Séminaire

Titre :	Long Li (CAS, China). Research on the inverse acoustic scattering problems in inhomogeneous media
Contact :	Marcella Bonazzoli
Date :	14/03/2023
Lieu :	10h30, Zoom link

Séance exceptionnelle de séminaire en ligne IDEFIX-POEMS. Join Zoom Meeting: https://us06web.zoom.us/j/87385938835?pwd=Q2lHU3NJN2R3dElCSFZNRXpCcnMzdz09 Abstract: The first part of this talk concerns the inverse scattering problem of time-harmonic acoustic plane waves in a two-layered medium in dimension two. To recover buried obstacles in the lower half-space of the two-layered medium, a direct imaging method is developed, which can locate positions of small anomalies with only the intensity of the far-field pattern measured in the upper half-space. Combining this algorithm, a recursive Newton-type iteration algorithm in frequencies is proposed to reconstruct both the location and shape of extended obstacles. When the interface of the two-layered medium is unknown and locally rough, a direct imaging method is considered to reconstruct the penetrable locally rough interface using the phaseless total-field data which are only measured on the upper part of the circle with a sufficiently large radius. Moreover, a similar direct imaging method is developed to reconstruct the penetrable locally rough surface from the phased far-field data measured on the upper part of the unit circle. The second part of this talk concerns the non-scattering phenomenon. A rather weak condition on scattering interfaces and refractive index functions is provided to guarantee the scattering phenomena that the scattered fields cannot vanish identically. Local uniqueness is obtained for the inverse medium scattering problems with only a single far-field pattern known.