Hybrid Topological Derivative-Gradient Based Methods for Nondestructive Testing

Figure 10

Reconstruction of sound-soft objects. (a) Topological derivative when Ω=∅. (b) Initial guess Ω₀ superimposed to the topological derivative for Ω=Ω₀. (c)-(d) Approximate domains Ω_𝑚 superimposed to the topological derivative for Ω=Ω_𝑚, for 𝑚=1 and 𝑚=2. (e) Final reconstruction of the objects after 13 steps (dashed red line).

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