Abstract Full waveform inversion is an effective tool for recovering the properties of Earth from seismograms. However, it suffers local minima caused mainly by limited accuracy starting model and lack a low-frequency component in seismic data. Because high velocity contrast between salt sediment, relation perturbation strongly nonlinear. Therefore, can easily get trapped minima. Since nearly constant, we make most this characteristic with total variation regularization to mitigate In paper,...

Abstract Full-waveform inversion (FWI) is a powerful tool to reconstruct subsurface geophysical parameters with high resolution. As 3D surveys become widely implemented, corresponding processing techniques are required solve complex geological cases, while large amount of computation the most challenging problem. We propose an adaptive variable-grid FWI on graphics unit devices improve computational efficiency without losing accuracy. The irregular-grid discretization strategy based...

Seismic forward modeling in tilted transverse isotropic (TTI) media is crucial for the application of reverse time migration and full-waveform inversion. Modeling based on conventional coupled pseudoacoustic wave equations not only generates SV-wave artifacts, but it also suffers from instabilities which anisotropy parameter [Formula: see text]. To address these issues, we have started with exact vertical transversely phase velocity formula developed novel pure qP- qSV-wave governing TTI by...

In finite-difference (FD) method, numerical dispersion is the dominant factor influencing accuracy of seismic modelling. Various optimized FD schemes for scalar wave modelling have been proposed to reduce grid dispersion, while time–space domain elastic not fully investigated yet. this paper, an scheme with Equivalent Staggered Grid (ESG) has developed. We start from constant P- and S-wave speed equations then deduce analytical plane solutions in wavenumber eigenvalue decomposition method....

SUMMARY Recently, we have developed a localized adaptive waveform inversion (LAWI) method to tackle the cycle-skipping issue in velocity reconstruction through seismic inversion. The LAWI employs local matching filter, computed using Gabor deconvolution, measure instantaneous time-shift between observed and calculated data. Unlike (AWI) approach, can take non-stationarity data into account. In this work, investigate two types of regularization based on prior information about expected which...

Polarity reversal in converted wave images of elastic reverse time migration destructs the reflection events after stacking multi-shot profile. We derive a new imaging method for reverse-time to automatically circumvent polarity reversal. Instead obtaining scalar P-wave and vector S-wave potentials from wavefield by using Helmholtz decomposition as conventional methods, we obtain P- displacement wavefields based on decoupled equation, which denotes component along propagation direction...

SUMMARY Correctly interpreting phase events thanks to data processing techniques based on correlation or deconvolution has been the focus of numerous studies in field high-resolution seismic imaging using full-waveform inversion. To mitigate non-convexity misfit function and risk converge towards non-informative local minima, make it possible information instead amplitude design more convex function, alleviating dependency inversion process accuracy initial models. Such however rely...

Least-squares reverse time migration (LSRTM), an effective tool for imaging the structures of earth from seismograms, can be characterized as a linearized waveform inversion problem. We have investigated performance three minimization functionals [Formula: see text] norm, hybrid and Wasserstein metric ([Formula: metric) LSRTM. The used in this study is based on dynamic formulation transport problems, primal-dual gradient algorithm introduced to efficiently compute between two seismograms....

To exploit Hessian information in full-waveform inversion (FWI), the matrix-free truncated Newton method can be used. In such a method, Hessian-vector product computation is one of major concerns due to huge memory requirements and demanding computational cost. Using adjoint-state estimated by zero-lag crosscorrelation first-/second-order incident wavefields second-/first-order adjoint wavefields. Different from implementation frequency-domain FWI, construction time domain becomes much more...

This study is a preliminary analysis of the causes upwarping reinforced concrete slabs twin-block slab track, specifically on subgrade–bridge transition section. The considers structural features and force characteristics track basis site investigations numerical simulation, corresponding repair method proposed. It determined that temperature gradient slab, connection status between hydraulically bonded layer (HBL), position terminal spine are main factors lead to slab. Model tests...

Equivalent staggered-grid (ESG) as a new family of schemes has been utilized in seismic modeling, imaging, and inversion. Traditionally, the Taylor series expansion is often applied to calculate finite-difference (FD) coefficients on spatial derivatives, but simulation results suffer serious numerical dispersion large frequency zone. We develop an optimized equivalent (OESG) FD method that can simultaneously suppress temporal for solving second-order system 3D elastic wave equation. On one...

Regularization is a central topic in the study of solutions ill-posed inverse problems. High-resolution seismic imaging using full-waveform inversion (FWI) belongs to this category through anisotropic diffusion, technique that emerged field image processing, an interesting alternative conventional regularization strategies. Exploiting structural information given image, it has capability smooth along its main structures. The difficulty how design diffusion operator. concept coherence...

The genetic algorithm is the intelligence computational method widely used in solving optimization problems, however many current algorithms has premature convergence and stagnation behavior while complex question. This may because had lost ability of discovering that new or potential material before limited its search to solution space with wide range. Enlightened by hierarchical fair competition existed nature, this paper studied a model based on Pyramid which uses pipeline structure...

Summary We introduce a fast numerical method to compute earth mover’s distance for full waveform inversion. The based on gradient flow formulation of two positive signals can be recast as an L1 type convex optimization problem and primal-dual is applied solve this problem. For signed seismic data, we effective strategy decompose data into part negative part, then recombine the new apply them Numerical examples have demonstrated that our mitigate local minima in

This paper is based on the application of automobile ECU remote update in order to facilitate automotive update.At first, related technology Bootloader was introduced.System design project completed according requirement.Then "incremental update" put forwarded as a way program update.The carried out detailed design, which including memory layout, state flow chart, specific software running processes and structures.Finally, results experiment prove that more safety faster than traditional method.

Ferroelectric relaxor behavior of Ba0.92-xCa0.08Ndx(Zr0.18Ti0.815Y0.0025Mn0.0025)O3 (x = 0, 0.5%, 1.0% and 2.0% mol) ceramics has been investigated. All the compositions have only tetragonal perovskite structure at room temperature. The dielectric peak constant samples decrease broaden, temperature (Tm ) shifts toward lower as content Nd increases. Diffuse phase transition (DPT) strong frequency dispersion can be observed. When varied from 0 to mol, degree deviation Curie-Weiss law (△Tm is...

Estimation of an attenuation parameter, represented by the quality factor Q, holds paramount importance in seismic exploration. One main challenges Q estimation through viscoacoustic full-waveform inversion (FWI) is effectively decoupling from velocity. In this study, our objective to enhance addressing critical aspects, such as gradient preconditioning, workflow, and misfit design. By developing a new preconditioner that approximates diagonal Hessian, we facilitate automatic parameter...