Abstract A novel fast and accurate algorithm is developed for large‐scale 3‐D gravity magnetic modeling problems. An unstructured grid discretization used to approximate sources with arbitrary mass magnetization distributions. adaptive multilevel multipole (AMFM) method reduce the time. observation octree constructed on a set of arbitrarily distributed sites, while source tetrahedral grid. characteristic independence between octree, which simplifies implementation different survey...

A new adaptive finite-element method for solving 3D direct-current resistivity modeling problems is presented. The begins with an initial coarse mesh, which then adaptively refined wherever a gradient-recovery-based posteriori error estimator indicates that refinement necessary. Then the problem solved again on grid. alternating solution and steps continue until given criterion satisfied. demonstrated two synthetic models known analytical solutions, so errors can be quantified. applicability...

SUMMARY The fast and accurate 3-D magnetotelluric (MT) forward modelling is core engine of the interpretation inversion MT data. In this study, we develop an improved extrapolation cascadic multigrid method (EXCMG) to solve large sparse complex linear system arising from finite-element (FE) discretization on non-uniform orthogonal grids Maxwell’s equations using potentials. First, vector Helmholtz equation scalar auxiliary are derived Coulomb-gauged weighted residual adopted discretize weak...

Abstract We present a multi‐resolution finite‐element approach for three‐dimensional (3D) electromagnetic (EM) induction modeling in spherical Earth. First, the secondary electric field is employed so that both magnetospheric and ionospheric current sources are naturally considered. Second, tetrahedral grids used to approximate heterogeneous crust mantle, local ocean effects at coastal island observatories can be accurately simulated. Furthermore, parallel goal‐oriented hp‐adaptive method...

A new singularity-free analytical formula has been developed for the gravity field of arbitrary 3D polyhedral mass bodies with horizontally and vertically varying density contrast using third-order polynomial functions. First, observation sites are moved to origin coordinate system. Then, volume surface integral theorems invoked successively transform integrals into over polygonal faces line edges bodies. Furthermore, closed-form solutions derived these edges. Thus, can be located inside,...

Although accurate numerical solvers for 3-D direct current (DC) isotropic resistivity models are available even complicated with topography, reliable the anisotropic case still an open question. This study aims to develop a novel and optimal solver accurately calculating DC potentials arbitrary conductivity structures in Earth. First, secondary potential boundary value problem is derived by considering topography conductivity. Then, two posteriori error estimators one using gradient-recovery...

During the last 20 years, geophysicists have developed great interest in using gravity gradient tensor signals to study bodies of anomalous density Earth. Deriving exact solutions has become a dominating task exploration geophysics or geodetic fields. In this study, we compact and simple framework derive measurements for polyhedral bodies, which contrast is represented by general polynomial function. The mass can continuously vary both horizontal vertical directions. our framework, original...

Magnetic object localization techniques have significant applications in automated surveillance and security systems, such as aviation aircrafts or underwater vehicles. In this letter, a practical algorithm was presented to determine the center coordinates magnetic moments of multiple objects using combination field vector its gradient tensor data. It formulates into nonlinear problem, which solved by Levenberg–Marquardt algorithm. The regularization parameters problem were adaptively varied...

SUMMARY To effectively and efficiently interpret or invert controlled-source electromagnetic (CSEM) data which are recorded in areas with the kind of complex geological environments arbitrary topography that typical, 3-D CSEM forward modelling software can quickly solve large-scale problems, provide accurate responses for geo-electrical models be easily incorporated into inversion algorithms required. We have developed a parallel goal-oriented adaptive mesh refinement finite-element approach...

SUMMARY Joint inversion of magnetotelluric (MT) and geomagnetic depth sounding (GDS) responses can constrain the crustal mantle conductivity structures. Previous studies typically use either deterministic algorithms that provide limited information on model uncertainties or using stochastic with a predetermined number layers is generally not known priori. Here, we present new open-source Bayesian framework for joint MT GDS to probe 1D layered Earth’s Within this framework, be accurately...

We present a novel accurate and efficient goal-oriented adaptive finite-element method solution for complex multi-electrodes resistivity system with arbitrary smooth surface topographies. A simple Green's function of half-space model is adopted to eliminate the singularity. unified boundary value problem regular potential formulated so that it shares common matrix. In addition, error estimation technique developed generate an optimal grid highly solutions are obtained minimum computation...

Abstract We develop a novel gravity inversion algorithm in spherical coordinates based on adaptive mesh refinement and multiphysical parameter constraints. The is discretized into tesseroids (spherical prisms) to take the curvature of Earth account. To reduce number unknowns computational cost, adaptively refined according spatial variation parameters at each iteration. Wavelet compression used further requirement. Besides, alleviate nonuniqueness inversion, capable incorporating priori...

We present a novel algorithm to locate multiple underwater objects in real time using gravity field vector and gradient tensor signals. This formulates the task of localization into regularized nonlinear problem, which is solved with standard Levenberg-Marquardt algorithm. The regularization parameters are estimated by cross validation. initial coordinates masses these automatically determined solving single-object problem. A synthetic navigation model two was adopted validate proposed...

The conventional magnetotelluric inversion method is subject to the influence of initial model, which leads an unstable process and a tendency get trapped at local optimal solutions. In contrast, deep learning technology relies on its powerful non-linear fitting capability can construct complex mappings directly from observation data (input) model (output). recent years, it has received extensive attention researchers. Due difficulties in creating sufficiently large dataset performing neural...

Subsidence of the earth’s surface induced by mining activities has always been a critical concern in relevant research fields. This subsidence disrupts original geological structures and can lead to secondary hazards, environmental degradation, threats human lives property. An in-depth investigation this issue led us using three-dimensional finite-difference numerical simulation software FLAC3D 6.0 study. The focuses on Prang Copper Mine area Yunnan Province, China, with particular emphasis...

We present general closed-form solutions for the vertical gravitational anomaly caused by a polyhedral prism with mass density contrast varying depth. Our equations are first ones to implement polynomial of arbitrary order. Singularities in gravity field which arise when observation site is close or anomalous removed our analytic expressions. Therefore, can be located outside, on faces inside bodies. A simple prismatic body adopted test accuracy newly developed solution. Cases constant,...