ELECTROMAGNETIC IMAGING OF UNDERGROUND TARGETS USING CONSTRAINED OPTIMIZATION
ELECTROMAGNETIC IMAGING OF UNDERGROUND TARGETS USING CONSTRAINED OPTIMIZATION
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DOI：
10.1109/36.387572
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发表时间：
1995-05-01
影响因子：
8.2
通讯作者：
PLUMB, RG
中科院分区：
文献类型：
--
作者：
CHATURVEDI, P;PLUMB, RG
近年来，几种高频电磁技术已被用于探测和识别地下物体。为了获得高质量的地下目标图像，许多技术都需要对采集的数据进行后处理。通过将成像问题转化为电磁散射逆问题，可以获得目标本构参数的精确重建。本文采用频域Born迭代法重建浅目标的图像，Born迭代法要求在每一步迭代中先求解前向散射问题，再求解逆散射问题，前向散射问题采用时域有限差分法（FDTD）求解，逆散射问题采用约束优化法求解。本文用FDTD方法对埋在地下的几个典型目标进行了二维模拟计算，用同样的FDTD程序计算了求解约束最优化问题所需的绿色函数，用有耗非均匀地面模型进行了几次模拟，以说明这种方法在实际情况中的应用。反演过程可以用于重建图像的许多现实的介电对比度，其中线性玻恩近似失败。此外，它也表明，少量的测量结果在准确的重建与这种技术，使用多个频率也进行了研究。
Several high-frequency electromagnetic techniques have been used in recent years to detect and identify buried objects. Post-processing of the collected data is performed in many of these techniques to obtain high-quality images of buried targets, Accurate reconstructions of the target's constitutive parameters can be obtained by casting the imaging problem in terms of an inverse electromagnetic scattering problem, A number of techniques have been put forth recently to invert the electromagnetic data to obtain such images, In this paper, we use a frequency-domain Born iterative method to reconstruct images of shallow targets, The Born iterative technique requires successive solutions to a forward scattering problem followed by an inverse scattering problem at each iteration step, We use a finite-difference time domain (FDTD) algorithm to solve the forward scattering problem and constrained optimization for the inverse problem. Two-dimensional simulated data for several canonical objects buried in the ground are obtained using the FDTD technique, The same FDTD code is also used in calculating the Green's function required for solving the constrained optimization problem, Lossy, inhomogeneous ground models are used in several simulations to illustrate the use of this technique for practical situations, The inversion process can be used to reconstruct images for many realistic dielectric contrasts for which a linear Born approximation fails. Moreover, it is also shown that a small number of measurements results in accurate reconstructions with this technique, Use of multiple frequencies is also investigated.