A PCA and ELM Based Adaptive Method for Channel Equalization in MFL Inspection

Magnetic flux leakage (MFL) as an efficient method for pipeline flaw detection plays important role in pipeline safety. This nondestructive test technique assesses the health of the buried pipeline. The signal is gathered by an array of hall-effect sensors disposed at the magnetic neutral plane of a pair of permanent magnet in the pipeline inspection gauge (PIG) clinging to the inner surface of the pipe wall. The magnetic flux measured by the sensors reflects the health condition of the pipe. The signal is influenced by not only the condition of the pipe, but also by the lift-off value of the sensors and various properties of electronic component. The consistency of the position of the sensors is almost never satisfied and each sensor measures differently. In this paper, a new scheme of channel equalization is proposed for MFL signal in order to correct sensor misalignments, which eventually improves accuracy of defect characterization. The algorithm proposed in this paper is adaptive to the effects of error on the disposition of the sensor due to manufacturing imperfections and movements of the sensors. The algorithm is tested by data acquired from an experimental pipeline. The results show the effectiveness of the proposed algorithm

THE VBHF TO STUDY THE WELD-LINE MOVEMENT AND SPRINGBACK OF TAILOR-WELDED BLANKS WITH ARC-WELD-LINE

Based on the tailor-welded blanks with the radius of 180 mm arc-weld-line,and use Dynaform numerical simulation techniques to study TWBs with the transverse arc-weld-line a under the variable blank holder force changing with travel distance or position,The research shows that a certain range of blank-holder force can control the weld-line movement of TWBs and the springback angle of TWBs under the condition of VBHF changing with position.But beyond the change of the blank holder force,it is beneficial to sheet metal forming,not to the control of springback angle.Compared with other methods,V loading method benefits for the control of the weld-line movement and springback control,it has great effect on the forming of welding plate under the condition of VBHF changing with travel distance.Variable blank-holder force control methods,including changing with position and changing with travel distance,allow more thin side in sheet metal forming into the die,and reduce the welding plate deformation of the thin side material,due to easing the tailor-welded plate thickness caused by uneven deformation.Finally,the weld-line movement and the springback angle controlled to improve the forming quality of welding plate