Pulsed eddy current thermography (PECT) and eddy current lock-in thermography (ECLIT) are non-destructive testing (NDT) techniques of high promising and interest in subsurface defect detection. In the previous researches, the induction coil was set above the defect region and it always parallel tothe defect orientation. However, the location and orientation of subsurface defects cannot be determined before detection. Therefore, the scanning induction thermography (SIT) based on dynamic thermography is proposed by some researchers to localize and distinguish the subsurface defects. Still, the main challenges of SIT are how to detect the subsurface defect orientation and quantify the depth. So that, the quantitative analysis in SIT with the new feature extraction methods was investigated and improved to detect the subsurface defect orientation and quantify the defect depth within 5 mm by using experimental studies.

中文翻译：

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扫描感应热成像技术用于地下缺陷取向检测和深度量化

脉冲涡流热成像技术（PECT）和涡流锁定热成像技术（ECLIT）是非破坏性测试（NDT）技术，在地下缺陷检测领域具有很高的应用前景。在先前的研究中，感应线圈设置在缺陷区域上方，并且始终平行于缺陷方向。但是，在检测之前无法确定表面缺陷的位置和方向。因此，一些研究人员提出了基于动态热成像的扫描感应热成像（SIT）来定位和区分表面缺陷。尽管如此，SIT的主要挑战还是如何检测地下缺陷的方向并量化深度。以便，