The phase transitions of the RCo2 (R=Er, Ho and Dy) compounds are of first-order type and a metam... more The phase transitions of the RCo2 (R=Er, Ho and Dy) compounds are of first-order type and a metamagnetic transition is observed above the Curie temperature. Owing to their large magnetic entropy change, the RCo2 compounds are competitive candidates as the working substance for magnetic refrigeration. In this paper we discuss the origin of this large magnetic entropy change.
This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects i... more This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic Lamb waves (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode me...
Due to richness of frequency content and robustness of anti-interference, pulsed eddy current tes... more Due to richness of frequency content and robustness of anti-interference, pulsed eddy current testing of cracks in conductive materials attracts great interests. The objective of this study is to identify the surface and subsurface cracks that probably extends in all directions with pulsed eddy current probe. Based on the principle that cracks crossing the eddy current path with a right angle help PEC probe to gain the highest sensitivity, some probes with improved structures are developed to detect cracks in all directions. First, the structures of probes are described and their detection mechanisms are deduced. Then, experiments are carried out to verify probes’ performance. Comparison and further analysis are also derived with experimental results.
Pulse eddy current (PEC) testing is broadly used as an effective nondestructive testing technique... more Pulse eddy current (PEC) testing is broadly used as an effective nondestructive testing technique especially for the defect detection of multiple layer and irregular surface objects. PEC testing’s adoption of repeated pulses as excitation provides for the penetration of many frequency components into the piece being tested and returns more information from various depths. As the lift-off height will inevitably
Proceedings of the 2nd International Conference of Structural Health Monitoring and Integrity Management (ICSHMIM2014), Nanjing, China, 24-26 September 2014, 2015
Insight - Non-Destructive Testing and Condition Monitoring, 2014
ABSTRACT In this paper, we propose a dynamic taboo search procedure to reconstruct the three-dime... more ABSTRACT In this paper, we propose a dynamic taboo search procedure to reconstruct the three-dimensional (3D) defect profile from magnetic flux leakage (MFL) signals in pipeline inspection. Division of the region of interest (ROI) of the pipe wall in the forward model is refined progressively to accelerate the dynamic inversion process using the taboo search algorithm. To demonstrate the efficiency and accuracy of the proposed method, we reconstruct defects from both simulated and actually measured MFL signals. In both cases, the presented dynamic inversion procedure exhibits high inversion speed, while maintaining high prediction accuracy.
2010 International Conference on Measuring Technology and Mechatronics Automation, 2010
In this paper, a new strategy to inspect the slope of steady arm based on computer vision is pres... more In this paper, a new strategy to inspect the slope of steady arm based on computer vision is presented, in light of the present monitoring ways are not more acceptable for their slowness, imprecision, laborious and potentially hazardous. First, the hardware structure of the image acquisition module of the inspection system is introduced; then, the formulas on calculating the steady
To equivalently test the shielding effect of heavy current transformer (HCT) with shielding coils... more To equivalently test the shielding effect of heavy current transformer (HCT) with shielding coils in laboratory, an eccentric bus-bar testing method has been used to simultaneously simulate the effect of the primary bus-bar and adjacent bus-bar since 1970s. But still there hasn't been an effective way to determine the crucial parameters, especially the eccentric distance, which means the distance from the center of the eccentric bus-bar to the center of HCT. This paper presents several analytical formulas to determine the eccentric distance and relevant parameters in the testing method, which may overcome the present difficulty. The formulas are derived from magnetic circuit model, and further verified by finite element method (FEM). Numerical results show that these formulas are effective and easy to use in the testing of HCT. Further more, if the eccentric current, which should be equal to the original primary current, is still too high to reproduce in laboratory, auxiliary and compensating windings could be adopted to reduce it.
The phase transitions of the RCo2 (R=Er, Ho and Dy) compounds are of first-order type and a metam... more The phase transitions of the RCo2 (R=Er, Ho and Dy) compounds are of first-order type and a metamagnetic transition is observed above the Curie temperature. Owing to their large magnetic entropy change, the RCo2 compounds are competitive candidates as the working substance for magnetic refrigeration. In this paper we discuss the origin of this large magnetic entropy change.
This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects i... more This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic Lamb waves (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode me...
Due to richness of frequency content and robustness of anti-interference, pulsed eddy current tes... more Due to richness of frequency content and robustness of anti-interference, pulsed eddy current testing of cracks in conductive materials attracts great interests. The objective of this study is to identify the surface and subsurface cracks that probably extends in all directions with pulsed eddy current probe. Based on the principle that cracks crossing the eddy current path with a right angle help PEC probe to gain the highest sensitivity, some probes with improved structures are developed to detect cracks in all directions. First, the structures of probes are described and their detection mechanisms are deduced. Then, experiments are carried out to verify probes’ performance. Comparison and further analysis are also derived with experimental results.
Pulse eddy current (PEC) testing is broadly used as an effective nondestructive testing technique... more Pulse eddy current (PEC) testing is broadly used as an effective nondestructive testing technique especially for the defect detection of multiple layer and irregular surface objects. PEC testing’s adoption of repeated pulses as excitation provides for the penetration of many frequency components into the piece being tested and returns more information from various depths. As the lift-off height will inevitably
Proceedings of the 2nd International Conference of Structural Health Monitoring and Integrity Management (ICSHMIM2014), Nanjing, China, 24-26 September 2014, 2015
Insight - Non-Destructive Testing and Condition Monitoring, 2014
ABSTRACT In this paper, we propose a dynamic taboo search procedure to reconstruct the three-dime... more ABSTRACT In this paper, we propose a dynamic taboo search procedure to reconstruct the three-dimensional (3D) defect profile from magnetic flux leakage (MFL) signals in pipeline inspection. Division of the region of interest (ROI) of the pipe wall in the forward model is refined progressively to accelerate the dynamic inversion process using the taboo search algorithm. To demonstrate the efficiency and accuracy of the proposed method, we reconstruct defects from both simulated and actually measured MFL signals. In both cases, the presented dynamic inversion procedure exhibits high inversion speed, while maintaining high prediction accuracy.
2010 International Conference on Measuring Technology and Mechatronics Automation, 2010
In this paper, a new strategy to inspect the slope of steady arm based on computer vision is pres... more In this paper, a new strategy to inspect the slope of steady arm based on computer vision is presented, in light of the present monitoring ways are not more acceptable for their slowness, imprecision, laborious and potentially hazardous. First, the hardware structure of the image acquisition module of the inspection system is introduced; then, the formulas on calculating the steady
To equivalently test the shielding effect of heavy current transformer (HCT) with shielding coils... more To equivalently test the shielding effect of heavy current transformer (HCT) with shielding coils in laboratory, an eccentric bus-bar testing method has been used to simultaneously simulate the effect of the primary bus-bar and adjacent bus-bar since 1970s. But still there hasn't been an effective way to determine the crucial parameters, especially the eccentric distance, which means the distance from the center of the eccentric bus-bar to the center of HCT. This paper presents several analytical formulas to determine the eccentric distance and relevant parameters in the testing method, which may overcome the present difficulty. The formulas are derived from magnetic circuit model, and further verified by finite element method (FEM). Numerical results show that these formulas are effective and easy to use in the testing of HCT. Further more, if the eccentric current, which should be equal to the original primary current, is still too high to reproduce in laboratory, auxiliary and compensating windings could be adopted to reduce it.
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Papers by Songling Huang