Long defect

Elaboration of a Physical Model by Eddy Current and Application in the Characterization of Long Defects in Hollow Cylindrical Products. 

The more dangerous defects will be flat defects perpendicular to the current lines. In two dimensions they are lines, but in three dimensions they have the shape of cylinders. Prom the results of Section 1.2.2(a), one can see that the enhancement factor for an elliptic defect (see Fig. 2.4) is k = l/b. Thus a long defect parallel to the current lines b I ) does not affect the current lines, while a long defect perpendicular to the current line b 1) affects them strongly. 

The enhancement factor of the field near a long defect (made of n Cq capacitors) perpendicular to the electrodes is given by... 

The probability to find a long defect made of n Cq capacitors is... 

For a long time, the wheels were mainly tested with dye penetration. This test procedure can make defects which are open to the surface of the material visible for the tester. It is, however, common knowledge that the test results vary greatly depending on the subjective view of the individual tester. 

It would be tlierefore thus easy to obtain in real time, on computer, tlie image of a long standard defect that is to even to produce the impedance variation observed. It would be thus possible to realize the control by absolute measures and to avoid the recourse to standard defects. 

The effect of a long axial rectangular emerging defect of width e and of depth h is to increase the section Sa between the solenoid and the tube value of AS = eh. The induction in the space between the solenoid and the external surface of the tube and inside of tube remains unchanged. 

If we suppose that the presence of a long axial emerging rectangular defect doesn t change the thickness e of the ring where the induction in the tube is not equal to zero but only its circumferential length, and also that it is it does not change the local induction in amplitude and phase, then the presence of the defect increases only the of the piece where the induction is not equal to zero, this increment is equal to 2he. 

The inductance variation measure with a defect long than the coil length permit to calculate the defect surface. 

Figure 8 Sensitivity of the new photothermal camera to small depth defects. lmage of an EDM notch of 1mm long, 100 pm width and 200 pm depth on ANSI 304 stainless steel with a bad surface condition (ground surface, "Vi 2 -6 ).

Our near future improvements include automatic defect detection and reporting, and integration of reports into Word or Excel documents. On the long nin, automatic comparison with historical data will be possible, and if acquisition cards improve, acquisition may be perfomied by the analysis tools. 

The situation is very different in indirect gap materials where phonons must be involved to conserve momentum. Radiative recombination is inefficient, resulting in long lifetimes. The minority carrier lifetimes in Si reach many ms, again in tire absence of defects. It should be noted tliat long minority carrier lifetimes imply long diffusion lengtlis. Minority carrier lifetime can be used as a convenient quality benchmark of a semiconductor. 

The defects generated in ion—soHd interactions influence the kinetic processes that occur both inside and outside the cascade volume. At times long after the cascade lifetime (t > 10 s), the remaining vacancy—interstitial pairs can contribute to atomic diffusion processes. This process, commonly called radiation enhanced diffusion (RED), can be described by rate equations and an analytical approach (27). Within the cascade itself, under conditions of high defect densities, local energy depositions exceed 1 eV/atom and local kinetic processes can be described on the basis of ahquid-like diffusion formalism (28,29). 

Most of the AHoy 600 outer diameter tube corrosion has occurred in the region of the upper tubesheet near the open lane, ie, an untubed lane across the middle of the steam generator (16,17). The steam carries entrained droplets of water through the open lane to the upper tubesheet region where the droplets dry out and concentrate the chemicals. Long tube inserts have been used to sleeve tubes in this region where wall defects have been detected. 

Receptor Regulation and Defects. Specific recognition and the initiation of response are the accepted attributes of the dmg—receptor interaction. However, target cells can alter on both short- and long-term time scales their sensitivity to dmgs. Such regulation, achieved by altering the... 

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