A new method based on ultrasonic guided wave inspection and matching pursuit for evaluating the axial severity of pipeline defect

Ultrasonic guided wave is in routine use of the nondestructive testing fields as an advanced technique. However, in guided wave based pipeline inspection, the accurate evaluation of the severity of defect is always a challenging task. That is, although the reflection signal in principle includes substantial defect information related to severity and other features of the defect, it is usually rather difficult to be interpreted because of the complexities of reflection process. To carry out the planned maintenance on defective pipelines accurately and efficiently, the ability of evaluating defect severity for pipeline inspection is very important in practical application of guided waves technique, particularly for the cases in which defects exist in the parts of pipeline where their accesses are difficult. In this paper, we propose a method based on matching pursuit for quantifying the severity of pipeline defect along axial direction. The optimized dictionary through introducing prior-knowledge about reflection components is constructed for interactive process of matching pursuit to efficiently decompose the required edge reflection components from defect reflection signal. The axial extent of defect can be then quantitatively evaluated by using obtained information. The experimental results are used to demonstrate the effectiveness of the proposed method.