There are many advantages to adhesively bonding stiffeners onto aircraft structures rather than using traditional mechanical fastening methods. However there is a lack of confidence of the structural integrity of adhesively bonded joints over time. Acousto-ultrasonic Lamb waves have shown great potential in structural health monitoring applications in both metallic and composite structures. Thi...

In order fully to exploit energy of wind power the construction elements of the wind turbine should be inspected periodically. Ultrasonic air-coupled technique using guided waves has been selected for inspection of wind turbine blades, because only one side access is enough and no contact is needed. Dispersion curves of phase velocities as well as leakage losses versus frequency were calculated...

Out of the various existing ultrasonic power measurement techniques, the radiation force balance method using microbalance is most widely used in low power (below 1 W) regime. The major source of uncertainty associated with this technique is the error in ac voltage measurement applied to the transducer for the generation of ultrasonic waves. The sources that deteriorate the ac voltage measureme...

A nondestructive imaging method, scanning near-field ultrasound holography (SNFUH), has been developed that provides depth information as well as spatial resolution at the 10- to 100-nanometer scale. In SNFUH, the phase and amplitude of the scattered specimen ultrasound wave, reflected in perturbation to the surface acoustic standing wave, are mapped with a scanning probe microscopy platform to...

The literature on L forms of Proteus contains data derived from many cultural conditions and with different amounts of penicillin. It is difficult to evaluate conflicting reports unless the effect of environmental factors on the ability to form L type colonies can be put on a quantitative basis. This was done with the effect of media (Medill and O'Kane, 1954), and in the present paper attempts ...

The diffusive transport of multiply scattered ultrasonic waves is investigated experimentally and theoretically in a simple system consisting of glass beads in water. New experimental results are presented using a novel method for measuring the frequency correlation function of the transmitted acoustic field. The wave diffusion coefficient D is found to vary strongly with frequency when the wav...

An experimental technique for investigation of the behavior of acoustic wave propagation through a turbulent medium is discussed. The present study utilizes the ultrasonic travel-time technique to diagnose a grid-generated turbulence. The statistics of the travel-time variations of ultrasonic wave propagation along a path are used to determine some metrics of the turbulence. Experimental data o...

Diffuse ultrasonic signals received from ultrasonic sensors which are permanently mounted near, on or in critical structures of complex geometry are very difficult to interpret because of multiple modes and reflections constructively and destructively interfering. Both changing environmental and structural conditions affect the ultrasonic wave field, and the resulting changes in the received si...

A combined modeling and experimental study of acoustic cavitation bubbles that are initiated by focused ultrasound waves is reported. Focused ultrasound waves of frequency 335 kHz and peak negative pressure 8 MPa are generated in a water tank by a piezoelectric transducer to initiate cavitation. The resulting pressure field is obtained by direct numerical simulation (DNS) and used to simulate s...

An optimal statistical approach is applied to the task of image reconstruction in photoacoustics. The physical essence of the task is as follows: Pulse laser irradiation induces an ultrasound wave on the inhomogeneities inside the investigated volume. This acoustic wave is received by the set of receivers outside this volume. It is necessary to reconstruct a spatial image of these inhomogeneiti...