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Journal articles on the topic 'Synthetic waveform'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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1

Shragge, Jeff. "Waveform inversion by one-way wavefield extrapolation." GEOPHYSICS 72, no. 4 (2007): A47—A50. http://dx.doi.org/10.1190/1.2733622.

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One-way Riemannian wavefield extrapolation (RWE) on computational meshes conforming to the direction of turning-wave propagation is an alternative forward-modeling procedure for waveform inversion. Forward-modeling tests demonstrate that the RWE approach may be a sufficiently accurate approximation for calculating the wavefield phases important for early-arrival waveform inversion. Initial results indicate that RWE waveforms are well matched at wide offsets to finite-difference data, and can be used in a waveform inversion scheme to invert synthetic data for moderate 1D velocity perturbations.

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2

Milenkovic, Paul. "Least Mean Square Measures of Voice Perturbation." Journal of Speech, Language, and Hearing Research 30, no. 4 (1987): 529–38. http://dx.doi.org/10.1044/jshr.3004.529.

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A signal processing technique is described for measuring the jitter, shimmer, and signal-to-noise ratio of sustained vowels. The measures are derived from the least mean square fit of a waveform model to the digitized speech waveform. The speech waveform is digitized at an 8.3 kHz sampling rate, and an interpolation technique is used to improve the temporal resolution of the model fit. The ability of these procedures to measure low levels of perturbation is evaluated both on synthetic speech waveforms and on the speech recorded from subjects with normal voice characteristics.

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Keers, Henk, Lane R. Johnson, and Don W. Vasco. "Acoustic crosswell imaging using asymptotic waveforms." GEOPHYSICS 65, no. 5 (2000): 1569–82. http://dx.doi.org/10.1190/1.1444845.

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Seismic waveforms are inverted using an asymptotic method. The asymptotic method models amplitudes correctly at the caustics and takes nonstationary raypaths into account when computing the waveforms, and thus is an extension of geometrical ray theory. Using numerical differencing, partial derivatives of the data with respect to the model are computed. As expected, these partial derivatives (or sensitivity functions) are concentrated along, but not confined to, raypaths. The sensitivity functions enable the formulation of a waveform inversion algorithm, which is applied to a synthetic crosswel

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Vasco, D. W., Henk Keers, John E. Peterson, and Ernest Majer. "Zeroth‐order asymptotics: Waveform inversion of the lowest degree." GEOPHYSICS 68, no. 2 (2003): 614–28. http://dx.doi.org/10.1190/1.1567231.

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Sensitivity computation is an integral part of many waveform inversion algorithms. An accurate and efficient technique for sensitivity computation follows from the zero‐order asymptotic solution to the elastodynamic equation of motion. Given the particular form of the asymptotic solution, we show that perturbations in high‐frequency waveforms are primarily sensitive to perturbations in phase. The resulting expression for waveform sensitivity is the time derivative of the synthetic seismogram multiplied by the phase sensitivity. All of the necessary elements for a step in the waveform inversion

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Lee, Kee-Woong, and Woo-Kyung Lee. "Waveform diversity for SAR ECCM based on random phase and code rate transition." International Journal of Microwave and Wireless Technologies 9, no. 6 (2017): 1345–54. http://dx.doi.org/10.1017/s1759078717000678.

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In this paper, we propose an effective waveform diversity scheme that can be applicable to synthetic aperture radar (SAR) operations affected by interfering signals. A novel approach is taken to achieve fully adaptive SAR waveform diversity that generates sufficient number of orthogonal signals with modest performance trade-off. To this purpose, multiple phased-code waveforms are arbitrarily generated with mutually low cross-correlations. They exhibit a highly flexible characteristic as their code lengths are not limited and Doppler tolerance is well preserved throughout SAR imaging. Various S

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Sun, Xinhua, Xiaoming Tang, C. H. (Arthur) Cheng, and L. Neil Frazer. "P- and S-wave attenuation logs from monopole sonic data." GEOPHYSICS 65, no. 3 (2000): 755–65. http://dx.doi.org/10.1190/1.1444774.

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In this paper, a modification of an existing method for estimating relative P-wave attenuation is proposed. By generating synthetic waveforms without attenuation, the variation of geometrical spreading related to changes in formation properties with depth can be accounted for. With the modified method, reliable P- and S-wave attenuation logs can be extracted from monopole array acoustic waveform log data. Synthetic tests show that the P- and S-wave attenuation values estimated from synthetic waveforms agree well with their respective model values. In‐situ P- and S-wave attenuation profiles pro

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Chen, Kai, Sheng Jin, and Ming Deng. "Multifunction waveform generator for EM receiver testing." Geoscientific Instrumentation, Methods and Data Systems 7, no. 1 (2018): 11–19. http://dx.doi.org/10.5194/gi-7-11-2018.

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Abstract. In many electromagnetic (EM) methods – such as magnetotelluric, spectral-induced polarization (SIP), time-domain-induced polarization (TDIP), and controlled-source audio magnetotelluric (CSAMT) methods – it is important to evaluate and test the EM receivers during their development stage. To assess the performance of the developed EM receivers, controlled synthetic data that simulate the observed signals in different modes are required. In CSAMT and SIP mode testing, the waveform generator should use the GPS time as the reference for repeating schedule. Based on our testing, the freq

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8

Sinha, Mrinal, and Gerard T. Schuster. "Interferometric full-waveform inversion." GEOPHYSICS 84, no. 1 (2019): R45—R60. http://dx.doi.org/10.1190/geo2018-0047.1.

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Velocity errors in the shallow part of the velocity model can lead to erroneous estimates of the full-waveform inversion (FWI) tomogram. If the location and topography of a reflector are known, then such a reflector can be used as a reference reflector to update the underlying velocity model. Reflections corresponding to this reference reflector are windowed in the data space. Windowed reference reflections are then crosscorrelated with reflections from deeper interfaces, which leads to partial cancellation of static errors caused by the overburden above the reference interface. Interferometri

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Jeon, Se-Yeon, Fabian Glatz, and Michelangelo Villano. "A Waveform-Encoded SAR Implementation Using a Limited Number of Cyclically Shifted Chirps." Remote Sensing 13, no. 15 (2021): 3038. http://dx.doi.org/10.3390/rs13153038.

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Synthetic aperture radar (SAR) provides high-resolution images of the Earth’s surface irrespective of sunlight and weather conditions. In conventional spaceborne SAR, nadir echoes caused by the pulsed operation of SAR may significantly affect the SAR image quality. Therefore, the pulse repetition frequency (PRF) is constrained within the SAR system design to avoid the appearance of nadir echoes in the SAR image. As an alternative, the waveform-encoded SAR concept using a pulse-to-pulse variation of the transmitted waveform and dual-focus postprocessing can be exploited for nadir echo removal a

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Wang, Yichuan, and Igor B. Morozov. "A simple approach to nonstationary source waveform estimation in seismic records." GEOPHYSICS 85, no. 3 (2020): V257—V268. http://dx.doi.org/10.1190/geo2019-0133.1.

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A simple and practical method for source-waveform estimation from reflection seismic records is implemented by iterative identification of locally strongest reflections. Instead of conventional hypotheses about statistical properties of the whole records, the method is based on a general observation that stronger reflection peaks occur relatively sparsely and that smaller peaks adjacent to them are mutually incoherent. Tests with real well logs suggest that the subsurface often possesses such sparseness. Based on this property, the source waveform is obtained from seismic records by optimizing

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11

Romanowicz, Barbara, Li-Wei Chen, and Scott W. French. "Accelerating full waveform inversion via source stacking and cross-correlations." Geophysical Journal International 220, no. 1 (2019): 308–22. http://dx.doi.org/10.1093/gji/ggz437.

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SUMMARY Accurate synthetic seismic wavefields can now be computed in 3-D earth models using the spectral element method (SEM), which helps improve resolution in full waveform global tomography. However, computational costs are still a challenge. These costs can be reduced by implementing a source stacking method, in which multiple earthquake sources are simultaneously triggered in only one teleseismic SEM simulation. One drawback of this approach is the perceived loss of resolution at depth, in particular because high-amplitude fundamental mode surface waves dominate the summed waveforms, with

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Snieder, R., M. Y. Xie, A. Pica, and A. Tarantola. "Retrieving both the impedance contrast and background velocity: A global strategy for the seismic reflection problem." GEOPHYSICS 54, no. 8 (1989): 991–1000. http://dx.doi.org/10.1190/1.1442742.

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Recorded seismic reflection waveforms contain information as to the small‐scale variations of impedance and the large‐scale variations of velocity. This information can be retrieved by minimizing the misfit between the recorded waveforms and synthetic seismograms as a function of the model parameters. Because of the different physical characters of the velocity and the impedance, we update these parameters in an alternating fashion, which amounts to a relaxation approach to the minimization of the waveform misfit. As far as the impedance is concerned, this minimization can be performed efficie

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Chow, Bryant, Yoshihiro Kaneko, Carl Tape, Ryan Modrak, and John Townend. "An automated workflow for adjoint tomography—waveform misfits and synthetic inversions for the North Island, New Zealand." Geophysical Journal International 223, no. 3 (2020): 1461–80. http://dx.doi.org/10.1093/gji/ggaa381.

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SUMMARY We develop and verify an automated workflow for full-waveform tomography based on spectral element and adjoint methods. We choose the North Island, New Zealand as a study area because of its high seismicity, extensive seismic network, and the availability of a candidate ray tomography starting model. To assess the accuracy of this model, we simulated 250 regional earthquakes using a spectral element solver, and compared the resulting synthetics with recorded waveforms. In a 10–30 s passband, reasonable cross-correlation phase and amplitude misfits exist between data and synthetics, whe

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14

Maraschini, Margherita, Daniele Boiero, Sebastiano Foti, and Laura Valentina Socco. "Scale properties of the seismic wavefield perspectives for full-waveform matching." GEOPHYSICS 76, no. 5 (2011): A37—A44. http://dx.doi.org/10.1190/geo2010-0213.1.

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Starting from the nondimensionalization of equations of motion we partition the set of the velocity models in equivalence classes, such that the full waveform of an element in a given class can be calculated from the full waveform of any other element in the same class by scaling model parameters. We give a formal derivation of the seismic wavefield scale properties and we prove their capability through the use of numerical examples. Besides this, we introduce how the scale properties can be used to save computational time in full waveform modeling and inversion. In forward modeling we can use

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15

Zygmuntowska, M., K. Khvorostovsky, V. Helm, and S. Sandven. "Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice." Cryosphere 7, no. 4 (2013): 1315–24. http://dx.doi.org/10.5194/tc-7-1315-2013.

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Abstract. Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types have been analyzed. A set of parameters has been defined to characterize the differences in strength a

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16

Lee, Seong-Hyeon, Min-Suk Kang, Sang-Hong Park, Seung-Yong Shin, Eunjung Yang, and Kyung-Tae Kim. "Inverse Synthetic Aperture Radar Imaging Using Stepped Chirp Waveform." Journal of Korean Institute of Electromagnetic Engineering and Science 25, no. 9 (2014): 930–37. http://dx.doi.org/10.5515/kjkiees.2014.25.9.930.

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17

Cao, D., W. B. Beydoun, S. C. Singh, and A. Tarantola. "A simultaneous inversion for background velocity and impedance maps." GEOPHYSICS 55, no. 4 (1990): 458–69. http://dx.doi.org/10.1190/1.1442855.

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Full‐waveform inversion of seismic reflection data is highly nonlinear because of the irregular form of the function measuring the misfit between the observed and the synthetic data. Since the nonlinearity results mainly from the parameters describing seismic velocities, an alternative to the full nonlinear inversion is to have an inversion method which remains nonlinear with respect to velocities but linear with respect to impedance contrasts. The traditional approach is to decouple the nonlinear and linear parts by first estimating the background velocity from traveltimes, using either trave

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18

Yang, Yushan, Yuanyuan Li, and Tianyou Liu. "1D viscoelastic waveform inversion for Q structures from the surface seismic and zero-offset VSP data." GEOPHYSICS 74, no. 6 (2009): WCC141—WCC148. http://dx.doi.org/10.1190/1.3227151.

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Wave attenuation is an important physical property of hydrocarbon-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a 1D viscoelastic waveform inversion scheme for determining the quality factor [Formula: see text] from the normal-incidence surface seismic and zero-offset vertical seismic profile (VSP) data simultaneously. The joint inversion problem is solved by the damped least-squares method, and the inversion result is successful using synthetic data. The effects of initial model thickness, [Formula: see text] value, and the existenc

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19

Walker, Benjamin J., Shiva Phuyal, Kenta Ishimoto, Chih-Kuan Tung, and Eamonn A. Gaffney. "Computer-assisted beat-pattern analysis and the flagellar waveforms of bovine spermatozoa." Royal Society Open Science 7, no. 6 (2020): 200769. http://dx.doi.org/10.1098/rsos.200769.

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Obstructed by hurdles in information extraction, handling and processing, computer-assisted sperm analysis systems have typically not considered in detail the complex flagellar waveforms of spermatozoa, despite their defining role in cell motility. Recent developments in imaging techniques and data processing have produced significantly improved methods of waveform digitization. Here, we use these improvements to demonstrate that near-complete flagellar capture is realizable on the scale of hundreds of cells, and, further, that meaningful statistical comparisons of flagellar waveforms may be r

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20

Wang, Jie, Ke-Hong Zhu, Li-Na Wang, Xing-Dong Liang, and Long-Yong Chen. "A Novel Orthogonal Waveform Separation Scheme for Airborne MIMO-SAR Systems." Sensors 18, no. 10 (2018): 3580. http://dx.doi.org/10.3390/s18103580.

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In recent years, multi-input multi-output (MIMO) synthetic aperture radar (SAR) systems, which can promote the performance of 3D imaging, high-resolution wide-swath remote sensing, and multi-baseline interferometry, have received considerable attention. Several papers on MIMO-SAR have been published, but the research of such systems is seriously limited. This is mainly because the superposed echoes of the multiple transmitted orthogonal waveforms cannot be separated perfectly. The imperfect separation will introduce ambiguous energy and degrade SAR images dramatically. In this paper, a novel o

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Sheng, Jianming, Alan Leeds, Maike Buddensiek, and Gerard T. Schuster. "Early arrival waveform tomography on near-surface refraction data." GEOPHYSICS 71, no. 4 (2006): U47—U57. http://dx.doi.org/10.1190/1.2210969.

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We develop a waveform-tomography method for estimating the velocity distribution that minimizes the waveform misfit between the predicted and observed early arrivals in space-time seismograms. By fitting the waveforms of early arrivals, early arrival waveform tomography (EWT) naturally takes into account more general wave-propagation effects compared to the high-frequency method of traveltime tomography, meaning that EWT can estimate a wider range of slowness wavenumbers. Another benefit of EWT is more reliable convergence compared to full-waveform tomography, because an early-arrival misfit f

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Li, Yuanming, Bonhwa Ku, Shou Zhang, Jae-Kwang Ahn, and Hanseok Ko. "Seismic Data Augmentation Based on Conditional Generative Adversarial Networks." Sensors 20, no. 23 (2020): 6850. http://dx.doi.org/10.3390/s20236850.

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Realistic synthetic data can be useful for data augmentation when training deep learning models to improve seismological detection and classification performance. In recent years, various deep learning techniques have been successfully applied in modern seismology. Due to the performance of deep learning depends on a sufficient volume of data, the data augmentation technique as a data-space solution is widely utilized. In this paper, we propose a Generative Adversarial Networks (GANs) based model that uses conditional knowledge to generate high-quality seismic waveforms. Unlike the existing me

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Wang, Yi, Xueyi Shang, Zewei Wang, and Rui Gao. "High-Accuracy Location of Microseismic Events in a Strong Inhomogeneous Mining Environment by Optimized Global Full Waveform Inversion." Applied Sciences 10, no. 20 (2020): 7205. http://dx.doi.org/10.3390/app10207205.

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High-accuracy determination of a microseismic (MS) location is the core task in MS monitoring. In this study, a 3D multi-scale grid Green’s function database, depending on recording wavefield frequency band for the target mining area, is pre-generated based on the reciprocity theorem and 3D spectral element method (SEM). Then, a multi-scale global grid search strategy is performed based on this pre-stored Green’s function database, which can be effectively and hierarchically processed by searching for the spatial location. Numerical wavefield modeling by SEM effectively overcomes difficulties

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Baptista, Maria Ana, Jorge Miguel Miranda, Luis Matias, and Rachid Omira. "Synthetic tsunami waveform catalogs with kinematic constraints." Natural Hazards and Earth System Sciences 17, no. 7 (2017): 1253–65. http://dx.doi.org/10.5194/nhess-17-1253-2017.

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Abstract. In this study we present a comprehensive methodology to produce a synthetic tsunami waveform catalogue in the northeast Atlantic, east of the Azores islands. The method uses a synthetic earthquake catalogue compatible with plate kinematic constraints of the area. We use it to assess the tsunami hazard from the transcurrent boundary located between Iberia and the Azores, whose western part is known as the Gloria Fault. This study focuses only on earthquake-generated tsunamis. Moreover, we assume that the time and space distribution of the seismic events is known. To do this, we comput

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Tian, Xuanxuan, Tingting Zhang, Qinyu Zhang, and Zhaohui Song. "HRR Profiling on Integrated Radar-Communication Systems Using OFDM-PCSF Signals." Mathematical Problems in Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/5357187.

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In order to improve both the transmission data rate and the range resolution simultaneously in integrated radar-communication (RadCom) systems, orthogonal frequency-division multiplexing with phase-coded and stepped-frequency (OFDM-PCSF) waveform is proposed. A corresponding high resolution range (HRR) profile generation method is also presented. We first perform OFDM-PCSF waveform design by combining the intrapulse phase coding with the interpulse stepped-frequency modulation. We then give the ambiguity function (AF) based on the presented waveforms. Then, the synthetic range profile (SRP) pr

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Kong, Fan-Tong, Can Jiang, Yuan-Da Su, and Xiao-Ming Tang. "A multiple filtering and correlation array signal processing technique for cased-hole acoustic logging and applications." Interpretation 8, no. 3 (2020): SL1—SL8. http://dx.doi.org/10.1190/int-2019-0116.1.

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In cased-hole acoustic logging, estimating the formation velocity is often problematic when the casing is poorly bonded with the formation. The overwhelmingly large casing waves dominate the measured waveforms and overlap with the low-coherence, weak formation arrival, contributing to the failure of conventional semblance processing method. To tackle this problem, we have developed a filtered frequency semblance array waveform signal processing technique. The multiple filter technique is first used to filter the measured waveforms. We then apply the [Formula: see text]th root stacking method t

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Maurer, Hansruedi, Stewart A. Greenhalgh, Edgar Manukyan, Stefano Marelli, and Alan G. Green. "Receiver-coupling effects in seismic waveform inversions." GEOPHYSICS 77, no. 1 (2012): R57—R63. http://dx.doi.org/10.1190/geo2010-0402.1.

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Seismic waveform-inversion offers opportunities for detailed characterization of the subsurface. However, its full potential can only be exploited when any systematic source and receiver effects are either carefully avoided or appropriately accounted for during the inversions. Repeated crosshole measurements in the Mont Terri (Switzerland) underground laboratory have revealed that receiver coupling may significantly affect the seismic waveforms. More seriously, coupling conditions may vary during the course of a monitoring experiment. To address this problem, we have developed a novel scheme t

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Plessix, René-Édouard, and Tadas Krupovnickas. "Low-frequency, long-offset elastic waveform inversion in the context of velocity model building." Leading Edge 40, no. 5 (2021): 342–47. http://dx.doi.org/10.1190/tle40050342.1.

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Classic imaging approaches consist of splitting the earth into background and reflectivity models. When justified, this separation of scale is quite powerful, although this approach relies on some smoothness and weak contrast assumptions. This approach allows for the imaging methods to be based on acoustic wave propagation after having identified the compressional waves through picking or signal processing. Over the past years, wave-equation tomography and waveform inversion approaches have become routine, complementing the classic approaches to derive background models. They do not rely on hi

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Liu, Yike, Bin He, Zhendong Zhang, Yingcai Zheng, and Peng Li. "Reflection intensity waveform inversion." GEOPHYSICS 85, no. 3 (2020): R263—R273. http://dx.doi.org/10.1190/geo2019-0590.1.

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Traditional iteration-based full-waveform inversion (FWI) methods encounter serious challenges if the initial velocity model is far from the true model or if the observed data are lacking low-frequency content. As such, the optimization algorithm may be trapped in local minima and fail to go to a global optimal model. In addition, the traditional FWI method requires long-offset data to update the deep structure of a velocity model with diving waves. To overcome the disadvantages of traditional FWI under these circumstances, we have developed a reflection intensity waveform inversion method. Th

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30

Pan, Yudi, Lingli Gao, and Renat Shigapov. "Multi-objective waveform inversion of shallow seismic wavefields." Geophysical Journal International 220, no. 3 (2019): 1619–31. http://dx.doi.org/10.1093/gji/ggz539.

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SUMMARY It has been increasingly popular to use shallow-seismic full-waveform inversion (FWI) to reconstruct near-surface structures. Conventional FWI tries to resolve the earth model by minimizing the difference between observed and synthetic seismic data using a certain criterion (conventionally, l2-norm of waveform difference). In this paper, we propose a multi-objective waveform inversion (MOWI) in which the similarity of data is quantified and minimized using multiple criteria simultaneously. By doing so, we expand the dimensionality of objective space as well as the mapping from data spa

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31

Tao, Kai, Stephen P. Grand, and Fenglin Niu. "Full-waveform inversion of triplicated data using a normalized-correlation-coefficient-based misfit function." Geophysical Journal International 210, no. 3 (2017): 1517–24. http://dx.doi.org/10.1093/gji/ggx249.

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Summary In seismic full-waveform inversion (FWI), the choice of misfit function determines what information in data is used and ultimately affects the resolution of the inverted images of the Earth's structure. Misfit functions based on traveltime have been successfully applied in global and regional tomographic studies. However, wave propagation through the upper mantle results in multiple phases arriving at a given receiver in a narrow time interval resulting in complicated waveforms that evolve with distance. To extract waveform information as well as traveltime, we use a misfit function ba

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Minakov, Alexander, Henk Keers, Dmitriy Kolyukhin, and Hans Christian Tengesdal. "Acoustic Waveform Inversion for Ocean Turbulence." Journal of Physical Oceanography 47, no. 6 (2017): 1473–91. http://dx.doi.org/10.1175/jpo-d-16-0236.1.

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AbstractThe seismic oceanography method is based on extracting and stacking the low-frequency acoustic energy scattered by the ocean heterogeneity. However, a good understanding on how this acoustic wavefield is affected by physical processes in the ocean is still lacking. In this work an acoustic waveform modeling and inversion method is developed and applied to both synthetic and real data. In the synthetic example, the temperature field is simulated as a homogeneous Gaussian isotropic random field with the Kolmogorov–Obukhov spectrum superimposed on a background stratified ocean structure.

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Williams, David E., and Charles A. Langston. "Observational Test for Wave Propagation Effects in Local Earthquake Seismograms." Seismological Research Letters 61, no. 2 (1990): 109–16. http://dx.doi.org/10.1785/gssrl.61.2.109.

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Abstract Strong motion data for aftershocks of the 1982 Miramichi earthquake are analyzed to determine site effects on recorded waveforms. Although aftershocks vary in source mechanism, the complicated vector particle motion of P and S arrivals are often coherent between events recorded at the same station. This suggests that near-surface receiver structure has a significant effect on the recorded waveforms. Resonance features dominate the wavetrains with P reverberations existing on the vertical components and S reverberations prominent on the radial components indicating near vertical incide

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Gao, Qi, Eduard Makhoul, Maria Escorihuela, et al. "Analysis of Retrackers’ Performances and Water Level Retrieval over the Ebro River Basin Using Sentinel-3." Remote Sensing 11, no. 6 (2019): 718. http://dx.doi.org/10.3390/rs11060718.

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Satellite altimeters have been used to monitor river and reservoir water levels, from which water storage estimates can be derived. Inland water altimetry can, therefore, play an important role in continental water resource management. Traditionally, satellite altimeters were designed to monitor homogeneous surfaces such as oceans or ice sheets, resulting in poor performance over small inland water bodies due to the contribution from land contamination in the returned waveforms. The advent of synthetic aperture radar (SAR) altimetry (with its improved along-track spatial resolution) has enable

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Warner, Michael, and Lluís Guasch. "Adaptive waveform inversion: Theory." GEOPHYSICS 81, no. 6 (2016): R429—R445. http://dx.doi.org/10.1190/geo2015-0387.1.

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Conventional full-waveform seismic inversion attempts to find a model of the subsurface that is able to predict observed seismic waveforms exactly; it proceeds by minimizing the difference between the observed and predicted data directly, iterating in a series of linearized steps from an assumed starting model. If this starting model is too far removed from the true model, then this approach leads to a spurious model in which the predicted data are cycle skipped with respect to the observed data. Adaptive waveform inversion (AWI) provides a new form of full-waveform inversion (FWI) that appear

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Zhang, Zhen-dong, and Tariq Alkhalifah. "Local-crosscorrelation elastic full-waveform inversion." GEOPHYSICS 84, no. 6 (2019): R897—R908. http://dx.doi.org/10.1190/geo2018-0660.1.

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Full-waveform inversion (FWI) in its classic form is a method based on minimizing the [Formula: see text] norm of the difference between the observed and simulated seismic waveforms at the receiver locations. The objective is to find a subsurface model that reproduces the full waveform including the traveltimes and amplitudes of the observed seismic data. However, the widely used [Formula: see text]-norm-based FWI faces many issues in practice. The point-wise comparison of waveforms fails when the phase difference between the compared waveforms of the predicted and observed data is larger than

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Zhang, Xin, and Andrew Curtis. "Variational full-waveform inversion." Geophysical Journal International 222, no. 1 (2020): 406–11. http://dx.doi.org/10.1093/gji/ggaa170.

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SUMMARY Seismic full-waveform inversion (FWI) can produce high-resolution images of the Earth’s subsurface. Since full-waveform modelling is significantly nonlinear with respect to velocities, Monte Carlo methods have been used to assess image uncertainties. However, because of the high computational cost of Monte Carlo sampling methods, uncertainty assessment remains intractable for larger data sets and 3-D applications. In this study, we propose a new method called variational FWI, which uses Stein variational gradient descent to solve FWI problems. We apply the method to a 2-D synthetic exa

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Li, Shengjun, Bo Zhang, Xueshan Yong, and Wang Shangxu. "Seismic quality factor estimation using prestack seismic gathers: A simulated annealing approach." Interpretation 8, no. 2 (2020): T441—T451. http://dx.doi.org/10.1190/int-2019-0066.1.

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Fluid movement and grain boundary friction are the two main factors affecting the anelastic attenuation of seismic data. The quality factor ([Formula: see text]) quantifies the degree of anelastic attenuation and is commonly used in assisting the identification of gas reservoirs. We can accurately compute [Formula: see text] if we obtain the accurate amplitude spectrum of seismic wavelets at refereed and at target time indexes of the seismic profile. However, it is very difficult to obtain the accurate wavelets at the referred and target time indexes. Instead, we usually compare the changes of

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Yang, Jungang, Xiaotao Huang, Tian Jin, John Thompson, and Zhimin Zhou. "Synthetic Aperture Radar Imaging Using Stepped Frequency Waveform." IEEE Transactions on Geoscience and Remote Sensing 50, no. 5 (2012): 2026–36. http://dx.doi.org/10.1109/tgrs.2011.2170176.

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He, Xiao-bo, Hui-lan Zhou, Yan-lu Ma, and Feng-lin Niu. "Synthetic study on SS waveform splitting and complication." Acta Seismologica Sinica 21, no. 1 (2008): 35–45. http://dx.doi.org/10.1007/s11589-008-0035-5.

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Neff, Dennis B. "Incremental pay thickness modeling of hydrocarbon reservoirs." GEOPHYSICS 55, no. 5 (1990): 556–66. http://dx.doi.org/10.1190/1.1442867.

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The one-dimensional convolution model or synthetic seismogram provides more information about the seismic waveform expression of hydrocarbon reservoirs when petrophysical data (porosity, shale volume, water saturation, etc.) are systematically integrated into the seismogram generation process. Use of this modeling technique, herein called Incremental Pay Thickness (IPT) modeling, has provided valuable insights concerning the seismic response of several offshore Gulf of Mexico amplitude anomalies. Through integration of the petrophysical data, comparisons between seismic waveform response and e

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Shin, Changsoo, and Dong-Joo Min. "Waveform inversion using a logarithmic wavefield." GEOPHYSICS 71, no. 3 (2006): R31—R42. http://dx.doi.org/10.1190/1.2194523.

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Although waveform inversion has been studied extensively since its beginning [Formula: see text] ago, applications to seismic field data have been limited, and most of those applications have been for global-seismology- or engineering-seismology-scale problems, not for exploration-scale data. As an alternative to classical waveform inversion, we propose the use of a new, objective function constructed by taking the logarithm of wavefields, allowing consideration of three types of objective function, namely, amplitude only, phase only, or both. In our wave form inversion, we estimate the source

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Aldenhoff, Wiebke, Céline Heuzé, and Leif E. B. Eriksson. "Sensitivity of Radar Altimeter Waveform to Changes in Sea Ice Type at Resolution of Synthetic Aperture Radar." Remote Sensing 11, no. 22 (2019): 2602. http://dx.doi.org/10.3390/rs11222602.

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Radar altimetry in the context of sea ice has mostly been exploited to retrieve basin-scale information about sea ice thickness. In this paper, we investigate the sensitivity of altimetric waveforms to small-scale changes (a few hundred meters to about 10 km) of the sea ice surface. Near-coincidental synthetic aperture radar (SAR) imagery and CryoSat-2 altimetric data in the Beaufort Sea are used to identify and study the spatial evolution of altimeter waveforms over these features. Open water and thin ice features are easily identified because of their high peak power waveforms. Thicker ice f

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Stump, Brian W. "Constraints on explosive sources with spall from near-source waveforms." Bulletin of the Seismological Society of America 75, no. 2 (1985): 361–77. http://dx.doi.org/10.1785/bssa0750020361.

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Abstract Spall, the tensile failure of a material due to high stress loading, has been observed in a number of contained and surface explosions. The phenomenon results in a repartition of the initial spherical explosion energy source, yielding a second energy source which is cylindrical and delayed in time. Recent spall models by Day et al. (1983) demanding conservation of momentum have shown the phenomenon to have little contribution to 20-sec surface waves. These models are extended to include the effect of the process on near-source seismograms. The spall model is constrained by observation

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Wang, Liang, Chao Xuan Shang, Qiang He, Zhuang Zhi Han, and Hong Wei Ren. "Study on Imaging Algorithm for Stepped-Frequency Chirp Train Waveform." Applied Mechanics and Materials 347-350 (August 2013): 1101–5. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1101.

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A range profile synthetic algorithm of the stepped-frequency chirp train waveform is designed to obtain HRRP (High Resolution Range Profile) in this paper. Based on waveform model, grating lobes restraining method is proposed with the help of autocorrelation function. Due to the matched filter operation, image energy spill over the close range bins, which causes “ghost images”. Set parameters of inner pulse bandwidth, stepped frequency and chirp compression envelop sampling frequency properly, and then carry the synthetic algorithm, the “ghost images” are restrained. All of the results are val

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Liu, Zhiyang, and Jie Zhang. "Joint traveltime, waveform, and waveform envelope inversion for near-surface imaging." GEOPHYSICS 82, no. 4 (2017): R235—R244. http://dx.doi.org/10.1190/geo2016-0356.1.

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The first-arrival traveltimes without large offsets constrain very shallow velocities, the waveform envelope presents low-frequency data, and the high-frequency waveform itself includes information regarding structural details. We have developed a joint traveltime, waveform, and waveform envelope (JTWE) inversion method for inverting near-surface velocity structures. By inverting three types of data, we are able to recover the low- and high-wavenumber structures and mitigate the cycle-skipping problem in waveform inversion. The calculation of traveltimes and raypaths is fast. Most of the compu

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Wang, Zhikai, Satish C. Singh, and Mark Noble. "True-amplitude versus trace-normalized full waveform inversion." Geophysical Journal International 220, no. 2 (2019): 1421–35. http://dx.doi.org/10.1093/gji/ggz532.

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SUMMARY Full waveform inversion (FWI) is a powerful method to estimate high-resolution physical parameters of the subsurface by iteratively minimizing the misfit between the observed and synthetic seismic data. Standard FWI algorithms measure seismic misfit between amplitude-preserved seismic data (true-amplitude FWI). However, in order to mitigate the variations in sources and recording systems acquired on complex geological structures and the physics that cannot be modelled using an approximation of the seismic wave equation, the observed and synthetic seismic data are normalized trace-by-tr

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Zhang, Miao, Min Liu, Alexandre Plourde, Feng Bao, Ruijia Wang, and John Gosse. "Source Characterization for Two Small Earthquakes in Dartmouth, Nova Scotia, Canada: Pushing the Limit of Single Station." Seismological Research Letters 92, no. 4 (2021): 2540–50. http://dx.doi.org/10.1785/0220200297.

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Abstract A pair of small earthquakes (MN 2.4 and 2.6, Earthquakes Canada) hit the city of Dartmouth, Nova Scotia, Canada, in early March 2020. The events were recorded by three seismic stations within 200 km, but only one station (HAL, &lt;10 km) is close enough to offer high-quality broadband signals. In this study, we explore their source parameters using the nearest station through waveform modeling. A nearby quarry blast (MN 2.0) with known Global Positioning System coordinates is adopted as a reference for regional velocity model building and location calibration. We first build a hal

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Boonyasiriwat, Chaiwoot, Gerard T. Schuster, Paul Valasek, and Weiping Cao. "Applications of multiscale waveform inversion to marine data using a flooding technique and dynamic early-arrival windows." GEOPHYSICS 75, no. 6 (2010): R129—R136. http://dx.doi.org/10.1190/1.3507237.

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A recently developed time-domain multiscale waveform tomography (MWT) method is applied to synthetic and field marine data. Although the MWT method was already applied to synthetic data, the synthetic data application leads to a development of a hybrid method between waveform tomography and the salt flooding technique commonly use in subsalt imaging. This hybrid method can overcome a convergence problem encountered by inversion with a traveltime velocity tomogram and successfully provides an accurate and highly resolved velocity tomogram for the 2D SEG/EAGE salt model. In the application of MW

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He, Gang, Peng Bai, Wei Dong Peng, et al. "A Joint Transmitter-Receiver Adaptive STAP Algorithm of Clutter Suppression for Airborne MIMO Radar." Applied Mechanics and Materials 236-237 (November 2012): 1238–42. http://dx.doi.org/10.4028/www.scientific.net/amm.236-237.1238.

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In airborne MIMO radar, distributing characteristic of clutter have some relation with transmitted waveform diversity and Waveform Synthetic Structure. In this paper , we use the predominance of Transmitted waveform diversity on airborne MIMO radar, A joint transmitter-receiver adaptive dispose algorithm is proposed, and STAP dispose is done in wave, air and time dimension for airborne MIMO radar. The result of simulations show the proposed algorithm achieved the aim of clutter joint suppression, sequentially, which increase the performance of clutter suppression on airborne MIMO radar.

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