基于磁梯度张量的地下小目标相关成像方法

Correlation Imaging Method of Small Subsurface Target Based on Magnetic Gradient Tensor

针对小目标铁磁物质反演方法研究中,磁总场探测包含信息不完整并且传统反演方法无法通过先验信息与目标建立联系的问题,提出了基于磁梯度张量的地下小目标相关成像方法。该方法首先利用有限元方法对铁磁目标在测量面的磁梯度张量场进行正演计算以作为实测数据;然后将地下待成像空间划分为三维规则网格并将每个网格节点等效为磁偶极子,计算每个磁偶极子在测量面产生的磁梯度张量数据与实测数据的互相关系数,作为磁偶极子在待成像空间的密度分布图;最后利用迭代计算将密度分布图转化为实际的物性参数分布图。仿真验证表明:该方法不仅能够获得地下小目标的分布情况,还能得到目标位于不同位置的实际物性参数值。

The total magnetic field detection anomaly include a single exception message and can not establish contact with the target through prior information in the inversion study of small ferromagnetic material target.A correlation imaging method based on magnetic gradient tensor data was put forward in this paper.Firstly,forward modeling data was obtained by using finite element method as measured magnetic gradient tensor data of ferromagnetic target.Then the subsurface space was divided into a 3Dregular grid and each grid node was equivalent to a magnetic dipole.The cross correlation was calculated between the magnetic gradient tensor at the measurement surface and the observed data.The resultant correlation coefficients was used to describe equivalent magnetic dipole distribution in a probability sense.Finally,an iterative method was proposed to finish the transformation from probability value to actual physical parameter distribution.Theoretical analysis showed that this method could not only obtain the distribution of the small subsurface target,but also get the actual material parameter at different location.