order acousto-elastic coefficient (SOC) was measured in a variety of materials including plastics, metals, composites and adhesives.

TL;DR: The results of experimental investigation of acoustic non-linear phenomena on contact boundaries are presented in this article, where simulation experiments demonstrated a threshold nonlinear distortion due to "clapping" and "kissing" mechanisms, multiple bifurcations and chaos development for contact vibrations.

TL;DR: A comparison of the usability of different wave types is presented in this article, where planar technologies are used for fabrication of the acoustic-wave devices, which will be given of gas sensors, biochemical sensors in liquids, viscosity and density sensing and highvoltage sensing.

TL;DR: A description is given of its various scientific and engineering applications, including the study of wave dispersion in structures, global and long-range inspection of steel pipes and tubes, condition monitoring of machinery such as combustion engines, and onboard sensing of crash events for vehicle safety system operations.

TL;DR: In this paper, the Lamb wave propagation in large plates and its use in internal defect detection have been studied and the Lamb modes which are most efficient for detecting different types of internal defects are identified.

TL;DR: In this article, the authors present a model and subsequent solution to a boundary value problem that can evaluate the source influence as a function of the comb transducer design parameters, along with an insight into future directions.

TL;DR: The aim of the project partially presented here is the development and validation of an example of a Doppler test object fulfilling the requirements of the IEC 1685, and very precise recipes have been developed for the composition and preparation of both TMM and BMF.

TL;DR: By applying these methods, it has become possible to take the AE signal from the rotating tools and in terms of AE signal processing for identifying the machining processes, application of the artificial neural network will be introduced.

TL;DR: In this paper, a machining process with the superimposing of ultrasonics is considered and the accumulated experimental results are explained theoretically in the framework of rheological models.

TL;DR: Harmonic imaging is a new contrast-specific imaging modality, which utilizes the nonlinear properties of some agents in an attempt to alleviate current limitations of ultrasound contrast studies.

TL;DR: In this article, it is shown that the kissing bonds can be effectively detected by some leaky Lamb mode, and the theoretical and experimental results are presented to show that using the Lamb waves is an effective way of detecting kissing bonds.

TL;DR: In this article, the influence of element width on the ultrasonic beam steering properties was investigated and the beam directivity patterns were analyzed and used as the criteria for determining optimal transducer design parameters.

TL;DR: In this paper, a film shot at 500 frames s −1 shows the acoustic stable and transient cavitation activity in a stationary field at 28 kHz frequency, where stable cavities are simply bubbles that oscillate, often non-linearly, around some equilibrium size during many cycles of acoustic pressure.

TL;DR: In this paper, the authors reviewed the phenomena involved in the creation of electric signals by ultrasound in aqueous solutions of electrolytes with special reference to the acousto-electric interaction signal resulting from the local, periodic conductivity changes produced by the propagation of a pressure wave.

TL;DR: In this paper, the authors used linear acoustic equations and fluid dynamics equations to predict acoustic cavitation fields in a cylindrical sonoreactor at 28 and 500 kHz and showed good agreement with both theory and calculations.

TL;DR: Ordered band formation was preserved by the laminar flow in the expansion chamber, although bands that formed very close to the wall were dissipated downstream, and the microscopy chamber provided evidence of significant lateral particle concentration within bands in the pressure nodal planes.

TL;DR: In this article, the authors examined the rate of free radical production of the MTS system under different conditions of temperature, pressure and ultrasound amplitude using the terephtalate dosimeter.

TL;DR: An algorithm to detect grey level transitions with multiple scales of resolution to improve edge detection and localisation in ultrasound images of the prostate is investigated, illustrating an edge detection method suitable as pre-processing step in interpretation of medical images.

TL;DR: In this article, the phase velocity and attenuation of Lamb modes are measured and compared with numerical predictions, and it is shown that the air-coupled transducers can be used for NDT applications of materials.

TL;DR: In this article, a micro particle trapping system based on the opposite phases ultrasonic traveling waves is proposed, which is carried out by polystyrene spheres and some characteristics of the method, such as size of the micro particles trapped inside the flow and phase error between two ultrasonic waves, are discussed.

TL;DR: In this article, an ultrasonically energized polishing process, suitable for the polishing of complex dies and moulds has been successfully developed and patented, which is based upon the combination of the two "non-traditional" techniques of abrasive flow machining and ultrasonic machining.

TL;DR: In this paper, the kinetic equation of evaporation and condensation of water vapour at the bubble wall is calculated numerically in order to investigate the non-equilibrium effect of nonequilibrium effects.

TL;DR: In this paper, the influence of the technological parameters on the surface hardening of metals by ultrasonically accelerated small balls was evaluated, and the experimental results showed that the ultrasonic impact treatment of steel might be used in industrial scale.

TL;DR: In this paper, the authors measured the acoustic properties of the contrast agent and compared them with those of the myocardium, showing that the difference between scattering of the Myocardium and scattering of intravenously injected Albunex is too slight to be visible on an echographic image.

TL;DR: In this article, a new technique called material characterization by resonance acoustic spectroscopy (MCRAS) is introduced for the evaluation of the elastic constants of isotropic rods and wires, compared to the traditional time-of-flight measurement technique.

TL;DR: In this paper, a SiGMA (simplified Green's function for moment tensor analysis) code is developed to determine moment tensors components in ultrasonic waveforms to determine time-of-flight information.

TL;DR: In this paper, the authors reported measurements of diffusivities and absorption in other materials, particularly in metallic polycrystals, as well as measurements of modal densities for the high-frequency regime.

TL;DR: In this article, a laser impact of short time duration is used to create a point source of Lamb waves and the detected waves are then remitted, but in time reverse order, according to this reemission, they obtain an axial hyperfocusing effect whose maximum is localized at the initial laser generation point.

TL;DR: Three-dimensional ultrasound imaging techniques that are capable of acquiring B-mode, colour Doppler and power Dopplers images of the vasculature are developed by using a conventional ultrasound system to acquire a series of two-dimensional images and then mathematically reconstructing them into a single three-dimensional image, which may then be viewed interactively on an inexpensive desktop computer.