Non-destructive Testing Method Of Pipeline Based On Pulsed Eddy Current Technology

This paper focuses on the defect signal extraction and defect edge imaging in pulsed eddy current nondestructive testing systems.It lays the foundation for the accurate detection of the defect position imaging in the metal oil pipeline by pulsed eddy current non-destructive testing.Since the noise in the air,lift-off of the probe,and air layer will affect the collected response signal when the pulsed eddy current system detects the metal pipe,the existing feature value extraction method will be affected by the environment and cannot be accurately measured.The location of the defect,so this paper proposes a method based on the combination of Fisher discriminant and system identification analysis,which can improve the reliability of defect parameter identification.Firstly,the transfer function model H(s)of the system is established by the response signal,and the characteristics of the response signal are reflected by the parameters of the transfer function model.Then Fisher's discriminant analysis(FDA)is used to extract the important characteristic quantities of the response signal from the parameters.Finally,the important feature quantities are classified by the maximum value selection procedure to find the feature quantity that represents the defect signal.In this paper,a new method based on improved ant colony algorithm is proposed to detect the defect edge detection,and the technique of pulsed eddy current scanning imaging is presented.The improvement of ant colony algorithm includes two points: the first one is improved the two-time pheromone matrix updating formula.In the pheromone matrix update formula,the pheromone difference value i,j(35)? is added between two pixels.The second improvement is to improve the heuristic information formula by selecting the difference(35)I of adjacent pixels as the independent variable in the function,the improved ant colony algorithm can increase the probability of the ant taking the optimal path and improve the accuracy and efficiency of calculation.After the pulsed Eddy current scanning imaging,an improved ant colony algorithm is used to extract the edge of the image,through the analysis of the edge information,the relevant information such as the location of the defect can be analyzed,and then the quantitative evaluation of the information is made.Accurate quantification of the location of defects,so achieve the purpose of defect detection.