混凝土缺陷检测的电阻成像约束反问题算法优化

电阻层析成像(ERT,electrical resistance tomography)是一种以对象内部电导率分布为成像目标的可视化技术,具有低成本、无损伤等优点,在混凝土缺陷检测领域具有广阔的应用前景。根据电阻成像基本原理,基于Matlab平台编制ERT正问题和反问题程序,实现了约束牛顿迭代算法(NCRM,Newton’s constrained reconstruction method)。计算过程中,根据混凝土基体及缺陷的电学特性和基体与缺陷的锐化边界条件对算法施加约束,通过逐步修正初值来干预逆运算,从而提高ERT反问题的计算稳定性和重构图像质量。试验结果表明:针对混凝土材料的缺陷检测,提出的ERT约束算法用较少的迭代次数即获得较好的效果,能较大程度消除成像目标的伪影,提高锐度,实现对混凝土缺陷相对精准的无损检测。

Research on resistance imaging constraint inverse problem in concrete defect detection

Electrical Resistance Tomography (ERT) is a kind of medical imaging technology taking the body''s conductivity distribution as the target.With the advantages of visualization, low cost and no damage, it has broad prospects in the field of concrete defect detection. Based on the basic principle of resistance imaging, the MATLAB platform is used to compile the ERT forward and the inverse problem program. According to the electrical characteristics of concrete matrix and defects, we apply constraints to the algorithm and interfere with Newton-Raphson iteration process in inverse operation by modifying initial values, so as to improve the computational stability and image resolution of ERT posed inverse problem. The results show that the ERT constraint algorithm can reduce the number of iterations and eliminate imaging artifacts to a large extent, thus improving acuity and realizing relatively accurate nondestructive detection of concrete defects.