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Journal articles on the topic 'Stolt's migration'

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Published: 4 June 2021

Last updated: 12 February 2022

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1

Whiting, P. "Extended FK domain migration ? An efficient variable velocity algorithm." Exploration Geophysics 20, no. 2 (1989): 281. http://dx.doi.org/10.1071/eg989281.

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Constant velocity FK domain migration, as developed by Stolt in 1978, has significant performance advantages over all other commercially available migration algorithms.However, even with Stolt's pre-migration time stretching (or psuedo-depth conversion), this algorithm suffers serious accuracy problems in the presence of any significant velocity variations. This paper develops a method of extending the accuracy of FK domain migration to steep dips in arbitrary velocity fields. The basis of the new method is the partitioning of the unmigrated data set into dip ranges and computing unique time s

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2

Garcia, D., L. L. Tarnec, S. Muth, E. Montagnon, J. Poree, and G. Cloutier. "Stolt's f-k migration for plane wave ultrasound imaging." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 60, no. 9 (2013): 1853–67. http://dx.doi.org/10.1109/tuffc.2013.2771.

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3

Mikulich, Weston, and Dave Hale. "Steep‐dip v(z) imaging from an ensemble of Stolt‐like migrations." GEOPHYSICS 57, no. 1 (1992): 51–59. http://dx.doi.org/10.1190/1.1443188.

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Stolt migration is often performed with many different velocities, creating a cube (or ensemble) of migrated constant‐velocity sections. With this ensemble, an interpreter can quickly, even interactively, carve out a single, variable‐velocity time migration. Unfortunately, the variable‐velocity section obtained in this way cannot image steep dips correctly. Phase‐shift (i.e., Gazdag) migration accurately images reflections from steep interfaces where velocity varies with depth. However, it is computationally slow compared to Stolt’s f-k migration, its constant‐velocity counterpart. Similaritie

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4

Stolt, Robert H. "A prestack residual time migration operator." GEOPHYSICS 61, no. 2 (1996): 605–7. http://dx.doi.org/10.1190/1.1443987.

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Larner and Beasley (1987) present cascaded migration as a way to increase the power and effectiveness of relatively simple migration methods. In particular, f-k migration (Stolt, 1978) can be made to accommodate a depth‐dependent velocity as a cascade of constant‐velocity migrations. The core concept is that data which have been migrated with an approximate velocity can be effectively migrated to their true velocity by migrating with a velocity that is equal to the square root of the difference between the squares of the true and approximate velocities.

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5

Margrave, Gary F. "Direct Fourier migration for vertical velocity variations." GEOPHYSICS 66, no. 5 (2001): 1504–14. http://dx.doi.org/10.1190/1.1487096.

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The Stolt f‐x migration algorithm is a direct (i.e. nonrecursive) Fourier‐domain technique based on a change of variables, or equivalently a mapping, that converts the unmigrated spectrum to the migrated spectrum. The algorithm is simple and efficient but limited to constant velocity. A v(z) f‐k migration method, capable of very high accuracy for vertical velocity variations, can be formulated as a nonstationary filter that avoids the change of variables. The result is a direct Fourier‐domain process that, for each wavenumber, applies a nonstationary migration filter to a vector of input frequ

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6

Beasley, Craig J., Walt Lynn, Ken Larner, and Hung Nguyen. "Cascaded f-k migration: Removing the restrictions on depth‐varying velocity." GEOPHYSICS 53, no. 7 (1988): 881–93. http://dx.doi.org/10.1190/1.1442525.

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Stolt’s frequency‐wavenumber (f-k) method is computationally efficient and has unlimited dip accuracy for constant‐velocity media. Although the f-k method can handle moderate vertical velocity variations, errors become unacceptable for steep dips when such variations are large. This paper describes an extension to the f-k method that removes its restrictions on vertical velocity variation, yielding accuracy comparable to phase‐shift migration at only a fraction of the computational time. This extension of the f-k method is based on partitioning the velocity field, just as in cascaded finite‐di

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7

Kim, Y. C., R. Gonzalez, and J. R. Berryhill. "Recursive wavenumber‐frequency migration." GEOPHYSICS 54, no. 3 (1989): 319–29. http://dx.doi.org/10.1190/1.1442657.

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There are many approaches for migrating seismic data using velocities varying only with depth. These methods are capable of accommodating quasi‐continuous vertical velocity variation at the expense of a considerably larger amount of computation than with the Stolt method, which assumes a constant velocity for the subsurface of the earth. However, the errors involved in estimating migration velocities from seismic data are often too large to justify such a large amount of computational effort. Furthermore, because there is a resolution limit in velocity estimation, a time‐depth curve based on t

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8

Biondi, Biondo, and Gopal Palacharla. "3-D prestack migration of common‐azimuth data." GEOPHYSICS 61, no. 6 (1996): 1822–32. http://dx.doi.org/10.1190/1.1444098.

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In principle, downward continuation of 3-D prestack data should be carried out in the 5-D space of full 3-D prestack geometry (recording time, source surface location, and receiver surface location), even when the data sets to be migrated have fewer dimensions, as in the case of common‐azimuth data sets that are only four dimensional. This increase in dimensionality of the computational space causes a severe increase in the amount of computations required for migrating the data. Unless this computational efficiency issue is solved, 3-D prestack migration methods based on downward continuation

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9

Rothman, Daniel H., Stewart A. Levin, and Fabio Rocca. "Residual migration: Applications and limitations." GEOPHYSICS 50, no. 1 (1985): 110–26. http://dx.doi.org/10.1190/1.1441822.

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The correct migration of seismic data depends on the accuracy of the chosen velocity model. Rocca and Salvador (1982) showed that small errors in the velocity model may be efficiently corrected by applying a residual migration to previously migrated data, rather than remigrating the original data with a corrected velocity field. The effective velocity used in this residual processing is usually small compared to the original migration velocity. This decreases computational cost relative to a full migration, and allows the initial migration to be done with a less accurate but faster algorithm t

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10

Sidiq, Aditya P., Henry M. Manik, and Tumpal B. Nainggolan. "STUDI KOMPARASI METODE MIGRASI SEISMIK DALAM MENGKARAKTERISASI RESERVOIR MIGAS DI BLOK KANGEAN, LAUT BALI MENGGUNAKAN INVERSI IMPEDANSI AKUSTIK BERBASIS MODEL." Jurnal Ilmu dan Teknologi Kelautan Tropis 11, no. 1 (2019): 205–19. http://dx.doi.org/10.29244/jitkt.v11i1.23028.

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ABSTRAK Karakterisasi reservoir menjadi penting dalam tahapan eksplorasi minyak dan gas bumi. Salah satu hal yang dibutuhkan untuk mencapai keakuratan dalam mengkarakterisasi reservoir adalah penampang seismik yang sesuai dengan penampang aslinya. Struktur lapisan bumi yang kompleks mengakibatkan gelombang terdifraksi, sehingga penampang seismik mengalami pembelokan dari posisi sebenarnya. Penelitian ini menerapkan metode migrasi seismik Kirchhoff dan Stolt (F-K) untuk mengembalikan posisi reflektor pada waktu dan kedalaman yang sebenarnya pada data seismik 2D di Perairan Utara Bali. Data seis

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11

Jung, Haewon, and Kangwook Kim. "Autofocusing Technique Based on Generalized Multilayer Stolt Migration." IEEE Transactions on Geoscience and Remote Sensing 56, no. 3 (2018): 1386–93. http://dx.doi.org/10.1109/tgrs.2017.2762365.

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12

Sava, Paul C. "Prestack residual migration in the frequency domain." GEOPHYSICS 68, no. 2 (2003): 634–40. http://dx.doi.org/10.1190/1.1567233.

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Prestack Stolt residual migration can be applied to seismic images that are depth migrated using wavefield extrapolation techniques. This method has significant advantages over other methods that estimate interval velocity functions for depth migration. It is more accurate than methods that are based on focusing the stack of migrated images by a residual NMO operation, so it provides a more accurate estimate of the correct migration velocities. Also, it is conceptually simpler and easier to implement than traveltime tomography methods. Although the theory is developed assuming constant velocit

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13

Yang, Haining, Tingjun Li, Na Li, Zhiming He, and Qing Huo Liu. "Efficient Stolt Migration for Large Nonuniform Single Borehole Radar Surveys." IEEE Transactions on Geoscience and Remote Sensing 54, no. 12 (2016): 7250–60. http://dx.doi.org/10.1109/tgrs.2016.2598820.

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14

Gardner, Gerald H. F., and Anat Canning. "AVA analysis after velocity-independent DMO and imaging." GEOPHYSICS 63, no. 2 (1998): 686–91. http://dx.doi.org/10.1190/1.1444368.

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A common midpoint (CMP) gather usually provides amplitude variation with offset (AVO) information by displaying the reflectivity as the peak amplitude of symmetrical deconvolved wavelets. This puts a reflection coefficient R at every offset h, giving a function R(h). But how do we link h with the angle of incidence, θ, to get the reflectivity function, R(θ)? This is necessary for amplitude versus angle-of-incidence (AVA) analysis. One purpose of this paper is to derive formulas for this linkage after velocity-independent dip-moveout (DMO), done by migrating radial sections, and prestack zero-o

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15

Ibrahim, Amr, and Mauricio D. Sacchi. "Fast simultaneous seismic source separation using Stolt migration and demigration operators." GEOPHYSICS 80, no. 6 (2015): WD27—WD36. http://dx.doi.org/10.1190/geo2015-0044.1.

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16

Jung, Haewon, Woong Kang, and Kangwook Kim. "Multilayer Stolt Migration Algorithm for Subsurface Target Imaging in Oblique Layers." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 10, no. 10 (2017): 4295–303. http://dx.doi.org/10.1109/jstars.2016.2615867.

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17

Larner, Ken, Craig J. Beasley, and Walt Lynn. "In quest of the flank." GEOPHYSICS 54, no. 6 (1989): 701–17. http://dx.doi.org/10.1190/1.1442698.

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Primarily through synthetic and field data examples, this paper reviews the benefits of recent developments in time migration of seismic data and reveals limitations, some of them fundamental, that keep elusive the goal of imaging steep events with full accuracy. Even where velocity varies only with depth and, hence, time migration should suffice, accurate imaging of very steep events requires that the velocity structure be known with considerable precision and be finely sampled in depth. This sensitivity of migration accuracy to detail in velocity structure is attributable to the sensitivity

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18

Li, Chao, Yi Lin, Wenmin Lv, and Jinhai Zhang. "Eliminating above-surface diffractions from ground-penetrating radar data using iterative Stolt migration." GEOPHYSICS 86, no. 1 (2021): H1—H11. http://dx.doi.org/10.1190/geo2019-0796.1.

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Above-surface diffractions (ASDs) received by unshielded ground-penetrating radar (GPR) antennas are known to contaminate subsurface reflections and diffractions. Existing ASD-removal methods either leave relatively strong residual ASDs within subsurface reflections or attenuate them excessively. We have developed an iterative migration-based ASD-removal method to address this issue that separates ASDs from subsurface reflections via surgical mute. First, we isolate ASDs within the GPR profile using an optimal window function, generated using the focal center of ASDs within the migrated domain

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19

Qu, Lele, Zhen Li, and Aly E. Fathy. "Compressive sensing-based Stolt migration imaging algorithm for impulse through-the-wall radar." Electronics Letters 56, no. 20 (2020): 1074–77. http://dx.doi.org/10.1049/el.2020.1606.

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20

Brzostowski, Matthew A., Fred F. C. Snyder, and Patrick J. Smith. "Efficient one‐pass 3-D time migration." GEOPHYSICS 61, no. 6 (1996): 1833–45. http://dx.doi.org/10.1190/1.1444099.

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An efficient one‐pass 3-D time migration algorithm is introduced as an alternative to Ristow’s splitting approach. This algorithm extends Black and Leong’s [Formula: see text] approach with a time‐dependent Stolt stretch operation called dilation. Migration using [Formula: see text] dilation consists of a single pass over the 3-D data volume after [Formula: see text] slices are formed with each [Formula: see text] slice downward continued independently. A number of downward continuation algorithms based upon the 3-D wave equation may be used. Dilation accommodates any lateral variations in vel

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21

Hargreaves, N. D., and A. J. Calvert. "Inverse Q filtering by Fourier transform." GEOPHYSICS 56, no. 4 (1991): 519–27. http://dx.doi.org/10.1190/1.1443067.

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Although some attention has been paid to the idea that seismic migration is equivalent to a type of deconvolution (of the spatial wavelet), less thought has been given to the opposite perspective: that deconvolution (of the earth Q filter) might itself be equivalent to a form of migration. The key point raised in this paper is that a dispersive 1-D backward propagation can form the basis of a number of different algorithms for inverse Q filtering, each of which is akin to a particular migration algorithm. An especially efficient algorithm can be derived by means of a coordinate transformation

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22

Sakamoto, Takuya, Toru Sato, Pascal J. Aubry, and Alexander G. Yarovoy. "Ultra-Wideband Radar Imaging Using a Hybrid of Kirchhoff Migration and Stolt F-K Migration With an Inverse Boundary Scattering Transform." IEEE Transactions on Antennas and Propagation 63, no. 8 (2015): 3502–12. http://dx.doi.org/10.1109/tap.2015.2431725.

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23

Dutta, Somaditya. "On: “Migration by Fourier transform,” by R.H. Stolt (January 1978 GEOPHYSICS, 43, p. 23–48)." GEOPHYSICS 60, no. 5 (1995): 1583. http://dx.doi.org/10.1190/1.1443892.

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24

Gong, Xiangbo, Fei Feng, Xuming Jiao, and Shengchao Wang. "Deblending using an improved apex-shifted hyperbolic radon transform based on the Stolt migration operator." Journal of Geophysics and Engineering 14, no. 5 (2017): 1115–23. http://dx.doi.org/10.1088/1742-2140/aa7270.

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25

Grosch, Theodore, and Cyril Okhio. "Modulation Linearization Technique for FM/CW SAR Image Processing Using Range Migration." Applied Sciences 11, no. 16 (2021): 7410. http://dx.doi.org/10.3390/app11167410.

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Linear FMCW radar suffers from impairments in range and range rate if there are errors in the modulation rate or phase discontinuities. Often, this is a result of a nonlinearity of the voltage-controlled oscillator that is in the source of the transmit and receive local oscillator. The nonlinearity can be corrected at the source by using a nonlinear control voltage or by processing the received beat frequency. Any signal processing using the later method leads to computation time and energy costs, which can be considerable in some applications. When the range migration algorithm using the Stol

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26

Cohen, Jack K. "Asymptotic elastic Green’s tensor." GEOPHYSICS 53, no. 7 (1988): 992–94. http://dx.doi.org/10.1190/1.1442536.

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The Green’s function for the acoustic wave equation has been an essential ingredient in obtaining frequency inversion formulas in the acoustic limit (Cohen and Bleistein, 1979; Clayton and Stolt, 1981; Beylkin, 1985; Cohen et al., 1986; Bleistein et al., 1987). Similarly, the Green’s tensor is required for inversions based on the elastic wave equations. Indeed, Kuo and Dai (1984) and Dai and Kuo (1986) have already used an approximation to this tensor to derive a migration result for two‐component seismic data in the case of a homogeneous medium.

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27

Trad, Daniel. "Interpolation and multiple attenuation with migration operators." GEOPHYSICS 68, no. 6 (2003): 2043–54. http://dx.doi.org/10.1190/1.1635058.

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A hyperbolic Radon transform (RT) can be applied with success to attenuate or interpolate hyperbolic events in seismic data. However, this method fails when the hyperbolic events have apexes located at nonzero offset positions. A different RT operator is required for these cases, an operator that scans for hyperbolas with apexes centered at any offset. This procedure defines an extension of the standard hyperbolic RT with hyperbolic basis functions located at every point of the data gather. The mathematical description of such an operator is basically similar to a kinematic poststack time‐migr

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28

Loewenthal, Dan, Paul L. Stoffa, and Eduardo L. Faria. "Suppressing the unwanted reflections of the full wave equation." GEOPHYSICS 52, no. 7 (1987): 1007–12. http://dx.doi.org/10.1190/1.1442352.

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In many instances in exploration geophysics we are interested in the so‐called one‐way wave equation. This equation allows the wave fields to propagate in the positive depth direction, but not in the reverse (−Z) direction. Some modeling and migration methods, such as the f-k method (Stolt, 1978) and the phase‐shift method (Gazdag, 1978), produce in a natural way the one‐way wave equation. The main advantage of the one‐way wave equation is that it does not give rise to multiples or interlayer reverberations and enables the observation of primary events only.

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29

Kamenetsky, Rina. "Vegetative Propagation of Species of Genus Allium L." Water Science and Technology 27, no. 7-8 (1993): 511–17. http://dx.doi.org/10.2166/wst.1993.0589.

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The genus Allium L. consists of about 500 species in the Northern hemisphere and includes a large number of useful plants. The highly variable underground organs of Allium species - rhizomes and bulbs - have the function of storing food and moisture in severe environmental conditions. Their other very important function - vegetative reproduction and propagation - increases the chances of survival and supports the genetic stability of natural populations. Among about 40 species studied, 5 types of vegetative reproduction and propagation are distinguishable. The formation of apical buds, daughte

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30

Bednar, J. Bee. "A brief history of seismic migration." GEOPHYSICS 70, no. 3 (2005): 3MJ—20MJ. http://dx.doi.org/10.1190/1.1926579.

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In this article, I attempt to focus on the chronology of seismic imaging. I start in the mid-1920s, progress through the human “computer”-based methods of the 1940s and 1950s, discuss the emergence of digital wave-equation technology in the 1960s and early 1970s, and finally end with a review of the present. I include a bit of speculation about the future of seismic imaging, but the meat of the article is on seismic-imaging history. Based on the timing of their publications, I claim there are three key contributors to the theoretical developments of modern seismic imaging: F. Rieber, J. G. Hag

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31

Bajewski, Łukasz, Aleksander Wilk, and Andrzej Urbaniec. "Porównanie modeli prędkości obliczonych z wykorzystaniem różnych wariantów prędkości i algorytmów na profilu sejsmicznym 2D na potrzeby migracji czasowej po składaniu." Nafta-Gaz 77, no. 7 (2021): 419–28. http://dx.doi.org/10.18668/ng.2021.07.01.

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This article presents a construction method of the velocity field for poststack time migration for 2D seismic calculated on the basis of interval velocities in boreholes and structural interpretation, as well as the results of poststack time migration based on this solution. Three velocity field models have been developed. The models used differ in the way of spatial interpolation and extrapolation in the adopted calculation grid in the depth domain, which was created on the basis of a structural interpretation of 2D seismic profiles. Three methods of interpolation and extrapolation were used:

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32

Wapenaar, C. P. A. "Representation of seismic sources in the one‐way wave equations." GEOPHYSICS 55, no. 6 (1990): 786–90. http://dx.doi.org/10.1190/1.1442892.

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One‐way extrapolation of downgoing and upgoing acoustic waves plays an essential role in the current practice of seismic migration (Berkhout, 1985; Stolt and Benson, 1986; Claerbout, 1985; Gardner, 1985). Generally, one‐way wave equations are derived for the source‐free situation. Sources are then represented as boundary conditions for the one‐way extrapolation problem. This approach is valid provided the source representation is done with utmost care. For instance, it is not correct to represent a monopole source by a spatial delta function and to use this as input data for a standard one‐way

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33

Zhou, Huilin, Xing Wan, Wei Li, and Yuling Jiang. "Combining F-K Filter with Minimum Entropy Stolt Migration Algorithm for Subsurface Object Imaging and Background Permittivity Estimation." Procedia Engineering 23 (2011): 636–41. http://dx.doi.org/10.1016/j.proeng.2011.11.2558.

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34

Dolmatov, Dmitry, Dmitriy A. Sednev, and Roman Pinchuk. "The Frequency-Domain Algorithm for Ultrasonic Imaging of Complex-Shaped Objects." Key Engineering Materials 769 (April 2018): 262–68. http://dx.doi.org/10.4028/www.scientific.net/kem.769.262.

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The algorithms based on Synthetic Aperture Focusing Technique are aimed at the determination of the imageries of the flaws in controlled objects. Ultrasonic imaging of complex-shaped objects requires specific algorithms which are able to take into account the complicated character of ultrasonic waves propagation. In this article, we suggested the novel frequency-domain algorithm for ultrasonic imaging of complex-shaped objects. This algorithm is based on Phase –shift migration theory and Stolt transform. The evaluation of suggested technique was done by the application of raw ultrasonic data w

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35

Anderson, John, Tariq Alkhalifah, and Ilya Tsvankin. "Fowler DMO and time migration for transversely isotropic media." GEOPHYSICS 61, no. 3 (1996): 835–45. http://dx.doi.org/10.1190/1.1444008.

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The main advantage of Fowler’s dip‐moveout (DMO) method is the ability to perform velocity analysis along with the DMO removal. This feature of Fowler DMO becomes even more attractive in anisotropic media, where imaging methods are hampered by the difficulty in reconstructing the velocity field from surface data. We have devised a Fowler‐type DMO algorithm for transversely isotropic media using the analytic expression for normal‐moveout velocity. The parameter‐estimation procedure is based on the results of Alkhalifah and Tsvankin showing that in transversely isotropic media with a vertical ax

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36

Yang, Liang, Weidong Yu, Shichao Zheng, and Lei Zhang. "Efficient Bistatic SAR Raw Signal Simulator of Extended Scenes." International Journal of Antennas and Propagation 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/130784.

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Bistatic SAR system is a new mode that allocates the radar transmitter and receiver on different platforms and has more advantages compared to the monostatic case. However, the existing bistatic SAR raw data simulator in the frequency domain can only handle the case of translation invariant system. In this paper, an efficient 2D frequency-domain raw data simulator of extended scenes for bistatic SAR of translation variant system is proposed by a geometric transformation method for the first time, where inverse STOLT interpolation is used to formulate the range migration terms. The presented si

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37

Stolt, Robert H., Alvin K. Benson, and Bruce Gibson. "Seismic Migration: Theory and Practice, Vol. 5 of the Handbook of Geophysical Exploration by Robert H. Stolt and Alvin K. Benson." Journal of the Acoustical Society of America 81, no. 5 (1987): 1651–52. http://dx.doi.org/10.1121/1.395100.

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38

Gruber, Thomas, and Stewart A. Greenhalgh. "Precision analysis of first‐break times in grid models." GEOPHYSICS 63, no. 3 (1998): 1062–65. http://dx.doi.org/10.1190/1.1444384.

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Rectangular grid velocity models and their derivatives are widely used in geophysical inversion techniques. Specifically, seismic tomographic reconstruction techniques, whether they be based on raypath methods (Bregman et al., 1989; Moser, 1991; Schneider et al., 1992; Cao and Greenhalgh, 1993; Zhou, 1993) or full wave equation methods (Vidale, 1990; Qin and Schuster, 1993; Cao and Greenhalgh, 1994) for calculating synthetic arrival times, involve propagation through a grid model. Likewise, migration of seismic reflection data, using asymptotic ray theory or finite difference/pseudospectral me

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39

Carpentier, Stefan F., Heinrich Horstmeyer, Alan G. Green, Joseph Doetsch, and Ilaria Coscia. "Semiautomated suppression of above-surface diffractions in GPR data." GEOPHYSICS 75, no. 6 (2010): J43—J50. http://dx.doi.org/10.1190/1.3497360.

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Diffractions from above-surface objects can be a major problem in the processing and interpretation of ground-penetrating radar (GPR) data. Whereas methods to reduce random and many other types of source-generated noise are available, the efficient suppression of above-surface diffractions (ASDs) continues to be challenging. We have developed a scheme for semiautomatically detecting and suppressing ASDs. Initially, an accurate representation of ASDs is obtained by (1) Stolt [Formula: see text] migrating the GPR data using the air velocity to focus ASDs, (2) multichannel filtering to minimize o

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Qian, Yulei, and Daiyin Zhu. "Focusing of Ultrahigh Resolution Spaceborne Spotlight SAR on Curved Orbit." Electronics 8, no. 6 (2019): 628. http://dx.doi.org/10.3390/electronics8060628.

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Aiming to acquire ultrahigh resolution images, algorithms for spaceborne spotlight synthetic aperture radar (SAR) imaging typically confront challenges of curved orbit and azimuth spectral aliasing. In order to conquer these difficulties, a method is proposed in this paper to obtain ultrahigh resolution spaceborne SAR images on a curved orbit, which is composed of the modified RMA (Range Migration Algorithm) and the modified deramping-based approach. The modified RMA is developed to deal with the effect introduced by a curved orbit and the modified deramping-based approach is utilized to handl

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41

Bano, Maksim. "Q-phase compensation of seismic records in the frequency domain." Bulletin of the Seismological Society of America 86, no. 4 (1996): 1179–86. http://dx.doi.org/10.1785/bssa0860041179.

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Abstract The attenuation process acts as a low-pass filter that attenuates the high frequencies (absorption) of the signal spectrum and also changes the phase of the seismic wavelet (dispersion). Seismic frequency losses are usually recovered according to an appropriate processing technique (such as deterministic or statistical deconvolution methods), while phase distortions are generally disregarded. Therefore, accurate processing of seismic data requires a careful investigation of the relationship between absorption and phase. In this article, a procedure is presented to accomplish this goal

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Burch, Gabriela, and Upali Sarathchandra. "Activities and survival of endophytic bacteria in white clover (Trifolium repensL.)." Canadian Journal of Microbiology 52, no. 9 (2006): 848–56. http://dx.doi.org/10.1139/w06-039.

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In this study, the genera, abundance, and activities of endophytic bacteria in field-grown white clover (Trifolium repens) and the fate of introduced antibiotic-tolerant bacteria in white clover tissues were investigated. Pseudomonas, Pantoea, and Corynebacterium were the most frequently isolated endophytic bacteria genera, whereas Xanthomonas, Microbacterium, and Cellulomonas occurred less frequently. The average bacterial populations in stolons and roots were approximately 100 000 colony-forming units (CFU) (g wet mass)–1. Of the 28 strains tested for activity, none were chitinolytic or able

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Craig Beasley, Walt Lynn, Ken Larne. "Extended Stolt F-K Migration: ABSTRACT." AAPG Bulletin 72 (1988). http://dx.doi.org/10.1306/703c8c63-1707-11d7-8645000102c1865d.

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Yake, Li, and Siu O’ Young. "A Modified Range Migration Algorithm for FMCW SAR Signal Processing." Remote Sensing 8, no. 1 (2019). http://dx.doi.org/10.18282/rs.v6i3.517.

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<p class="AbstractText"><span lang="EN-AU">The range migration algorithm (RMA) is an accurate imaging method for processing synthetic aperture radar (SAR) signals. However, this algorithm requires a big amount of computation when performing Stolt mapping. In high squint and wide beamwidth imaging, this operation also requires big memory size to store the result spectrum after Stolt mapping because the spectrum will be significantly expanded. A modified Stolt mapping that does not expand the signal spectrum while still maintains the processing accuracy is proposed in this paper to i

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Yake, Li, and Siu O’ Young. "A Modified Range Migration Algorithm for FMCW SAR Signal Processing." Remote Sensing 8, no. 1 (2019). http://dx.doi.org/10.18282/rs.v8i1.517.

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<p class="AbstractText"><span lang="EN-AU">The range migration algorithm (RMA) is an accurate imaging method for processing synthetic aperture radar (SAR) signals. However, this algorithm requires a big amount of computation when performing Stolt mapping. In high squint and wide beamwidth imaging, this operation also requires big memory size to store the result spectrum after Stolt mapping because the spectrum will be significantly expanded. A modified Stolt mapping that does not expand the signal spectrum while still maintains the processing accuracy is proposed in this paper to i

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Ray, Arnab K. "Analytical fundamentals of migration in reflection seismics." Open Geosciences 8, no. 1 (2016). http://dx.doi.org/10.1515/geo-2016-0025.

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AbstractWe consider migration in reflection seismics from a completely analytical perspective. We review the basic geometrical ray-path approach to understanding the subject of migration, and discuss the limitations of this method. We stress the importance of the linear differential wave equation in migration. We also review briefly how a wavefield, travelling with a constant velocity, is extrapolated from the differential wave equation, with the aid of Fourier transforms. Then we present a non-numerical treatment by which we derive an asymptotic solution for both the amplitude and the phase o

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Bradshaw, Brian, Kerry Thompson, and Uri Frank. "Distinct mechanisms underlie oral vs aboral regeneration in the cnidarian Hydractinia echinata." eLife 4 (April 17, 2015). http://dx.doi.org/10.7554/elife.05506.

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Cnidarians possess remarkable powers of regeneration, but the cellular and molecular mechanisms underlying this capability are unclear. Studying the hydrozoan Hydractinia echinata we show that a burst of stem cell proliferation occurs following decapitation, forming a blastema at the oral pole within 24 hr. This process is necessary for head regeneration. Knocking down Piwi1, Vasa, Pl10 or Ncol1 expressed by blastema cells inhibited regeneration but not blastema formation. EdU pulse-chase experiments and in vivo tracking of individual transgenic Piwi1+ stem cells showed that the cellular sourc

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"To: “Migration and inversion of seismic data,” by R. H. Stolt and A.B. Weglein which appeared in the December 1985 issue of GEOPHYSICS, p. 2458–2472." GEOPHYSICS 52, no. 10 (1987): 1455. http://dx.doi.org/10.1190/1.1442261.

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