No abstract available

[en] Full-Text: Crack that initiate and propagate in the materials can lead to ruptured and failure. Fatigue crack growth is the cracks that grow continuously by repeated actions. In monitoring crack growth using acoustic emission, there are several parameters that need to be taking into consideration which are count, count to peak, rise time, amplitude, energy count and frequency. The method use to simulated crack growth is pencil lead break (PLB) technique. In this paper, new calibration approached has been used in order to control the signal parameter. The PLB technique is applied at different distances on plate like structure and the waveform is captured by acoustic emission system which are developed by Agency Nuclear Malaysia. Post processing using Matlab has been performed in order to characterize the acoustic emission signal. (author)

[en] The main features of acoustic microscopy are reviewed. In particular the role of the lens and the instrument architecture are analyzed. Two typical outputs, i.e., digital images and V(z) curves, are discussed with reference to both their formation and their formation and their importance in acoustic analyses of materials. Examples of characterization of specimens are given, pointing out new methods based on non-destructive testing

[en] Basic terms of acoustic emission analysis are discussed. Some primary noise sources are mentioned, some aspects of application considered. (author)

No abstract available

[en] Scientific measurements of sound generation and radiation by musical instruments are surprisingly hard to correlate with the subtle and complex judgments of instrumental quality made by expert musicians

[en] A model-based approach is applied in the development of a processor designed to passively monitor an ocean acoustic environment along with its associated variations. The technique employs an adaptive, model-based processor embedded in a sequential likelihood detection scheme. The trade-off between state-based and innovations-based monitor designs is discussed, conceptually. The underlying theory for the innovations-based design is briefly developed and applied to a simulated data set

[en] Two properties of commercial microphones make it difficult or impossible to use them for studying shock waves in liquids which can easily be produced by spark discharges in dielectrics. On the one hand, these microphones have a marked resonance and on the other hand, it is not possible to shield the test signal sufficiently from electric and magnetic disturbances in the immediate vicinity of the spark discharge. Two types of microphones without these shortcomings have been developed. One type is a piezoelectric microphone which can be used for up to 5 MHz without resonance problems and the other is a magnetostrictive microphone with an acoustic delay line which can also be used for measurements at a distance of only a few millimeters from spark discharges. As a further advantage both microphones because of their small size only cause minimal disturbances to the sound waves. (orig.)

[en] Full-text: Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed Wavelet Transform analysis and Modal Location (WTML) based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup using H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) technique and DeltaTlocation. The results of the study show that the WTML method produces more accurate location results compared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure. (author)

[en] We designed and developed a confocal acoustic radiation force optical coherence elastography system. A ring ultrasound transducer was used to achieve reflection mode excitation and generate an oscillating acoustic radiation force in order to generate displacements within the tissue, which were detected using the phase-resolved optical coherence elastography method. Both phantom and human tissue tests indicate that this system is able to sense the stiffness difference of samples and quantitatively map the elastic property of materials. Our confocal setup promises a great potential for point by point elastic imaging in vivo and differentiation of diseased tissues from normal tissue