Modeling and imaging with the scalar generalized‐screen algorithms in isotropic media

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1551-1568 ◽  
Author(s):  
Jéro⁁me H. Le Rousseau ◽  
Maarten V. de Hoop
Keyword(s):  
Heterogeneous Media ◽  
Fourier Method ◽  
Numerical Algorithms ◽  
Velocity Model ◽  
The Family ◽  
Isotropic Media ◽  
And Migration ◽  
The One ◽  
Lateral Variations ◽  
Synthetic Models

The phase‐screen and the split‐step Fourier methods, which allow modeling and migration in laterally heterogeneous media, are generalized here so as to increase their accuracies for media with large and rapid lateral variations. The medium is defined in terms of a background medium and a perturbation. Such a contrast formulation induces a series expansion of the vertical slowness in which we recognize the first term as the split‐step Fourier approximation and the addition of higher‐order terms of the expansion increases the accuracy. Employing this expansion in the one‐way scalar propagator yields the scalar one‐way generalized‐screen propagator. We also introduce a generalized‐screen representation of the reflection operator. The interaction between the upgoing and downgoing fields is taken into account by a Bremmer series. These results are then cast into numerical algorithms. We analyze the accuracy of the generalized‐screen method in complex structures using synthetic models that exhibit significant multipathing: the IFP 2‐D Marmousi model and the SEG‐EAGE 3‐D salt model. As compared with the split‐step Fourier method, in the presence of lateral medium variations, the generalized‐screen methods exhibit an increased accuracy at wider angles of propagation and scattering. As a result, in the process of migration, we can choose a member of the family of our generalized‐screen algorithms in accordance with the complexity of the medium (velocity model).

Multiples: Signal or noise?

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. V283-V302 ◽  
Author(s):  
Arthur B. Weglein
Keyword(s):  
High Frequency ◽  
Heterogeneous Media ◽  
Velocity Model ◽  
Structural Determination ◽  
Subsurface Structure ◽  
Amplitude Analysis ◽  
Migration Method ◽  
And Migration ◽  
And Inversion

Migration and migration inversion are the seismic processing methods for structural determination and subsequent amplitude analysis, respectively. To date, the most well-founded and physically interpretable migration method is based on predicting a coincident source and receiver experiment at depth at time equals zero. We have extended that migration method for heterogeneous media and to accommodate two-way propagation in a local sense at every point from the source to the target reflector and back from the reflector to the receiver and in a global sense, separately for each of the two legs from the source to the reflector and from the reflector to the receiver. That provides the first migration method that avoids high-frequency assumptions in the imaging principle and how it is implemented, and hence, it is equally effective at all frequencies at the target or reservoir. This advance for two-way wave propagation migration then provides a tool to quantitatively, unambiguously, and definitively define the role of primaries and multiples in migration. Our conclusion was that with data consisting of primaries and multiples, for an accurate discontinuous velocity model, only primaries contribute to migration with the same image and inversion results independent of whether multiples are kept or removed. However, for a smooth and continuous velocity model (i.e., generally assumed in practice), every multiple will result in a false, misleading, and potentially injurious subsurface image and hence must be removed before migration. In practice, we migrate with a smooth velocity model, and hence multiples must be removed. When the collection of primaries is incomplete, a multiple can be used to provide an approximate image of an unrecorded primary. However, it is always the migration of primaries that provides subsurface structure and amplitude information.

Scalar generalized‐screen algorithms in transversely isotropic media with a vertical symmetry axis

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1538-1550 ◽  
Author(s):  
Jéro⁁me H. Le Rousseau ◽  
Maarten V. de Hoop
Keyword(s):  
Symmetry Axis ◽  
Complex Structure ◽  
Numerical Algorithms ◽  
Transversely Isotropic ◽  
Isotropic Case ◽  
Polarization Angle ◽  
Screen Method ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
The One

The scalar generalized‐screen method in isotropic media is extended here to transversely isotropic media with a vertical symmetry axis (VTI). Although wave propagation in a transversely isotropic medium is essentially elastic, we use an equivalent “acoustic” system of equations for the qP‐waves which we prove to be accurate for both the dispersion relation and the polarization angle in the case of “mild” anisotropy. The enhanced accuracy of the generalized‐screen method as compared to the split‐step Fourier methods allows the extension to VTI media. The generalized‐screen expansion of the one‐way propagator follows closely the method used in the isotropic case. The medium is defined in terms of a background and a perturbation. The generalized‐screen expansion of the vertical slowness is based upon an expansion of the medium parameters simultaneously into magnitude and smoothness of variation. We cast the theory into numerical algorithms, and assess the accuracy of the generalized‐screen method in a particular VTI medium with complex structure (the BP Amoco Valhall model) in which multipathing is significant.

Kirchhoff migration and velocity analysis for converted and nonconverted waves in anisotropic media

Geophysics ◽  
1993 ◽  
Vol 58 (2) ◽  
pp. 265-276 ◽  
Author(s):  
Arcangelo G. Sena ◽  
M. Nafi Toksöz
Keyword(s):  
Anisotropic Media ◽  
Velocity Model ◽  
Velocity Analysis ◽  
Converted Wave ◽  
Anisotropic Models ◽  
Kirchhoff Migration ◽  
Analysis Technique ◽  
Analysis Scheme ◽  
Isotropic Media ◽  
And Migration

We develop asymptotic expressions and outline a procedure to perform Kirchhoff migration in anisotropic media. This technique is based on a new Green’s tensor representation for azimuthally isotropic media obtained by using analytical forms for the ray amplitudes and traveltimes. Since in real applications the usage of general anisotropy in a migration scheme will be limited by the availability and reliability of the velocity model considered, we also develop a new anisotropic velocity analysis scheme to generate realistic anisotropic models for migration in azimuthally isotropic media for nonconverted and converted qP-qSV waves. This velocity analysis technique is based on nonhyperbolic traveltime‐offset formulas explicitly given in terms of the five elastic constants of azimuthal isotropy. The imaging technique is applied to nonconverted‐as well as converted‐wave surface seismic data. In both cases the method provides accurate images of the subsurface. Even with a weak to moderate percentage of anisotropy, we show that an isotropic migration algorithm cannot properly image the subsurface. This paper provides new nonconventional techniques for the velocity analysis and migration in anisotropic media and shows the feasibility of exploiting converted and nonconverted waves.

scholarly journals The Significance of Geographical Factors in Genealogy to Language Research——Taking Liao’s Audio-visual Genealogy as an Example

2020 ◽  
Vol 4 (10) ◽  
Author(s):  
Jiajia Xi
Keyword(s):  
Development Trend ◽  
Geographical Information ◽  
Evolution Of Language ◽  
Language Research ◽  
The Family ◽  
Language Behavior ◽  
Formation And Evolution ◽  
And Migration ◽  
The One ◽  
The Development Trend

The geographical information reflected in a traditional genealogy mainly has two aspects. On the one hand, it is the administrative division, human geography, and other general environmental conditions of the ethnic group. On the other hand, it points to the specific origin and migration of family members in the family tree. In addition to affecting the formation and evolution of language, these factors will also affect the development trend of language behavior by promoting the psychology of people's geographic identity. From these data, we find that geographic factors in the genealogy have a non-negligible relationship with the geographical spread of the language of the genealogy.

Murder with Impunity: The Construction of Arab Masculinities and Honor Crimes

1970 ◽  
pp. 38-45
Author(s):  
May Abu Jaber
Keyword(s):  
Violence Against Women ◽  
Social Boundaries ◽  
Religious Institutions ◽  
The Social ◽  
The Family ◽  
The Media ◽  
The One ◽  
Male Authority ◽  
Cultural Networks ◽  
Gender Specific

Violence against women (VAW) continues to exist as a pervasive, structural,systematic, and institutionalized violation of women’s basic human rights (UNDivision of Advancement for Women, 2006). It cuts across the boundaries of age, race, class, education, and religion which affect women of all ages and all backgrounds in every corner of the world. Such violence is used to control and subjugate women by instilling a sense of insecurity that keeps them “bound to the home, economically exploited and socially suppressed” (Mathu, 2008, p. 65). It is estimated that one out of every five women worldwide will be abused during her lifetime with rates reaching up to 70 percent in some countries (WHO, 2005). Whether this abuse is perpetrated by the state and its agents, by family members, or even by strangers, VAW is closely related to the regulation of sexuality in a gender specific (patriarchal) manner. This regulation is, on the one hand, maintained through the implementation of strict cultural, communal, and religious norms, and on the other hand, through particular legal measures that sustain these norms. Therefore, religious institutions, the media, the family/tribe, cultural networks, and the legal system continually disciplinewomen’s sexuality and punish those women (and in some instances men) who have transgressed or allegedly contravened the social boundaries of ‘appropriateness’ as delineated by each society. Such women/men may include lesbians/gays, women who appear ‘too masculine’ or men who appear ‘too feminine,’ women who try to exercise their rights freely or men who do not assert their rights as ‘real men’ should, women/men who have been sexually assaulted or raped, and women/men who challenge male/older male authority.

Preface to the special issue, CMAM 2011, no. 3.

2011 ◽  
Vol 11 (3) ◽  
pp. 272
Author(s):  
Ivan Gavrilyuk ◽  
Boris Khoromskij ◽  
Eugene Tyrtyshnikov
Keyword(s):  
Separation Of Variables ◽  
Numerical Algorithms ◽  
Multilevel Methods ◽  
High Dimensional ◽  
Special Issue ◽  
High Dimensions ◽  
Guiding Principle ◽  
Tensor Methods ◽  
Closed World ◽  
The One

Abstract In the recent years, multidimensional numerical simulations with tensor-structured data formats have been recognized as the basic concept for breaking the "curse of dimensionality". Modern applications of tensor methods include the challenging high-dimensional problems of material sciences, bio-science, stochastic modeling, signal processing, machine learning, and data mining, financial mathematics, etc. The guiding principle of the tensor methods is an approximation of multivariate functions and operators with some separation of variables to keep the computational process in a low parametric tensor-structured manifold. Tensors structures had been wildly used as models of data and discussed in the contexts of differential geometry, mechanics, algebraic geometry, data analysis etc. before tensor methods recently have penetrated into numerical computations. On the one hand, the existing tensor representation formats remained to be of a limited use in many high-dimensional problems because of lack of sufficiently reliable and fast software. On the other hand, for moderate dimensional problems (e.g. in "ab-initio" quantum chemistry) as well as for selected model problems of very high dimensions, the application of traditional canonical and Tucker formats in combination with the ideas of multilevel methods has led to the new efficient algorithms. The recent progress in tensor numerical methods is achieved with new representation formats now known as "tensor-train representations" and "hierarchical Tucker representations". Note that the formats themselves could have been picked up earlier in the literature on the modeling of quantum systems. Until 2009 they lived in a closed world of those quantum theory publications and never trespassed the territory of numerical analysis. The tremendous progress during the very recent years shows the new tensor tools in various applications and in the development of these tools and study of their approximation and algebraic properties. This special issue treats tensors as a base for efficient numerical algorithms in various modern applications and with special emphases on the new representation formats.

scholarly journals Personality and Dementia: an Approach to Differential Profile of the Caregiver

2011 ◽  
Vol 1 (3) ◽  
pp. 85-94
Author(s):  
Elena de Andrés-Jiménez ◽  
Rosa Mª Limiñana-Gras ◽  
Encarna Fernández-Ros
Keyword(s):  
Relevant Information ◽  
Personality Profile ◽  
Family Carers ◽  
Psychological Variables ◽  
People With Dementia ◽  
The Family ◽  
Study Population ◽  
The One ◽  
The Impact

The aim of this study is to determine the existence of a characteristic personality profile of family carers of people with dementia. The correct knowledge and use of psychological variables which affect the carer, helps to promote appropriate actions to mitigate the impact of care and improve the carer’s quality of life and likewise the one of the person cared for. The study population consists of 69 family carers of people with dementia, members of various associations and care centers. The results allow us to identify a characteristic personality profile for these carers and it reveals a specific psychological working in this sample, although we cannot directly relate it with the tasks of caring for people with this disease, this profile gives us very relevant information to pay more attention to the needs of this group. Moreover, the analysis of personality styles depends on the sex of the family carer, showing, once again, that the woman is in a situation of most vulnerability.

scholarly journals The Image of the Family and Family Home in Małgorzata Musierowicz’s Series of Novels, and the Stereotype of the Family in Contemporary Polish Society

2021 ◽  
Author(s):  
Joanna Senderska ◽  
Iwona Mityk ◽  
Ewa Piotrowska-Oberda
Keyword(s):  
Social Consciousness ◽  
Traditional Family ◽  
Patriarchal Family ◽  
Family Model ◽  
The Family ◽  
Language Data ◽  
Polish Society ◽  
Family Home ◽  
The One ◽  
Over 40 Years

AbstractThe article discusses the image of the family and the family home in a series of novels for young people by the popular Polish writer Małgorzata Musierowicz in the context of literary conventions and stereotypes about the family in contemporary Polish society. The novels, which cover a period of over 40 years, generally fit contemporary Polish realities; however, the didactic function of the novels results in the author creating an idealized image of the Polish intellectual family, filling the readers with optimism. The picture created by the writer, on the one hand, fits perfectly into the stereotype of the family, which is one of the values highly esteemed by Poles. On the other hand, it adapts to the conventions of novels for girls. In this article, the stereotype of the family is reconstructed on the basis of language data and surveys. We present the meanings and contexts of family as a noun and family as an adjective. We also present the results of our survey, the aim of which was to determine an essence of a stereotypical family and how the traditional family model is comprehended by respondents coming from various groups. We also present the respondents’ attitude to the patriarchal family model and the division of roles into male and female. In our opinion, the correspondence between the family picture created in the novels and the image of the family operating in social consciousness is the reason for the popularity of the series.

scholarly journals Two Separate Cases: Complex Chromosomal Abnormality Involving Three Chromosomes and Small Supernumerary Marker Chromosome in Patients with Impaired Reproductive Function

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1511
Author(s):  
Tatyana V. Karamysheva ◽  
Tatyana A. Gayner ◽  
Vladimir V. Muzyka ◽  
Konstantin E. Orishchenko ◽  
Nikolay B. Rubtsov
Keyword(s):  
Genetic Counseling ◽  
Chromosome Rearrangement ◽  
Marker Chromosome ◽  
Reproductive Function ◽  
Small Supernumerary Marker Chromosome ◽  
Comprehensive Chromosome Screening ◽  
The Family ◽  
Multicolor Banding ◽  
The One

For medical genetic counseling, estimating the chance of a child being born with chromosome abnormality is crucially important. Cytogenetic diagnostics of parents with a balanced karyotype are a special case. Such chromosome rearrangements cannot be detected with comprehensive chromosome screening. In the current paper, we consider chromosome diagnostics in two cases of chromosome rearrangement in patients with balanced karyotype and provide the results of a detailed analysis of complex chromosomal rearrangement (CCR) involving three chromosomes and a small supernumerary marker chromosome (sSMC) in a patient with impaired reproductive function. The application of fluorescent in situ hybridization, microdissection, and multicolor banding allows for describing analyzed karyotypes in detail. In the case of a CCR, such as the one described here, the probability of gamete formation with a karyotype, showing a balance of chromosome regions, is extremely low. Recommendation for the family in genetic counseling should take into account the obtained result. In the case of an sSMC, it is critically important to identify the original chromosome from which the sSMC has been derived, even if the euchromatin material is absent. Finally, we present our view on the optimal strategy of identifying and describing sSMCs, namely the production of a microdissectional DNA probe from the sSMC combined with a consequent reverse painting.

Quasi‐shear waves in inhomogeneous weakly anisotropic media by the quasi‐isotropic approach: A model study

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 308-319 ◽  
Author(s):  
Ivan Pšenčík ◽  
Joe A. Dellinger
Keyword(s):  
Order Approximation ◽  
Anisotropic Media ◽  
Ray Method ◽  
Weak Anisotropy ◽  
S Waves ◽  
Model Study ◽  
Arbitrary Strength ◽  
Isotropic Media ◽  
Synthetic Models ◽  
Ray Methods

In inhomogeneous isotropic regions, S-waves can be modeled using the ray method for isotropic media. In inhomogeneous strongly anisotropic regions, the independently propagating qS1- and qS2-waves can similarly be modeled using the ray method for anisotropic media. The latter method does not work properly in inhomogenous weakly anisotropic regions, however, where the split qS-waves couple. The zeroth‐order approximation of the quasi‐isotropic (QI) approach was designed for just such inhomogeneous weakly anisotropic media, for which neither the ray method for isotropic nor anisotropic media applies. We test the ranges of validity of these three methods using two simple synthetic models. Our results show that the QI approach more than spans the gap between the ray methods: it can be used in isotropic regions (where it reduces to the ray method for isotropic media), in regions of weak anisotropy (where the ray method for anisotropic media does not work properly), and even in regions of moderately strong anisotropy (in which the qS-waves decouple and thus could be modeled using the ray method for anisotropic media). A modeling program that switches between these three methods as necessary should be valid for arbitrary‐strength anisotropy.

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