Hybrid Topological Derivative-Gradient Based Methods for Nondestructive Testing
Figure 6
Comparison of the alternative definitions of the topological derivative inside an object and of the monotone and nonmonotone methods. (a) Topological derivative when . (b) Initial guess (dashed lines) superimposed to the topological derivative for using the extended definition (21) inside . (c) Counterpart of (b) using the extended definition (26). (d) Final reconstruction at the 11th iteration using the non-monotone method (dashed red line). (e) Final reconstruction at the 9th iteration using the monotone method (dashed red line). (f) Evolution of the cost functional applying the non-monotone strategy.
