3D inversion of time-domain electromagnetic data using finite elements and a triple mesh formulation
3D inversion of time-domain electromagnetic data using finite elements and a triple mesh formulation
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使用有限元和三重网格公式对时域电磁数据进行 3D 反演
DOI：
10.1190/geo2020-0079.1
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发表时间：
2021-03
期刊：
影响因子：
3.3
通讯作者：
Auken Esben
中科院分区：
文献类型：
--
作者：
Zhang Bo;Engebretsen Kim Wann;Fi;aca Gianluca;Cai Hongzhu;Auken Esben
在过去的几十年里，人们对三维电磁场反演算法进行了大量的研究。由于三维时间域电磁（TEM）反演算法的计算复杂性和存储要求，许多真实世界的调查是在一维内反演。为了加快计算速度和管理内存的TEM数据的三维反演，我们已经开发了一种方法，使用三个解耦的网格：反演网格，正演模型网格，雅可比计算网格。反演网格是粗糙的规则和结构化网格，使得在模型参数之间容易地实施约束。前向响应在密集的非结构化网格上计算以获得准确的电磁场，而雅可比矩阵在粗糙的非结构化网格上计算。我们发现，使用粗糙网格的雅可比矩阵是足够的反演收敛，同样重要的是，它提供了一个显着的速度提升，在整个反演过程中，相比计算它的前向建模网格。非结构网格采用四面体单元，电磁场采用有限元法计算。反演优化使用标准的高斯-牛顿公式。为了进一步加快速度和内存优化的反演，我们使用区域分解分别计算每个发射机的响应和并行化的问题域使用OpenMP。与一维解相比，密集网格的雅可比矩阵的精度为1%-5%，粗网格的精度为2%-7%，但粗网格的计算时间大约快五倍。我们还研究了一个小的地面TEM数据集在一个地区，三维地球扭曲的电磁场到这样一个程度，一维反演是不可行的算法。
Over several decades, much research has been done to develop 3D electromagnetic inversion algorithms. Due to the computational complexity and the memory requirements for 3D time-domain electromagnetic (TEM) inversion algorithms, many real-world surveys are inverted within one dimension. To speed up calculations and manage memory for 3D inversions of TEM data, we have developed an approach using three uncoupled meshes: an inversion mesh, a forward-model mesh, and a mesh for Jacobian calculations. The inversion mesh is a coarse regular and structured mesh, such that constraints are easily enforced between the model parameters. Forward responses are calculated on a dense unstructured mesh to obtain accurate electromagnetic fields, whereas the Jacobian is calculated on a coarse unstructured mesh. We found that using a coarse mesh for the Jacobian is sufficient for the inversion to converge and, equally important, that it provides a significant speed boost in the overall inversion process, compared to calculating it on the forward-modeling mesh. The unstructured meshes are made of tetrahedral elements, and the electromagnetic fields are calculated using the finite-element method. The inversion optimization uses a standard Gauss-Newton formulation. For further speed up and memory optimizing of the inversion, we use domain decomposition for calculating the responses for each transmitter separately and parallelize the problem over domains using OpenMP. Compared to a 1D solution, the accuracy for the Jacobian is 1%–5% for the dense mesh and 2%–7% for the coarse mesh, but the calculation time is approximately five times faster for the coarse mesh. We also examined the algorithm on a small ground-based TEM data set acquired in an area where a 3D earth distorts the electromagnetic fields to such a degree that a 1D inversion is not feasible.
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影响因子：
2
作者：
K. Noh;Yonghyun Chung;S. Seol;J. Byun;T. Uchida
通讯作者：
K. Noh;Yonghyun Chung;S. Seol;J. Byun;T. Uchida
影响因子：
3.3
作者：
Dikun Yang;D. Oldenburg
通讯作者：
Dikun Yang;D. Oldenburg
一种面向目标的自适应三维分散机载电磁法建模有限元方法
影响因子：
3.3
作者：
Changchun Yin;Bo Zhang;Yunhe Liu;Jing Cai
通讯作者：
Jing Cai
影响因子：
3.3
作者：
D. Oldenburg;E. Haber;R. Shekhtman
通讯作者：
D. Oldenburg;E. Haber;R. Shekhtman
DOI：
10.1109/hicss.1995.375461
发表时间：
1995-01
期刊：
Proceedings of the Twenty-Eighth Annual Hawaii International Conference on System Sciences
影响因子：
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作者：
通讯作者：
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