Digital processes

It allows to save the radiographic film in computer for an eventual digital processing. In our case welded joints radiographic films are digitized in 256 gray levels. 

To evaluate the performance of digitization, we compared conventional procedure and digital processing by the mean of a specimen made of steel and composed of various electro-eroded slots (figure 1). The obtained perceptibility is dependent on both the width and the depth of the slots. 

Finding the values of G allows the determination of the frequency-domain spectrum. The power-spectrum function, which may be closely approximated by a constant times the square of G f), is used to determine the amount of power in each frequency spectrum component. The function that results is a positive real quantity and has units of volts squared. From the power spectra, broadband noise may be attenuated so that primary spectral components may be identified. This attenuation is done by a digital process of ensemble averaging, which is a point-by-point average of a squared-spectra set. 

Fig. 13.13 Photographs of sonoluminescence from NaCl aqueous solution sonicated at 135 kHz in a cylindrical beaker (a). Image (a) was digitally processed to obtain the red component (b), which corresponds to Na atom emission, and the blue component (c), which corresponds to continuum emission [41] (Reprinted from the Japan Society of Applied Physics. With permission)...

Dizhur EM, Fedorov AV (2004) Digital processing in tunneling spectroscopy. arXiv cond-mat/0408206v2... 

Rabiner and Schafer, 1978a] Rabiner, L. and Schafer, R. (1978a). Digital Processing of Speech Signals. Prentice Hall, Englewood Cliffs, NJ. 

Huang, H.K., Meyers, G.L., Martin, R.K., Albright, J.P. (1983). Digital processing of microradiog-raphic and fluorochromic images from bone biopsy. Comp. Biol. Med. 13,27-47. 

In order to actually carry out time resolved spectroscopy, the gating process must be synchronized to both the experiment and the reading and digitizing processes. This is not trivial but can be done using additional logic and timing circuits (see, for example, ref. 107). 

Digital Processing of the Free-induction, Decay Signal. 50... 

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