نتایج جستجو برای: sparse inversion

تعداد نتایج: 102863  

2014
Yongliang Bai Simon E. Williams R. Dietmar Müller Zhan Liu Maral Hosseinpour

Crustal thickness is a critical parameter for understanding the processes of continental rifting and breakup and the evolution of petroleum systems within passive margins. However, direct measurements of crustal thickness are sparse and expensive, highlighting the need for methodologies using gravity anomaly data, jointly with other geophysical data, to estimate crustal thickness. We evaluated ...

2016
Lucas Almeida Michael Wakin Paul Sava

Missing trace reconstruction is an ongoing challenge in seismic processing due to incomplete acquisition schemes and irregular grids. Noise is also a concern because it is naturally present in acquired seismic data through several mechanisms such as natural noise and equipment noise. Both problems need to be adequately addressed, especially because they negatively affect several important proce...

Journal: :CoRR 2011
François Orieux Olivier Féron Jean-François Giovannelli

This paper is devoted to the problem of sampling Gaussian fields in high dimension. Solutions exist for two specific structures of inverse covariance : sparse and circulant. The proposed approach is valid in a more general case and especially as it emerges in inverse problems. It relies on a perturbation-optimization principle: adequate stochastic perturbation of a criterion and optimization of...

Journal: :CoRR 2014
Franz J. Király Louis Theran

We propose an algebraic combinatorial method for solving large sparse linear systems of equations locally that is, a method which can compute single evaluations of the signal without computing the whole signal. The method scales only in the sparsity of the system and not in its size, and allows to provide error estimates for any solution method. At the heart of our approach is the so-called reg...

2014
Franz J. Király Louis Theran

We propose an algebraic combinatorial method for solving large sparse linear systems of equations locally that is, a method which can compute single evaluations of the signal without computing the whole signal. The method scales only in the sparsity of the system and not in its size, and allows to provide error estimates for any solution method. At the heart of our approach is the so-called reg...

ژورنال: فیزیک زمین و فضا 2018

In this paper a fast method for large-scale sparse inversion of magnetic data is considered. The L1-norm stabilizer is used to generate models with sharp and distinct interfaces. To deal with the non-linearity introduced by the L1-norm, a model-space iteratively reweighted least squares algorithm is used. The original model matrix is factorized using the Golub-Kahan bidiagonalization that proje...

2008
Sharon M. Gourdji Kim L. Mueller Kevin Schaefer Anna M. Michalak

[1] Geostatistical inverse modeling has been shown to be a viable alternative to synthesis Bayesian methods for estimating global continental-scale CO2 fluxes. This study extends the geostatistical approach to take advantage of spatially and temporally varying auxiliary data sets related to CO2 flux processes, which allow the inversion to capture more grid-scale flux variability and better cons...

Journal: :فیزیک زمین و فضا 0
نوید امینی گروه فیزیک زمین، موسسه ژئوفیزیک دانشگاه تهران عبدالرحیم جواهریان دانشکده مهندسی نفت، دانشگاه صنعتی امیرکبیر، تهران

seismic tomography is an imaging technique which creates maps of subsurface elastic properties such as p/s wave velocity, density and attenuation, based on observed seismograms and use of sophisticated inversion algorithms. amongst different acquisition geometries, seismic cross-hole tomography has a special position in geophysical surveys with many applications in hydrocarbons, coal and other ...

2012
Felix Lucka

Sparsity has become a key concept for solving of high-dimensional inverse problems using variational regularization techniques. Recently, using similar sparsity-constraints in the Bayesian framework for inverse problems by encoding them in the prior distribution has attracted attention. Important questions about the relation between regularization theory and Bayesian inference still need to be ...

Journal: :Inverse Problems 2021

Data-driven reduced order models (ROMs) are combined with the Lippmann-Schwinger integral equation to produce a direct nonlinear inversion method. The ROM is viewed as Galerkin projection and sparse due Lanczos orthogonalization. Embedding into continuous problem, data-driven internal solution produced. This then used in equation, thus making further iterative updates unnecessary. We show numer...

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