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Table 1 Comparative between the amount of information and added noise. For six linearly-spaced frequencies between 0.8 and 2 Hz we present in the first row the maximum amplitude of a thermogram, on the second row the maximum amplitude of the difference between the thermogram of a faulty plate and the one corresponding to a healthy one, that is the amount of useful information, and on the last row the quotient between the added noise and that amount of information. For the considered frequency range, this ratio decreases as we increase the frequency

From: Application of the topological derivative to post-processing infrared time-harmonic thermograms for defect detection

Frequency [Hz]

0.80

1.04

1.28

1.52

1.76

2.00

\(\max (|\mathcal{T}^{\mathrm{front}}| )\) [K]

0.521

0.418

0.356

0.316

0.288

0.268

\(\max (|\mathcal{T}^{\mathrm{front}}_{\mathrm{faulty}}-\mathcal{T}_{\mathrm{healthy}}^{\mathrm{front}}| )\) [K]

0.058

0.050

0.045

0.044

0.041

0.038

ratio noise to information

90%

83%

79%

72%

70%

70%