Acoustic emission is an effective method of locating the rubbing fault. In order to solve the problem that satisfactory location accuracy is difficult to obtain because of the waveform distortion caused by signal propagation during the application of time delay estimation method in acoustic emission position estimation, beam-forming technique is applied to acoustic emission source location. Sim...

Acoustic emission is an emerging technique for condition monitoring of rolling element bearings and potentially offers advantages for detection of incipient damage at an early stage of failure. Before such a technique can be applied with confidence for health monitoring, it is vital to understand the variation of acoustic emission generation with operating conditions in a healthy bearing. This ...

We have used pulse time-of-flight techniques to examine the phonon emission from an optically excited GaAs/AlAs superlattice structure. For laser excitation wavelengths shorter than 767 nm ~the energy of E1HH1 transition!, we detect a significant longitudinal acoustic phonon component directed in a narrow beam normal to the structure. Under identical excitation conditions, generation of coheren...

Radiation from relativistic runaway electrons is considered as a source for plasma frequency radiation in tokamaks. Two specific emission mechanisms, Cerenkov emission, and radiation produced by nonlinear coupling of plasma and acoustic waves, are studied. In many cases the Cerenkov emission provides a reasonable spectral fit. It can also be used to measure the runaway current, and to est'imate...

Introduction Transverse matrix cracking in cross-ply gr/ep laminates was studied with advanced acoustic emission (AE) techniques. The primary goal of this research was to measure the load required to initiate the first transverse matrix crack in cross-ply laminates of different thicknesses. Other methods had been previously used for these measurements including penetrant enhanced radiography, o...

The physics of ultrasonic acoustic emissions ( A E s ) was investigated for AE transmission through w o o d and transducers. The physical properties measured were velocity, attenuation and frequeney composition ol" AEs produced by two sources: cavitation events in xylem and peticil lead breaks. T h e authors also measured the relative sensitivity of var ious combinations of ultrasound transduce...

Japanese Industrial Standard (JIS) Z 2342 was revised significantly in 2002. The original standard was enacted in 1991 with the title, "Method for acoustic emission testing of pressure vessels during pressure test". The title was also changed, based on NDIS2412 “Acoustic Emission Testing of Spherical Pressure Vessel Made of High Tensile Strength Steel and Classification of Test Results”, which ...

Prompted by intriguing events observed in certain particle-physics searches for rare events, we study light and acoustic emission simultaneously in some inorganic scintillators subject to mechanical stress. We observe mechanoluminescence in Bi4Ge3O12, CdWO4, and ZnWO4, in various mechanical configurations at room temperature and ambient pressure. We analyze the temporal and amplitude correlatio...

With the heater pipeline leakage experiment conducted on the experiment table, inner pipeline leakage of heater was studied through the leakage failure detection system. The frequency distribution and the amplitude of acoustic emission signals of leakage versus internal pressure were analyzed. Variations of signals versus leakage aperture and dissemination distance were summarized. According to...