2 results about "Guided wave propagation" patented technology

This invention relates to the field of icing and snow accumulation detection technology, and discloses a method and system for detecting icing on overhead transmission lines. The method includes: deploying integrated torsional vibration and acoustic emission sensing units at both ends of the transmission line span to collect conductor angular velocity and acoustic emission signals; performing cross-correlation processing on the angular velocity signals within a time window to obtain the propagation delay of multi-band torsional guided waves, and calculating the group velocity in conjunction with the span length; comparing the group velocity with a baseline curve for an ice-free period, and inverting the icing thickness using a composite pole dispersion model; using the acoustic emission signals to detect sudden events; if the number and energy of events exceed a threshold and the group velocity rebounds, it is determined to be an icing shedding state; otherwise, it enters the thickness and event fusion stage, outputting the icing thickness, growth rate, icing shedding alarm, and confidence level through a confidence factor. This invention can realize dynamic monitoring and early warning of the entire process of icing on transmission lines.

This invention discloses a method for locating and imaging local micro-defects based on nonlinear ultrasonic guided wave mixing, belonging to the field of nondestructive testing technology. The method includes: screening guided wave modes on the material under test; exciting two fundamental frequency guided wave signals to form a mixing region in the material; measuring the propagation velocity of the fundamental frequency guided waves and calculating the mixing point position; adjusting the excitation delay to achieve mixing point movement and region scanning; acquiring signals and performing frequency domain analysis to extract the nonlinear mixing signal; and then performing defect determination and imaging. This invention utilizes the high sensitivity of nonlinear ultrasonic guided wave mixing to micro-damage, achieving precise location and imaging of early-stage micro-defects in materials, thus solving the problem of insufficient identification capability of traditional nondestructive testing methods for minute damage.