An analyzed object behaves as a selective band-pass filter [6] after the activation of pulse or after the formation of an acoustic emission. The recorded amplitude��s envelope is modified and the FFT (Fast Fourier Transform) [Figure 4(c)] is applied.The final power spectrum density (PSD) is then subjected to examination and modification. Some sellekchem vibrations (at certain frequencies) pass without significant changes, some are heavily suppressed. In order to work more synoptically with the received data, it is necessary to modify the PSD. After the application of the suggested filter, the irrelevant data are removed from the PSD and the result is saved in a matrix form [Figure 4(d)]. The suggested filter scans each pulse record (its PSD) and searches for specific values of the individual spectrum��s components.

Positions of points (their corresponding frequencies) are very important for the next analysis of the PSD. It is quite difficult to find these anomalies, because the signal spectrum has an odd shape [Figure 5(a)]. Hundreds of data which did not correspond to the distribution of maximums in the spectrum were received after the application of Inhibitors,Modulators,Libraries classic algorithm for finding the maximum (f(x?1) < max > f(x+1)). While searching for the cause of algorithm��s erroneous functioning, a simple cause was discovered. It is clear after enlarging part of the curve that it is not smooth. Modulated points created a number of false (pseudo) maxima [Figure 5(b)] which must be eliminated.Figure 5.(a) Detail of point in PS. (b) False maximum during application of simple algorithm for finding maximum.

The newly proposed filter (described further in the article) was able to eliminate these pseudo maxima. It went through the record Inhibitors,Modulators,Libraries and for the highest value in a certain area (local maximum) it verified whether it is really the highest. This interval is optional and its value is inversely related Inhibitors,Modulators,Libraries to the number of maxima in the record. Moreover, this interval may be expressed as insensitivity. Its value tells us in which interval a certain local maximum must be valid in order for its position to be clarified and saved. Furthermore, in order to remove the ubiquitous noise from the signal, the local maxima with amplitude smaller than 7% of the global maximum were eliminated. In this way the Inhibitors,Modulators,Libraries image was cleaned and sent to the next processing step with the assistance of a neural network. Work on the filter used is still in progress and by its improvement Cilengitide it is possible to achieve even better results.4.?Results and DiscussionA schematic of the during measurement series is depicted in Figure 6. Vibrations are scanned with the assistance of a type 4332 accelerometer from Bruel & Kjaer. This sensor is unique for its high frequency range, which exceeds 25 kHz.