Abstract: A method for imaging a structure composed of at least one wave guide connected to a junction, the structure supporting elastic wave guided propagation modes, the method includes the following steps: for at least one operating frequency, acquiring a plurality of measurements of signals propagating in the structure by means of a plurality of pairs of non-colocalized elastic wave sensors, determining a plurality of propagation modes guided by the structure, correcting the measurements on the basis of ultrasound signals measured or simulated for the same structure in the absence of any defect, converting the measurement matrix M into a wave field scattering matrix U, determining, at each point of a sampling grid, a test vector F characteristic of the structure without any defect, applying a numerical inversion method to determine a vector H of modal components such that U.H=F at each point of a sampling grid, determining an image of the structure on the basis of the vector H.

Abstract: This method comprises: a step of reconstructing the acoustic signal produced during the occurrence or the evolution of the defect, this reconstruction step comprising constructing an estimate Se(w) of the signal produced at the position of the defect based on an ultrasonic signal Fj(t) measured by a sensor and using an estimate or a measurement of a product Rj(w)Gj(w) that relates, in the frequency domain, the measured ultrasonic signal Fj(w) to the produced acoustic signal S(w), and a step of automatically classifying the acoustic source, carried out based on the estimate of the reconstructed acoustic signal.

Abstract: A method for imaging a structure composed of at least one wave guide connected to a junction, the structure supporting elastic wave guided propagation modes, the method includes the following steps: for at least one operating frequency, acquiring a plurality of measurements of signals propagating in the structure by means of a plurality of pairs of non-colocalized elastic wave sensors, determining a plurality of propagation modes guided by the structure, correcting the measurements on the basis of ultrasound signals measured or simulated for the same structure in the absence of any defect, converting the measurement matrix M into a wave field scattering matrix U, determining, at each point of a sampling grid, a test vector F characteristic of the structure without any defect, applying a numerical inversion method to determine a vector H of modal components such that U.H=F at each point of a sampling grid, determining an image of the structure on the basis of the vector H.