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Extraction of effective response for controlled-source electromagnetic data based on clustering analysis 认领 引用
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作者 Cong Zhou Zhan-zi Qin +2 位作者 Liang Yang Tara P.Banjade Xiao-fei Zhou 《Applied Geophysics》 SCIE CSCD 2025年第4期1297-1312,1499,共16页
The issue of strong noise has increasingly become a bottleneck restricting the precision and application space of electromagnetic exploration methods.Noise suppression and extraction of effective electromagnetic respo... The issue of strong noise has increasingly become a bottleneck restricting the precision and application space of electromagnetic exploration methods.Noise suppression and extraction of effective electromagnetic response information under a strong noise background is a crucial scientific task to be addressed.To solve the noise suppression problem of the controlled-source electromagnetic method in strong interference areas,we propose an approach based on complex-plane 2D k-means clustering for data processing.Based on the stability of the controlled-source signal response,clustering analysis is applied to classify the spectra of different sources and noises in multiple time segments.By identifying the power spectra with controlled-source characteristics,it helps to improve the quality of the controlled-source response extraction.This paper presents the principle and workflow of the proposed algorithm,and demonstrates feasibility and effectiveness of the new algorithm through synthetic and real data examples.The results show that,compared with the conventional Robust denoising method,the clustering algorithm has a stronger suppression effect on common noise,can identify high-quality signals,and improve the preprocessing data quality of the controlledsource electromagnetic method. 展开更多
关键词 controlled-source electromagnetic method Data processing Cluster analysis Noise
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Controlled-source electromagnetic data denoising based on improved vision transformer 认领 引用
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作者 Xiao Guo-zhen Li Guang +2 位作者 Zhang Kun Wang Xin Li-Jin 《Applied Geophysics》 SCIE CSCD 2025年第4期1058-1077,1494,共20页
Controlled-source electromagnetic method(CSEM)has been widely applied in engineering and environmental surveys,resource and energy exploration,as well as geological disaster detection.However,due to the increasingly h... Controlled-source electromagnetic method(CSEM)has been widely applied in engineering and environmental surveys,resource and energy exploration,as well as geological disaster detection.However,due to the increasingly human noises,CSEM data are inevitably subjected to electromagnetic noise,which severely affect the detection results.To address this issue,we propose an improved vision transformer(IVIT)deep learning denoising network to suppress cultural noise,and use wide-field electromagnetic(WFEM,a kind of CSEM)data as an example to validate the effectiveness and superiority.First,typical high-quality CSEM data are selected and a series of simulated noises are added to create a sample library.Second,the well-prepared sample library is used to train the IVIT network.Finally,the well-trained model is employed to perform a one-step denoising operation on the noisy CSEM data to obtain high-quality data.Comparative experiments are conducted with denoising convolutional neural network(DnCNN),residual networks(ResNet),residual DnCNN(ResDnCNN),ResDnCNN combined with shift-invariant sparse coding(ResDnCNN-SISC),U-Net networks,and long short-term memory networks(LSTM).The proposed method effectively removes white noise,pulse noise,and square wave noise,and improves the signal-to-noise ratio(SNR)by approximately 20 dB.Compared with the competitive methods,it has obvious advantages.Analysis of CSEM data from Sichuan Province,China,shows that the data processed by the proposed method results in smoother apparent resistivity curves.In summary,the proposed denoising method can be used to suppress the strong noise of CSEM data,which is helpful for subsequent research of inversion. 展开更多
关键词 Controlled-source electromagnetic method(CSEM) signal denoising visual transformer(VIT) deep learning
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Controlled-source electromagnetic data processing based on gray system theory and robust estimation 认领 引用 被引量：15
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作者 Mo Dan Jiang Qi-Yun +3 位作者 Li Di-Quan Chen Chao-Jian Zhang Bi-Ming and Liu Jia-Wen 《Applied Geophysics》 SCIE CSCD 2017年第4期570-580,622,共11页
We propose a novel method that combines gray system theory and robust M-estimation method to suppress the interference in controlled-source electromagnetic data. We estimate the standard deviation of the data using a ... We propose a novel method that combines gray system theory and robust M-estimation method to suppress the interference in controlled-source electromagnetic data. We estimate the standard deviation of the data using a gray model because of the weak dependence of the gray system on data distribution and size. We combine the proposed and threshold method to identify and eliminate outliers. Robust M-estimation is applied to suppress the effect of the outliers and improve the accuracy. We treat the M-estimators of the preserved data as the true data. We use our method to reject the outliers in simulated signals containing noise to verify the feasibility of our proposed method. The processed values are observed to be approximate to the expected values with high accuracy. The maximum relative error is 3.6676%, whereas the minimum is 0.0251%. In processing field data, we observe that the proposed method eliminates outliers, minimizes the root-mean-square error, and improves the reliability of controlled-source electromagnetic data in follow-up processing and interpretation. 展开更多
关键词 Controlled-source electromagnetic method gray system theory robust M-estimates
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2.5D forward modeling and inversion of frequency-domain airborne electromagnetic data 认领 引用 被引量：4
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作者 李文奔 曾昭发 +3 位作者 李静 陈雄 王坤 夏昭 《Applied Geophysics》 SCIE CSCD 2016年第1期37-47,218,共11页
Frequency-domain airborne electromagnetics is a proven geophysical exploration method.Presently,the interpretation is mainly based on resistivity-depth imaging and onedimensional layered inversion;nevertheless,it is d... Frequency-domain airborne electromagnetics is a proven geophysical exploration method.Presently,the interpretation is mainly based on resistivity-depth imaging and onedimensional layered inversion;nevertheless,it is difficult to obtain satisfactory results for two- or three-dimensional complex earth structures using 1D methods.3D forward modeling and inversion can be used but are hampered by computational limitations because of the large number of data.Thus,we developed a 2.5D frequency-domain airborne electromagnetic forward modeling and inversion algorithm.To eliminate the source singularities in the numerical simulations,we split the fields into primary and secondary fields.The primary fields are calculated using homogeneous or layered models with analytical solutions,and the secondary（scattered） fields are solved by the finite-element method.The linear system of equations is solved by using the large-scale sparse matrix parallel direct solver,which greatly improves the computational efficiency.The inversion algorithm was based on damping leastsquares and singular value decomposition and combined the pseudo forward modeling and reciprocity principle to compute the Jacobian matrix.Synthetic and field data were used to test the effectiveness of the proposed method. 展开更多
关键词 Frequency-domain airborne electromagnetic finite element method 2.5D geoelectric model damped least-squares method
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Precision of meshfree methods and application to forward modeling of two-dimensional electromagnetic sources 认领 引用 被引量：4
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作者 李俊杰 严家斌 皇祥宇 《Applied Geophysics》 SCIE CSCD 2015年第4期503-515,627,共13页
Meshfree method offers high accuracy and computational capability and constructs the shape function without relying on predefined elements. We comparatively analyze the global weak form meshfree methods, such as eleme... Meshfree method offers high accuracy and computational capability and constructs the shape function without relying on predefined elements. We comparatively analyze the global weak form meshfree methods, such as element-free Galerkin method （EFGM）, the point interpolation method （PIM）, and the radial point interpolation method （RPIM）. Taking two dimensional Poisson equation as an example, we discuss the support-domain dimensionless size, the field nodes, and background element settings with respect to their effect on calculation accuracy of the meshfree method. RPIM and EFGM are applied to controlled- source two-dimensional electromagnetic modeling with fixed shape parameters. The accuracy of boundary conditions imposed directly and by a penalty function are discussed in the case of forward modeling of two-dimensional magnetotellurics in a homogeneous medium model. The coupling algorithm of EFG-PIM and EFG-RPIM are generated by integrating the PIM or RPIM and EFGM. The results of the numerical modeling suggest the following. First, the proposed meshfree method and corresponding coupled methods are well-suited for electromagnetic numerical modeling. The accuracy of the algorithm is the highest when the support-domain dimensionless size is 1.0 and the distribution of field nodes is consistent with the nodes of background elements. Second, the accuracy of PIM and RPIM are lower than that of EFGM for the Poisson equation but higher than EFGM for the homogeneous medium MT response. Third, RPIM overcomes the matrix inversion problem of PIM and has a wider selection of support-domain dimensionless sizes as compared to RPIM. 展开更多
关键词 Element-free Galerkin method point-interpolation method radial pointinterpolation method Poisson equation controlled-source electromagnetic modeling coupled meshfree method
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New methods of controlled-source electromagnetic detection in China 认领 引用 被引量：47
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作者 Qingyun DI Guoqiang XUE +1 位作者 Changchun YIN Xiu LI 《Science China Earth Sciences》 SCIE EI CAS CSCD 2020年第9期1268-1277,共10页
As an important branch of geophysical exploration method,the electromagnetic method with artificial source has advanced rapidly in the past decade.These methods are classified as airborne electromagnetic method,ground... As an important branch of geophysical exploration method,the electromagnetic method with artificial source has advanced rapidly in the past decade.These methods are classified as airborne electromagnetic method,ground-air electromagnetic method,ground electromagnetic method,and marine electromagnetic method.Over the years,researchers in China have made significant improvement to the fundamental theory,forward modeling and inverse for series of electromagnetic detection methods.Conversely,significant progress was made in the development of corresponding equipment.The researched techniques and their developed equipment have been successfully utilized to detect underground targets as deep as 10 km.However,there is increasing need for deep resources exploration,urban subsurface study,and prediction,monitoring and detection of geological hazards.To meet the increasing need and catch up with the advanced international level of exploration technologies and developed equipment,there is urgent necessity and requirement to continue developing geophysical methods and the corresponding equipment. 展开更多
关键词 Controlled-source Electromagnetic method Multiscale Deep earth detection
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Three-dimensional land FD-CSEM forward modeling using edge finite-element method 认领 引用 被引量：5
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作者 LIU Jian-xin LIU Peng-mao TONG Xiao-zhong 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第1期131-140,共10页
A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys,based on a finite-element discretization of the Helmholtz equation for the electric fields,has been deve... A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys,based on a finite-element discretization of the Helmholtz equation for the electric fields,has been developed.The main difference between our modeling method and those previous works is edge finite-element approach applied to solving the three-dimensional land frequency-domain electromagnetic responses generated by horizontal electric dipole source.Firstly,the edge finite-element equation is formulated through the Galerkin method based on Helmholtz equation of the electric fields.Secondly,in order to check the validity of the modeling code,the numerical results are compared with the analytical solutions for a homogeneous half-space model.Finally,other three models are simulated with three-dimensional electromagnetic responses.The results indicate that the method can be applied for solving three-dimensional electromagnetic responses.The algorithm has been demonstrated,which can be effective to modeling the complex geo-electrical structures.This efficient algorithm will help to study the distribution laws of3-D land frequency-domain controlled-source electromagnetic responses and to setup basis for research of three-dimensional inversion. 展开更多
关键词 three-dimensional model frequency-domain electromagnetic method horizontal electric dipole forward modeling edge finite-element
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