Small scale adaptation of the seismic full waveform inversion method ‐ Application to civil engineering applications

2008 ◽  
Vol 123 (5) ◽  
pp. 3373-3373 ◽  
Author(s):  
Francois Bretaudeau ◽  
Donatienne Leparoux ◽  
Odile Abraham
Keyword(s):  
Civil Engineering ◽  
Waveform Inversion ◽  
Small Scale ◽  
Inversion Method ◽  
Full Waveform Inversion ◽  
Engineering Applications ◽  
Scale Adaptation ◽  
Full Waveform

Improvement of GPR Full-waveform inversion images using Cone Penetration Test data

Geophysics ◽  
2021 ◽  
pp. 1-74
Author(s):  
Zhen Zhou ◽  
Anja Klotzsche ◽  
Jessica Schmäck ◽  
Harry Vereecken ◽  
Jan van der Kruk
Keyword(s):  
Waveform Inversion ◽  
Cone Penetration Test ◽  
Small Scale ◽  
Inversion Method ◽  
Full Waveform Inversion ◽  
Penetration Test ◽  
Cone Penetration ◽  
Full Waveform ◽  
Effective Source

Detailed characterization of aquifers is critical and challenging due to the existence of heterogeneous small-scale high-contrast layers. For an improved characterization of subsurface hydrological characteristics, crosshole ground penetrating radar (GPR) and Cone Penetration Test (CPT) measurements are performed. In comparison to the CPT approach that can only provide 1D high resolution data along vertical profiles, crosshole GPR enables measuring 2D cross-sections between two boreholes. Generally, a standard inversion method for GPR data is the ray-based approach that considers only a small amount of information and can therefore only provide limited resolution. In the last decade, full-waveform inversion (FWI) of crosshole GPR data in time domain has matured, and provides inversion results with higher resolution by exploiting the full recorded waveform information. However, the FWI results are limited due to complex underground structures and the non-linear nature of the method. A new approach that uses CPT data in the inversion process is applied to enhance the resolution of the final relative permittivity FWI results by updating the effective source wavelet. The updated effective source wavelet possesses a priori CPT information and a larger bandwidth. Using the same starting models, a synthetic model comparison between the conventional and updated FWI results demonstrates that the updated FWI method provides reliable and more consistent structures. To test the method, five experimental GPR cross-section results are analyzed with the standard FWI and the new proposed updated approach. Both synthetic and experimental results indicate the potential of improving the reconstruction of subsurface aquifer structures by combining conventional 2D FWI results and 1D CPT data.

scholarly journals Application of an Improved Ultrasound Full-Waveform Inversion in Bone Quantitative Measurement

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 260
Author(s):  
Meng Suo ◽  
Dong Zhang ◽  
Yan Yang
Keyword(s):  
Nonlinear Equations ◽  
Waveform Inversion ◽  
Optimal Solution ◽  
Inversion Method ◽  
Full Waveform Inversion ◽  
Inversion Algorithm ◽  
Elastic Wave Equation ◽  
Full Waveform ◽  
Ultrasonic Propagation ◽  
Joint Velocity

Inspired by the large number of applications for symmetric nonlinear equations, an improved full waveform inversion algorithm is proposed in this paper in order to quantitatively measure the bone density and realize the early diagnosis of osteoporosis. The isotropic elastic wave equation is used to simulate ultrasonic propagation between bone and soft tissue, and the Gauss–Newton algorithm based on symmetric nonlinear equations is applied to solve the optimal solution in the inversion. In addition, the authors use several strategies including the frequency-grid multiscale method, the envelope inversion and the new joint velocity–density inversion to improve the result of conventional full-waveform inversion method. The effects of various inversion settings are also tested to find a balanced way of keeping good accuracy and high computational efficiency. Numerical inversion experiments showed that the improved full waveform inversion (FWI) method proposed in this paper shows superior inversion results as it can detect small velocity–density changes in bones, and the relative error of the numerical model is within 10%. This method can also avoid interference from small amounts of noise and satisfy the high precision requirements for quantitative ultrasound measurements of bone.

Full-waveform inversion with wavefield gradients

2021 ◽  
Author(s):  
Sneha Singh ◽  
Yann Capdeville ◽  
Heiner Igel ◽  
Navid Hedjazian ◽  
Thomas Bodin
Keyword(s):  
Waveform Inversion ◽  
Effective Model ◽  
Small Scale ◽  
Full Waveform Inversion ◽  
Coupling Tensor ◽  
Full Waveform ◽  
Surface Topographies ◽  
Good For ◽  
Incorrect Model

<p>Wavefield gradient instruments, such as rotational sensors and DAS systems, are becoming more and more accessible in seismology. Their usage for Full Waveform Inversion (FWI) is in sight. Nevertheless, local small-scale heterogeneities, like geological inhomogeneities, surface topographies, and cavities are known to affect wavefield gradients. This effect is in fact measurable with current instruments. For example, the agreement between data and synthetics computed in a tomographic model is often not as good for rotation as it is for displacement.</p><p>The theory of homogenization can help us understand why small-scale heterogeneities strongly affect wavefield gradients, but not the wavefield itself. It tells us that at any receiver measuring wavefield gradient, small-scale heterogeneities cause the wavefield gradient to couple with strain through a coupling tensor <strong>J</strong>. Furthermore, this <strong>J</strong> is 1) independent of source, 2) independent of time, but 3) only dependent on the receiver location. Consequently, we can invert for <strong>J</strong> based on an effective model for which synthetics fit displacement data reasonably well. Once inverted, <strong>J</strong> can be used to correct all other wavefield gradients at that receiver.</p><p>Here, we aim to understand the benefits and drawbacks of wavefield gradient sensors in a FWI context. We show that FWIs performed with rotations and strains are equivalent to that performed with displacements provided that 1) the number of data is sufficient, and 2) the receivers are placed far away from heterogeneities. In the case that receivers are placed near heterogeneities, we find that due to the effect of these heterogeneities, an incorrect model is recovered from inversion. In this case therefore, the coupling tensor <strong>J</strong> needs to be taken into account for each receiver to get rid of the effect.</p>

2D time-domain visco-acoustic full waveform inversion method

2015 ◽  
Author(s):  
Haishan Li* ◽  
Wuyang Yang ◽  
Enli Wang ◽  
Xueshan Yong
Keyword(s):  
Time Domain ◽  
Waveform Inversion ◽  
Inversion Method ◽  
Full Waveform Inversion ◽  
Full Waveform

Characterization of Railway Subgrade Using an Elastic Wave Full-Waveform Inversion Method

2020 ◽  
Vol 23 (4) ◽  
pp. 347-358
Author(s):  
Boyoung Kim ◽  
Jun Won Kang ◽  
Yeong-Tae Choi ◽  
Seung Yup Jang
Keyword(s):  
Elastic Wave ◽  
Waveform Inversion ◽  
Inversion Method ◽  
Full Waveform Inversion ◽  
Full Waveform
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