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Journal articles on the topic 'Guided wave tomography'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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1

Huthwaite, Peter, and Francesco Simonetti. "High-resolution guided wave tomography." Wave Motion 50, no. 5 (2013): 979–93. http://dx.doi.org/10.1016/j.wavemoti.2013.04.004.

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2

Huthwaite, P. "Guided wave tomography with an improved scattering model." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2195 (2016): 20160643. http://dx.doi.org/10.1098/rspa.2016.0643.

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Producing accurate thickness maps of corrosion damage is of great importance for assessing life in the petrochemical industry. Guided wave tomography provides a solution for this, by sending guided waves through the region of interest, then using tomographic imaging techniques to reconstruct the thickness map, importantly eliminating the need to take measurements at all points across the surface. However, to achieve accurate maps, the imaging algorithm must account for the way in which the guided waves interact with corrosion defects, and the complex scattering which occurs. Traditional approaches have exploited the dispersive nature of guided waves: a velocity map is produced from a dataset, then converted to thickness using the dispersion relationship. However, these relationships are derived for plates of constant thickness, which is not the case in the majority of defects, causing significant inaccuracies to exist in the images. This paper develops a more sophisticated inversion solution which accounts for the full-guided wave scattering, enabling more accurate images with resolution better than a wavelength, compared with two wavelengths previously. This is demonstrated with simulated and experimental data. The speed and stability of the algorithm in the presence of random noise and systematic errors is also demonstrated.

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Brath, Alex J., Francesco Simonetti, Peter B. Nagy, and Geir Instanes. "Guided Wave Tomography of Pipe Bends." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 64, no. 5 (2017): 847–58. http://dx.doi.org/10.1109/tuffc.2017.2683259.

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4

Huthwaite, P. "Evaluation of inversion approaches for guided wave thickness mapping." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2166 (2014): 20140063. http://dx.doi.org/10.1098/rspa.2014.0063.

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Accurate inversion is vital for quantitative imaging, including ultrasonic guided wave tomography, where thickness maps of plate-like structures are reconstructed to quantify corrosion damage. The dispersive properties of guided waves are often exploited to enable thickness maps to be produced from wave speed reconstructions. Ray tomography, diffraction tomography and a hybrid algorithm combining their features were investigated to reconstruct wave speed. Test data produced from simple defects of different sizes using a realistic full elastic guided wave model and the equivalent idealized acoustic model were passed to the imaging algorithms, generating wave speed maps, and, from these, thickness maps. For both datasets, ray tomography exhibited poor resolution. Diffraction tomography performed better, but was limited to shallow, small defects. The hybrid algorithm achieved the best results, giving a resolution around 1.5–2 wavelengths from the realistic test data compared to half wavelength from the idealized case. These results were validated with experimental data, and also extended to a realistic corrosion patch confirming the trends demonstrated with simple defects. The resolution loss with realistic data compared with idealized data indicates the acoustic model cannot accurately capture guided wave scattering and an alternative approach is necessary for better resolution reconstructions.

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5

Zhang, Hai Yan, Jian Bo Yu, and Xian Hua Chen. "An Analysis for Effect Factors of Ultrasonic Guided Wave Tomography in Structural Health Monitoring." Advanced Materials Research 282-283 (July 2011): 574–78. http://dx.doi.org/10.4028/www.scientific.net/amr.282-283.574.

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Localized flaws such as corrosions in petroleum pipelines often cause fragility, impairing integrity and shortening service lifetime of the structures. There has been much interest recently in monitoring the integrity of the pipe structures. Ultrasonic guided waves provide a highly efficient technique for rapid pipe inspection because they can be made to propagate significant distances in pitch-catch configurations. Crosshole tomographic geometry is formed in such pitch-catch configurations when transmits and receivers are respectively laid along two parallel circumferential belts around the pipe. Considering the pipe as an unwrapped plate, we investigate the adapation of the tomographic reconstruction in seismology to the guided wave inspection of a pipe. Various effects such as transducer arrangement, mesh precision, sampling interval and iterative algorithm on tomographic reconstruction are analyzed. The results provide a theoretical basis for quantitative detection of pipeline flaw using guided wave tomography.

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Zhao, Xiang, and Joseph L. Rose. "Ultrasonic guided wave tomography for ice detection." Ultrasonics 67 (April 2016): 212–19. http://dx.doi.org/10.1016/j.ultras.2015.12.005.

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7

Zeng, Liang, Jing Lin, Jiadong Hua, and Wen Shi. "Interference resisting design for guided wave tomography." Smart Materials and Structures 22, no. 5 (2013): 055017. http://dx.doi.org/10.1088/0964-1726/22/5/055017.

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8

Leonard, Kevin R., and Mark K. Hinders. "Guided wave helical ultrasonic tomography of pipes." Journal of the Acoustical Society of America 114, no. 2 (2003): 767–74. http://dx.doi.org/10.1121/1.1593068.

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9

Huthwaite, P. "Improving accuracy through density correction in guided wave tomography." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (2016): 20150832. http://dx.doi.org/10.1098/rspa.2015.0832.

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The accurate quantification of wall loss caused by corrosion is critical to the reliable life estimation of pipes and pressure vessels. Traditional thickness gauging by scanning a probe is slow and requires access to all points on the surface; this is impractical in many cases as corrosion often occurs where access is restricted, such as beneath supports where water collects. Guided wave tomography presents a solution to this; by transmitting guided waves through the region of interest and exploiting their dispersive nature, it is possible to build up a map of thickness. While the best results have been seen when using the fundamental modes A0 and S0 at low frequency, the complex scattering of the waves causes errors within the reconstruction. It is demonstrated that these lead to an underestimate in wall loss for A0 but an overestimate for S0. Further analysis showed that this error was related to density variation, which was proportional to thickness. It was demonstrated how this could be corrected for in the reconstructions, in many cases resulting in the near-elimination of the error across a range of defects, and greatly improving the accuracy of life estimates from guided wave tomography.

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10

Zimmermann, Andreas A. E., Peter Huthwaite, and Brian Pavlakovic. "High-resolution thickness maps of corrosion using SH1 guided wave tomography." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2245 (2021): 20200380. http://dx.doi.org/10.1098/rspa.2020.0380.

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Quantifying corrosion damage is vital for the petrochemical industry, and guided wave tomography can provide thickness maps of such regions by transmitting guided waves through these areas and capturing the scattering information using arrays. The dispersive nature of the guided waves enables a reconstruction of wave velocity to be converted into thickness. However, existing approaches have been shown to be limited in in-plane resolution, significantly short of that required to accurately image a defect target of three times the wall thickness (i.e. 3 T) in each in-plane direction. This is largely due to the long wavelengths of the fundamental modes commonly used, being around 4 T for both A0 and S0 at the typical operation points. In this work, the suitability of the first-order shear-horizontal guided wave mode, SH1, has been investigated to improve the resolution limit. The wavelength at the desired operating point is significantly shorter, enabling an improvement in resolution of around 2.4 times. This is first verified by realistic finite-element simulations and then validated by experimental results, confirming the improved resolution limit can now allow defects of maximum extent 3T-by-3T to be reliably detected and sized, i.e. a long-pursued goal of guided wave tomography has been achieved.

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11

Catchings, Rufus D., Michael J. Rymer та Mark R. Goldman. "San Andreas Fault Exploration Using Refraction Tomography and S-Wave-Type and Fϕ-Mode Guided Waves". Bulletin of the Seismological Society of America 110, № 6 (2020): 3088–102. http://dx.doi.org/10.1785/0120200136.

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ABSTRACT Surface ruptures from the 18 April 1906 M∼7.9 San Francisco earthquake were distributed over an ∼35-meter-wide zone at San Andreas Lake on the San Francisco Peninsula in California (Schussler, 1906). Since ∼1906, the surface ruptures have been largely covered by water, but with water levels at near-historic low levels in 2008–2011, we observed that the 1906 surface ruptures were no longer visible. As a fault imaging test, we acquired refraction tomography and guided-wave data across the 1906 surface ruptures in 2011. We found that individual fault traces, as mapped by Schussler (1906), can be identified on the basis of discrete low-velocity zones (VS and VP, reduced ∼40% and ∼34%, respectively) and high-amplitude guided waves. Guided waves have traditionally been observed as large-amplitude waveforms over wide (hundreds of meters to kilometers) zones of faulting, but we demonstrate that by evaluating guided waves (including Rayleigh/Love- and P/SV-types) in terms of peak ground velocity (PGV), individual near-surface fault traces within a fault zone can be precisely located, even more than 100 yr after the surface ruptures. Such precise exploration can be used to focus paleoseismic trenching efforts and to identify or exclude faulting at specific sites. We evaluated PGV of both S-wave-type and Fϕ-mode-type guided waves and found that both wave types can be used to identify subsurface fault traces. At San Andreas Lake (main fault), S-wave-type guided waves travel up to 18% slower than S body waves, and Fϕ-mode guided waves travel ∼60% slower than P body waves but ∼15% faster than S body waves. We found that guided-wave amplitudes vary with frequency but are up to five times higher than those of body waves, including the S wave. Our data are consistent with the concept that guided waves can be a strong-shaking hazard during large-magnitude earthquakes.

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12

Zhang, Hai Yan, Jian Bo Yu, and Xian Hua Chen. "Guided Waves Tomography and Image Fusion for Damage Identification in Pipes." Applied Mechanics and Materials 94-96 (September 2011): 1585–89. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.1585.

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The detection of localized defects such as cracks and corrosion in pipes using guided waves has been shown to be an effective nondestructive evaluation technique for structural health monitoring (SHM). Cross borehole tomography in seismology is introduced into the guided wave inspection of a pipe when the pipe is considered as an unwrapped plate. Guided waves propagating in pipe with a crack defect are simulated using the finite element model and the arrival times for the fastest modes are extracted and sent to the tomographic algorithm. The tomographic reconstruction is based on the simultaneous iterative reconstruction technique (SIRT). For some cylindrical shell geometries such as stacked storage tanks, access to the entire circumference of the structure could be impractical or even impossible, three different image fusion techniques are used to enhance the image equality reconstructed from the incomplete datasets. The results show that the defect is more pronounced after imaging fusion.

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13

Rao, Jing, Madis Ratassepp, and Zheng Fan. "Guided Wave Tomography Based on Full Waveform Inversion." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 63, no. 5 (2016): 737–45. http://dx.doi.org/10.1109/tuffc.2016.2536144.

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14

Huthwaite, Peter, Michael J. Lowe, and Peter Cawley. "Reconstructing complex thickness variations with guided wave tomography." Journal of the Acoustical Society of America 138, no. 3 (2015): 1767. http://dx.doi.org/10.1121/1.4933586.

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15

Belanger, Pierre, Peter Cawley, and Francesco Simonetti. "Guided wave diffraction tomography within the born approximation." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 57, no. 6 (2010): 1405–18. http://dx.doi.org/10.1109/tuffc.2010.1559.

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Druet, Tom, Arnaud Recoquillay, Bastien Chapuis, and Emmanuel Moulin. "Passive guided wave tomography for structural health monitoring." Journal of the Acoustical Society of America 146, no. 4 (2019): 2395–403. http://dx.doi.org/10.1121/1.5128332.

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17

Hua, Jia Dong, Liang Zeng, Jing Lin, and Wen Shi. "Ultrasonic Guided Wave Tomography for Damage Detection in Harsh Environment." Key Engineering Materials 569-570 (July 2013): 1005–12. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.1005.

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Guided wave tomography is an attractive tool for the detection and monitoring of the critical area in a structure. Using signal difference coefficient (SDC) as the tomographic feature, RAPID (Reconstruction Algorithm for the Probabilistic Inspection of Damage) is an effective and flexible tomography algorithm. In this algorithm, signal changes are exclusively attributed to the structural variation. However, external environment factors like water loading or oil loading also change signals significantly. The presence of anti-symmetric mode with a predominant out of plane displacement makes it very sensitive to these interferences and leads to false alarms. In this paper, Lamb wave is excited in the low-frequency domain, where only the fundamental modes A0 and S0 exist. The significant difference in group velocity between the two modes makes it possible to separate them in time domain. A new method is proposed to extract pure S0 mode signal as valid measurement data to improve the algorithm in addressing false alarm caused by water loading. The results of the experiment demonstrate that the improved algorithm has the capability of providing accurate identification of damage in the presence of water loading.

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18

Asokkumar, Aadhik, Elena Jasiūnienė, Renaldas Raišutis, and Rymantas Jonas Kažys. "Comparison of Ultrasonic Non-Contact Air-Coupled Techniques for Characterization of Impact-Type Defects in Pultruded GFRP Composites." Materials 14, no. 5 (2021): 1058. http://dx.doi.org/10.3390/ma14051058.

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This article compares different air-coupled ultrasonic testing methods to characterize impact-type defects in a pultruded quasi-isotropic glass fiber-reinforced plastic (GFRP) composite plate. Using the air-coupled transducers, comparisons among three methods were performed, namely, bulk-wave through transmission, single-side access using guided waves, and ultrasonic-guided wave tomography. The air coupled through transmission technique can determine the size and shape of impact-type defects with a higher resolution, but with the consequence of time consumption and, more importantly, the necessity of access to both sides of the sample. The guided wave technique on the other hand, allows a single-side inspection and is relatively fast. It can be used to determine the size of the defect using ultrasonic B-scan, but the exact shape of the defect will be compromised. Thus, in this article, to determine the shape of the defect, application of the parallel beam tomographic reconstruction technique using guided Lamb waves is demonstrated. Furthermore, a numerical finite element simulation was performed to study the effects of guided wave propagation in the composite sample and interaction with the internal defect. Lastly, the results from the experiments of different techniques were compared according to possibilities of defect sizing and determination of its shape.

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19

Belanger, Pierre, and Peter Cawley. "Feasibility of low frequency straight-ray guided wave tomography." NDT & E International 42, no. 2 (2009): 113–19. http://dx.doi.org/10.1016/j.ndteint.2008.10.006.

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20

Druet, Tom, Jean-Loup Tastet, Bastien Chapuis, and Emmanuel Moulin. "Autocalibration method for guided wave tomography with undersampled data." Wave Motion 89 (June 2019): 265–83. http://dx.doi.org/10.1016/j.wavemoti.2019.04.002.

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Zhang, Hai Yan, Jian Bo Yu, and Xian Hua Chen. "Guided Wave Tomography Using Simultaneous Iterative Reconstruction Technique Improved by Genetic Algorithm." Applied Mechanics and Materials 94-96 (September 2011): 1607–10. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.1607.

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Guided wave tomography has shown great potential for quantitative nondestructive evaluation in structural health monitoring. An improved simultaneous iterative reconstruction technique (SIRT) combining genetic algorithm (GA) is presented in order to improve image quality of guided wave tomography. The simulated reconstructed images of flawed plate and pipe using usual SIRT and improved SIRT methods have been compared quantitatively and qualitatively.

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22

Ernst, Fabian E., Gérard C. Herman, and Auke Ditzel. "Removal of scattered guided waves from seismic data." GEOPHYSICS 67, no. 4 (2002): 1240–48. http://dx.doi.org/10.1190/1.1500386.

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Near‐surface scattered waves form a major source of coherent noise in seismic land data. Most current methods for removing these waves do not attenuate them adequately if they come from other than the inline direction. We present a wave‐theory‐based method for removing (scattered) guided waves by a prediction‐and‐removal algorithm. We assume that the near surface consists of a laterally varying medium, in which heterogeneities are embedded that act as scatterers. We first estimate the dispersive and laterally varying phase slowness field by applying a phase‐based tomography algorithm on the direct groundroll wave. Subsequently, the near‐surface heterogeneities are imaged using a least‐squares criterium. Finally, the scattered guided waves are modeled and subtracted adaptively from the seismic data. We have applied this method to seismic land data and found that near‐surface scattering effects are attenuated.

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23

Li, Dan, Ming Shi, Feng Xu, Chengcheng Liu, Jianqiu Zhang, and Dean Ta. "A New Approach to Guided Wave Ray Tomography for Temperature-Robust Damage Detection Using Piezoelectric Sensors." Sensors 18, no. 10 (2018): 3518. http://dx.doi.org/10.3390/s18103518.

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In this paper, a new approach to guided wave ray tomography for temperature-robust damage detection with time-of-flight (TOF) temperature compensation is developed. Based on the linear relationship between the TOF of a guided wave and temperature, analyses show that the TOF of the baseline signal can be compensated by the temperature measurement of the inspected materials without estimating the temperature compensation parameters. The inversion is based on the optimization of the TOF misfit function between the inspected and compensated baseline TOFs of the guided waves, and is applied by the elastic net penalty approach to perform thickness change mapping in a structural health monitoring (SHM) application. Experiments that are conducted in isotropic plates by piezoelectric sensors demonstrate the effectiveness of the proposed method. According to the results, our approach not only eliminates the artefacts that are caused by a temperature variation from 25 °C to 70 °C but also provides more accurate and clearer imaging of damage than conventional ray tomography methods.

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Willey, C. L., F. Simonetti, P. B. Nagy, and G. Instanes. "Guided wave tomography of pipes with high-order helical modes." NDT & E International 65 (July 2014): 8–21. http://dx.doi.org/10.1016/j.ndteint.2014.03.010.

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He, Jiaze, Daniel C. Rocha, and Paul Sava. "Guided wave tomography based on least-squares reverse-time migration." Structural Health Monitoring 19, no. 4 (2019): 1237–49. http://dx.doi.org/10.1177/1475921719880296.

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A key to successful damage diagnostics and quantification is damage imaging through ultrasonic guided wave tomography. We propose the implementation of least-squares reverse-time migration in a circular array for damage imaging in an aluminum plate. The theory of least-squares reverse-time migration is formulated for guided wave applications along with the summary of an efficient optimization algorithm: the conjugate gradient method. Numerical simulation and laboratory experiments are used to evaluate its performance with a circular array setup. In order to improve the data processing efficiency, the concept of using a limited number of actuators but a relatively large number of sensors is tested. Studies are conducted on three numerical cases, including a rectangular-shaped damage site, a complex-shaped damage site, and six other damage sites varying in size. As an inversion-based method, least-squares reverse-time migration shows significantly improved shape reconstruction with the amplitude quantification capability, compared to conventional reverse-time migration. Our experimental data are generated by piezoelectric wafers as actuators, measured by a scanning laser Doppler vibrometer to form a circular array on an aluminum plate, with a rectangular notch located in the inner region of the array. The damage images using experimental data show consistency in both the simulations using Born scattering and in altered material properties in the damaged region. According to the comparison, least-squares reverse-time migration for guided wave tomography is a promising technology to provide high-resolution large area damage imaging for plate-like structures.

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Gao, Yu, and Jian Qiu Zhang. "A Sparse Model of Guided Wave Tomography for Corrosion Mapping in Structure Health Monitoring Applications." Applied Sciences 9, no. 15 (2019): 3126. http://dx.doi.org/10.3390/app9153126.

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To improve the reconstruction image spatial resolutions of ultrasonic guided wave ray tomography, a sparse model, based on the differences between the inspected and original slowness of the ultrasonic guided waves propagating in the plate-like or pipe-like materials, is first proposed in this paper. Unlike the conventional ultrasonic guided wave tomography whose reconstruction image resolutions are limited by an underdetermined linear model, analyses show that our new model, although it is also underdetermined, can give the optimal solution of the reconstruction image when the constraints on the sparsity of the slowness difference distribution are valid. The reason for the validation of the sparse constraints on the corrosions of the materials is explained. Based on our new model, a least absolute shrinkage and selection operator (LASSO) approach to do the thickness change mapping of a structure health monitoring (SHM) application is then formulated. Analyses also show that the visible artifacts can be avoided using our method, and the spatial resolutions of reconstruction image by our approach can further be improved by increasing the number of grids in the calculation. The approach is validated by experimental work on an aluminum plate. It is also shown that compared to the conventional ray tomography, the presented method can achieve a relatively high spatial resolution, with good suppression of artifacts.

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Lee, Yonghee, and Younho Cho. "An Investigation on a Quantitative Tomographic SHM Technique for a Containment Liner Plate in a Nuclear Power Plant with Guided Wave Mode Selection." Sensors 19, no. 12 (2019): 2819. http://dx.doi.org/10.3390/s19122819.

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The containment liner plate (CLP) in a nuclear power plant is the most critical part of the structure of a power plant, as it prevents the radioactive contamination of the surrounding area. This paper presents feasibility of structural health monitoring (SHM) and an elastic wave tomography method based on ultrasonic guided waves (GW), for evaluating the integrity of CLP. It aims to check the integrity for a dynamic response to a damaged isotropic structure. The proposed SHM technique relies on sensors and, therefore, it can be placed on the structure permanently and can monitor either passively or actively. For applying this method, a suitable guided wave mode tuning is required to verify wave propagation. A finite element analysis (FEA) is performed to figure out the suitable GW mode for a CLP by considering geometric and material condition. Furthermore, elastic wave tomography technique is modified to evaluate the CLP condition and its visualization. A modified reconstruction algorithm for the probabilistic inspection of damage tomography algorithm is used to quantify corrosion defects in the CLP. The location and shape of the wall-thinning defects are successfully obtained by using elastic GW based SHM. Making full use of verified GW mode to Omni-directional transducer, it can be expected to improve utilization of the SHM based evaluation technique for CLP.

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Ratassepp, M., J. Rao, and Z. Fan. "Quantitative imaging of Young's modulus in plates using guided wave tomography." NDT & E International 94 (March 2018): 22–30. http://dx.doi.org/10.1016/j.ndteint.2017.09.016.

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29

Rao, Jing, Madis Ratassepp, and Zheng Fan. "Limited-view ultrasonic guided wave tomography using an adaptive regularization method." Journal of Applied Physics 120, no. 19 (2016): 194902. http://dx.doi.org/10.1063/1.4967790.

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Yang, Di, Xuefeng Shang, Alison Malcolm, Michael Fehler, and Hyoungsu Baek. "Image registration guided wavefield tomography for shear-wave velocity model building." GEOPHYSICS 80, no. 3 (2015): U35—U46. http://dx.doi.org/10.1190/geo2014-0360.1.

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31

Zhao, Chengwei, Sunia Tanweer, Jian Li, Min Lin, Xiang Zhang, and Yang Liu. "Nonlinear Guided Wave Tomography for Detection and Evaluation of Early-Life Material Degradation in Plates." Sensors 21, no. 16 (2021): 5498. http://dx.doi.org/10.3390/s21165498.

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In this paper, the possibility of using nonlinear ultrasonic guided waves for early-life material degradation in metal plates is investigated through both computational modeling and study. The analysis of the second harmonics of Lamb waves in a free boundary aluminum plate, and the internal resonance conditions between the Lamb wave primary modes and the second harmonics are investigated. Subsequently, Murnaghan’s hyperelastic model is implemented in a finite element (FE) analysis to study the response of aluminum plates subjected to a 60 kHz Hanning-windowed tone burst. Different stages of material degradation are reflected as the changes in the third order elastic constants (TOECs) of the Murnaghan’s model. The reconstructed degradations match the actual ones well across various degrees of degradation. The effects of several relevant factors on the accuracy of reconstructions are also discussed.

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Vayavur, Rajesh, and Andrew J. Calvert. "Mitigation of guided wave contamination in waveform tomography of marine seismic reflection data from southwestern Alaska." GEOPHYSICS 81, no. 4 (2016): B101—B118. http://dx.doi.org/10.1190/geo2015-0372.1.

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We have applied 2D frequency-domain acoustic waveform tomography to two different sections of a marine seismic reflection line from southwest Alaska: one section with a deep igneous basement overlain by a thick pile of sediments and the other section with a shallow basement and a thin sedimentary cover. We have evaluated the appearance of dispersive guided waves on both sections, and we have determined that with appropriate data preconditioning it is possible to invert the data using 2D acoustic waveform tomography. Where the basement is deep, we first reduced the dispersive wave contamination of the seismic field data by trace editing, band-pass filtering, and careful choice of the data window for inversion. We then tested different objective functions and inversion scheduling before selecting an approach based on the logarithmic phase, which could be followed by joint phase and amplitude inversion. Where the basement is shallow, the starting model itself, which was generated by ray-based first-arrival tomography, generated acoustic guided waves, necessitating the use of an absorbing boundary condition at the free surface. Logarithmic phase inversion was used, but the amplitude inversion did not converge. To invert seismic data from both sections, we used a layer stripping strategy in which the gradient was used at each stage of the inversion process to check the corresponding model updates. Our results were validated by comparison between synthetic and observed waveforms, comparison of residual phase error plots for the initial and final velocity models, and comparison of waveform tomography velocity models with migrated images. Waveform tomography permits interpretation of the subsurface close to the seafloor where reflection images are contaminated by water-layer multiples, and we inferred the existence of a fault zone from a low-velocity anomaly within the igneous basement.

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Li, Weibin, and Younho Cho. "Imaging wall thinning defect by electromagnetic ultrasonic shear horizontal guided wave tomography." International Journal of Applied Electromagnetics and Mechanics 52, no. 1-2 (2016): 323–30. http://dx.doi.org/10.3233/jae-162033.

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34

Mazeika, Liudas, Rymantas Kazys, Renaldas Raisutis, and Reimondas Sliteris. "Ultrasonic guided wave tomography for the inspection of the fuel tanks floor." International Journal of Materials and Product Technology 41, no. 1/2/3/4 (2011): 128. http://dx.doi.org/10.1504/ijmpt.2011.040291.

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35

Li, Vladimir, Antoine Guitton, Ilya Tsvankin, and Tariq Alkhalifah. "Image-domain wavefield tomography for VTI media." GEOPHYSICS 84, no. 2 (2019): C119—C128. http://dx.doi.org/10.1190/geo2018-0397.1.

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Processing algorithms for transversely isotropic (TI) media are widely used in depth imaging and typically bring substantial improvements in reflector focusing and positioning. Here, we develop acoustic image-domain tomography (IDT) for reconstructing VTI (TI with a vertical symmetry axis) models from P-wave reflection data. The modeling operator yields an integral wave-equation solution, which is based on a separable dispersion relation and contains only P-waves. The zero-dip NMO velocity ([Formula: see text]) and anellipticity parameter [Formula: see text] are updated by focusing energy in space-lag images obtained by least-squares reverse-time migration (LSRTM). Application of LSRTM helps mitigate aperture- and illumination-induced artifacts in space-lag gathers and improve the robustness of [Formula: see text]-estimation. The impact of the trade-off between [Formula: see text] and [Formula: see text] is reduced by a three-stage inversion algorithm that gradually relaxes the constraints on the spatial variation of [Formula: see text]. Assuming that the depth profile of the Thomsen parameter [Formula: see text] is known at two or more borehole locations, we employ image-guided interpolation to constrain the depth scale of the parameter fields and of the migrated image. Image-guided smoothing is also applied to the IDT gradients to facilitate convergence towards geologically plausible models. The algorithm is tested on synthetic reflection and borehole data from the structurally complicated elastic VTI Marmousi-II model. Although the initial velocity field is purely isotropic and substantially distorted, all three relevant parameters ([Formula: see text], [Formula: see text], and [Formula: see text]) are estimated with sufficient accuracy. The algorithm is also applied to a line from a 3D ocean-bottom-node data set acquired in the Gulf of Mexico.

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Li, Weibin, and Younho Cho. "Combination of nonlinear ultrasonics and guided wave tomography for imaging the micro-defects." Ultrasonics 65 (February 2016): 87–95. http://dx.doi.org/10.1016/j.ultras.2015.10.016.

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Huthwaite, P., R. Ribichini, P. Cawley, and M. J. S. Lowe. "Mode selection for corrosion detection in pipes and vessels via guided wave tomography." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 60, no. 6 (2013): 1165–77. http://dx.doi.org/10.1109/tuffc.2013.2679.

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Huthwaite, Peter, and Matthias Seher. "Robust helical path separation for thickness mapping of pipes by guided wave tomography." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 62, no. 5 (2015): 927–38. http://dx.doi.org/10.1109/tuffc.2014.006884.

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Rao, Jing, Madis Ratassepp, and Zheng Fan. "Investigation of the reconstruction accuracy of guided wave tomography using full waveform inversion." Journal of Sound and Vibration 400 (July 2017): 317–28. http://dx.doi.org/10.1016/j.jsv.2017.04.017.

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Tsai, Meng-Tsan, Wen-Ju Chen, Ting-Yen Tsai, Hsiang-Chieh Lee, Chun-Chieh Wang, and Ya-Ju Lee. "Optical Coherence Tomography/Angiography-Guided Tumor Ablation With a Continuous-Wave Laser Diode." IEEE Access 8 (2020): 43191–99. http://dx.doi.org/10.1109/access.2020.2976557.

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Abbaszadeh, Javad, Herlina Abdul Rahim, Ruzairi Abdul Rahim, and Sahar Sarafi. "Ultrasonic Tomography System: Optimizing the Frequency in a Metal Pipe Conveyor." Applied Mechanics and Materials 284-287 (January 2013): 572–76. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.572.

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Ultrasonic Tomography has a dominant role in industry to generate cross sectional images of any object. In this paper, method of designing an Ultrasonic Tomography System due to the propagation manner of ultrasonic wave inside the various materials is investigated. The correct method of mounting of Ultrasonic sensors and behavior of the ultrasonic wave propagation in different layers has been simulated by the use of finite element software (COMSOL Multiphysics 3.5). To increase in practical nondestructive evaluation and inspection, we should increase our understanding of the basic physics and wave mechanics associated with guided wave inspection. A suitable ultrasonic sensor base on its efficiency and satisfying the simulation criteria is found and practically implemented on the surface of metal pipe. it is done by estimating the resonance frequency of sensor due to manner of ultrasonic wave propagation in different frequencies shown in simulation results. The proposed optimum frequency for the applied sensors is 40 kHz in which is tested practically and experimental results prove the high efficiency of this system.

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Barros, Sámia Valéria dos Santos, Niro Higuchi, Claudete Catanhede do Nascimento, Roberto Daniel de Araújo, and Prof Dr Flávio de São Pedro Filho. "Wave Propagation Technology in Non-destructive assays for Wood Qualifying in Tropical Amazon." International Journal for Innovation Education and Research 7, no. 8 (2019): 259–74. http://dx.doi.org/10.31686/ijier.vol7.iss8.1673.

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Non-destructive tests use techniques which allow a body to be evaluated without changing its physical, mechanical and dimensional features and without compromising its future use. Impulse tomography analysis is a non-destructive method which allows a piece of wood to be analyzed by passing mechanical waves through it, allowing researchers to evaluate its qualities in advance and detect the presence of defects. This research reports the assessment of the efficiency of impulse tomography as a technique for identifying defects and the in situ evaluation of tree wood from Amazonian timber species. The data were collected at INPA's Tropical Forestry Experimental Station (ZF-2), located at BR 174, Manaus/AM, in a plot 1 (one) hectare in size, where 7 species were chosen at random. For evaluation, the ARBOTOM pulse tomograph at DAP (diameter at breast height) was used to rapidly capture cross sectional images of the wood. Next, the trees were cut to evaluate cross sections of the wood by eye and samples were taken to determine the density of the wood. The results enabled researchers to detect the presence of distinct zones in the wood by varying the mechanical wave speed indicated by various colour zones revealed in the X-ray. These colour differences are attributable to variations in density related to the different wood substances in the tree. It was found that the wood density and mechanical wave velocity correlated with R² 0.647. The dynamic elastic modulus of the species studied was satisfactory, showing a good degree of resistance. Impulse tomography technique provides complete information and can assist forest managers to make a decision about tree felling that is guided by the assessment of the internal quality of the wood.

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Li, Jing, Kai Lu, Sherif Hanafy, and Gerard Schuster. "Two robust imaging methodologies for challenging environments: Wave-equation dispersion inversion of surface waves and guided waves and supervirtual interferometry + tomography for far-offset refractions." Interpretation 6, no. 4 (2018): SM27—SM37. http://dx.doi.org/10.1190/int-2017-0229.1.

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Two robust imaging technologies are reviewed that provide subsurface geologic information in challenging environments. The first one is wave-equation dispersion (WD) inversion of surface waves and guided waves (GW) for the shear-velocity (S-wave) and compressional-velocity (P-wave) models, respectively. The other method is traveltime inversion for the velocity model, in which supervirtual refraction interferometry (SVI) is used to enhance the signal-to-noise ratio of far-offset refractions. We have determined the benefits and liabilities of both methods with synthetic seismograms and field data. The benefits of WD are that (1) there is no layered-medium assumption, as there is in conventional inversion of dispersion curves. This means that 2D or 3D velocity models can be accurately estimated from data recorded by seismic surveys over rugged topography, and (2) WD mostly avoids getting stuck in local minima. The liability is that WD for surface waves is almost as expensive as full-waveform inversion (FWI) and, for Rayleigh waves, only recovers the S-velocity distribution to a depth no deeper than approximately 1/2 to 1/3 wavelength of the lowest-frequency surface wave. The limitation for GW is that, for now, it can estimate the P-velocity model by inverting the dispersion curves from GW propagating in near-surface low-velocity zones. Also, WD often requires user intervention to pick reliable dispersion curves. For SVI, the offset of usable refractions can be more than doubled, so that traveltime tomography can be used to estimate a much deeper model of the P-velocity distribution. This can provide a more effective starting velocity model for FWI. The liability is that SVI assumes head-wave first arrivals, not those from strong diving waves.

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Brath, Alex J., Francesco Simonetti, Peter B. Nagy, and Geir Instanes. "Experimental Validation of a Fast Forward Model for Guided Wave Tomography of Pipe Elbows." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 64, no. 5 (2017): 859–71. http://dx.doi.org/10.1109/tuffc.2017.2683264.

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Rao, Jing, Madis Ratassepp, and Zheng Fan. "Quantification of thickness loss in a liquid-loaded plate using ultrasonic guided wave tomography." Smart Materials and Structures 26, no. 12 (2017): 125017. http://dx.doi.org/10.1088/1361-665x/aa95e9.

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Pieczonka, Łukasz, Tadeusz Uhl, and Adam Martowicz. "Simulation of Guided Waves Propagation in Axial Transmission Measurements in Human Radius." Applied Mechanics and Materials 9 (October 2007): 127–41. http://dx.doi.org/10.4028/www.scientific.net/amm.9.127.

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This paper is a brief review of the axial transmission measurements methodology. Theoretical background and description of the methodology is presented. Simulations made to verify some of the statements found in the scientific literature about the subject matter are described. Simulation performed were meant to be a basis for specifying parameters of the experimental set up to be used in the future. Three dimensional finite difference code was used to simulate wave propagation in human radius. Two models have been prepared to compare the results. One was an idealized geometry of the diaphysis of human radius and second was a reconstructed anatomical geometry from scans acquired with Computed Tomography (CT). Conclusions about the wave propagation character and feasibility of low frequency measurements in medical diagnostics are discussed.

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Rao, Jing, Madis Ratassepp, Danylo Lisevych, Mahadhir Hamzah Caffoor, and Zheng Fan. "On-Line Corrosion Monitoring of Plate Structures Based on Guided Wave Tomography Using Piezoelectric Sensors." Sensors 17, no. 12 (2017): 2882. http://dx.doi.org/10.3390/s17122882.

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Wei, Zheng, Songling Huang, Shen Wang, and Wei Zhao. "Magnetostriction-Based Omni-Directional Guided Wave Transducer for High-Accuracy Tomography of Steel Plate Defects." IEEE Sensors Journal 15, no. 11 (2015): 6549–58. http://dx.doi.org/10.1109/jsen.2015.2462834.

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Cailly, William, Henri Walaszek, Sébastien Brzuchacz, Fan Zhang, and Philippe Lasaygues. "Low-Frequency Guided Wave Quantitative Reconstruction of Corrosion in Plates, 1D Diffraction Problem." Acta Acustica united with Acustica 105, no. 6 (2019): 970–86. http://dx.doi.org/10.3813/aaa.919378.

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Guided Wave Tomography is a nondestructive imaging technique that consists in inverting guided wave propagation data to localize defects. In particular, this technique should provide quantitative information about the corrosion state of metallic plates by reconstructing a thickness map from diffraction or time-of-flight measurements. In this paper we first present an analytical framework for corrosion profile reconstruction considering the 1D case. Due to the fact that, in practice, the low frequency ultrasound range (typically 50 to 100 kHz) is used for long range inspections, the first-order shear deformation approximation is relevant for plate thicknesses encountered in metallic structures. This leads to an analytical description of guided wave phenomena: diffraction, refraction and mode conversion, for 5 modes: A0, S0, SH0, A1 and SH1. The validity of an analytical approach to modeling thickness loss defects, in particular the validity of the first Born approximation, is discussed by comparing with elastodynamic numerical results. The comparison results show that the nonlinear behavior with depth increase, or width increase, of the defects (distortion) can be fully described using a multimodal high order Born series. Consequently, a consistent iterative inversion Born series based algorithm can be used to deal with the reconstruction of strong thickness losses.

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Yuan, Yanhua O., Ebru Bozdağ, Caio Ciardelli, Fuchun Gao, and F. J. Simons. "The exponentiated phase measurement, and objective-function hybridization for adjoint waveform tomography." Geophysical Journal International 221, no. 2 (2020): 1145–64. http://dx.doi.org/10.1093/gji/ggaa063.

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SUMMARY Seismic tomography has arrived at the threshold of the era of big data. However, how to extract information optimally from every available time-series remains a challenge; one that is directly related to the objective function chosen as a distance metric between observed and synthetic data. Time-domain cross-correlation and frequency-dependent multitaper traveltime measurements are generally tied to window selection algorithms in order to balance the amplitude differences between seismic phases. Even then, such measurements naturally favour the dominant signals within the chosen windows. Hence, it is difficult to select all usable portions of seismograms with any sort of optimality. As a consequence, information ends up being lost, in particular from scattered waves. In contrast, measurements based on instantaneous phase allow extracting information uniformly over the seismic records without requiring their segmentation. And yet, measuring instantaneous phase, like any other phase measurement, is impeded by phase wrapping. In this paper, we address this limitation by using a complex-valued phase representation that we call ‘exponentiated phase’. We demonstrate that the exponentiated phase is a good substitute for instantaneous-phase measurements. To assimilate as much information as possible from every seismogram while tackling the non-linearity of inversion problems, we discuss a flexible hybrid approach to combine various objective functions in adjoint seismic tomography. We focus on those based on the exponentiated phase, to take into account relatively small-magnitude scattered waves; on multitaper measurements of selected surface waves; and on cross-correlation measurements on specific windows to select distinct body-wave arrivals. Guided by synthetic experiments, we discuss how exponentiated-phase, multitaper and cross-correlation measurements, and their hybridization, affect tomographic results. Despite their use of multiple measurements, the computational cost to evaluate gradient kernels for the objective functions is scarcely affected, allowing for issues with data quality and measurement challenges to be simultaneously addressed efficiently.

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