Abstract: Disclosed are a method and device for compressing and reconstructing data. The method includes: disposing a transmitting EMAT array and a receiving EMAT array; exciting a Lamb wave, receiving the Lamb wave, subjecting the Lamb wave to narrowband filtering with the narrowband frequency, to form detecting data x(n); analysing the detecting data with a DFT; reconstructing original detecting data and calculating a reconstruction error according to the measurement vector and the recovery matrix by using a TLBO algorithm; optimizing measurement vector and recovery matrix; transmitting the measurement vector to a supervisory device.

Abstract: A method for detecting a defect of a metal plate includes selecting N controllable emitting electromagnetic acoustic transducers EMATs as excitation transducers, and selecting M omnidirectionally receiving EMATs as receiving transducers, exciting an ultrasonic guided wave in a metal plate by a nth controllable emitting EMAT with a predetermined emission angle; determining whether each of M1 omnidirectionally receiving EMATs and the nth controllable emitting EMAT form a scattering group; for the scattering group, solving a position of a scattering point and a direction of a scattering side according to a distance between Tn and Rml, the emission angle and a travel time of the ultrasonic guided wave; performing a curve fitting on all the scattering points in directions of respective scattering sides to obtain a contour image of the defect.