A novel approximate formula on AVAZ of reflection and transmission qP in TTI media

2020 ◽  
Vol 192 ◽  
pp. 107280
Author(s):  
Pan Wang ◽  
Zhenan Yao ◽  
Suping Peng ◽  
Shunqiang Hu
Keyword(s):  
Approximate Formula ◽  
Reflection And Transmission ◽  
Tti Media

THE REFLECTION OF WAVES IN A GENERALIZED EPSTEIN PROFILE

1965 ◽  
Vol 43 (5) ◽  
pp. 921-934 ◽  
Author(s):  
R. Burman ◽  
R. N. Gould
Keyword(s):  
Refractive Index ◽  
Wave Equation ◽  
Reflection Coefficient ◽  
Approximate Formula ◽  
Reflection And Transmission Coefficients ◽  
Stratified Medium ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Special Case ◽  
Reflection Of Waves

Epstein (1930) and Rawer (1939) studied the reflection of waves in a stratified medium by transforming the hypergeometric equation into the wave equation. A particular case of the Epstein profile is a symmetrical layer. Considerable attention has been given in the literature to this case as well as to symmetrical layers with certain other profiles of the refractive index. In the present paper a generalized Epstein profile is considered and the reflection and transmission coefficients are obtained. The special case in which the refractive index tends to the same constant value on either side of a layer is then discussed. The symmetrical Epstein profile is a special case of this layer which, in general, is asymmetrical. Particular attention is given to a layer differing only slightly from the symmetrical Epstein layer, a simple approximate formula for the reflection coefficient being derived.

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 398-399
Author(s):  
M. Gajdardziska-Josifovska
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Reflection And Transmission ◽  
Experimental Diffraction Pattern ◽  
Surface Resonance ◽  
Reconstructed Surfaces ◽  
Reflection Electron Microscopy ◽  
Convergent Beam

Parabolas have been observed in the reflection high-energy electron diffraction (RHEED) patterns from surfaces of single crystals since the early thirties. In the last decade there has been a revival of attempts to elucidate the origin of these surface parabolas. The renewed interest stems from the need to understand the connection between the parabolas and the surface resonance (channeling) condition, the latter being routinely used to obtain higher intensity in reflection electron microscopy (REM) images of surfaces. Several rather diverging descriptions have been proposed to explain the parabolas in the reflection and transmission Kikuchi patterns. Recently we have developed an unifying general treatment in which the parabolas are shown to be K-lines of two-dimensional lattices. Here we want to review the main features of this description and present an experimental diffraction pattern from a 30° MgO (111) surface which displays parabolas that can be attributed to the surface reconstruction.

Reverse time migration in tilted transversely isotropic media

2020 ◽  
Vol 38 (2) ◽  
Author(s):  
Razec Cezar Sampaio Pinto da Silva Torres ◽  
Leandro Di Bartolo
Keyword(s):  
Seismic Anisotropy ◽  
Synthetic Data ◽  
Transversely Isotropic ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Computer Clusters ◽  
Time Migration ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
Tti Media

ABSTRACT. Reverse time migration (RTM) is one of the most powerful methods used to generate images of the subsurface. The RTM was proposed in the early 1980s, but only recently it has been routinely used in exploratory projects involving complex geology – Brazilian pre-salt, for example. Because the method uses the two-way wave equation, RTM is able to correctly image any kind of geological environment (simple or complex), including those with anisotropy. On the other hand, RTM is computationally expensive and requires the use of computer clusters. This paper proposes to investigate the influence of anisotropy on seismic imaging through the application of RTM for tilted transversely isotropic (TTI) media in pre-stack synthetic data. This work presents in detail how to implement RTM for TTI media, addressing the main issues and specific details, e.g., the computational resources required. A couple of simple models results are presented, including the application to a BP TTI 2007 benchmark model.Keywords: finite differences, wave numerical modeling, seismic anisotropy. Migração reversa no tempo em meios transversalmente isotrópicos inclinadosRESUMO. A migração reversa no tempo (RTM) é um dos mais poderosos métodos utilizados para gerar imagens da subsuperfície. A RTM foi proposta no início da década de 80, mas apenas recentemente tem sido rotineiramente utilizada em projetos exploratórios envolvendo geologia complexa, em especial no pré-sal brasileiro. Por ser um método que utiliza a equação completa da onda, qualquer configuração do meio geológico pode ser corretamente tratada, em especial na presença de anisotropia. Por outro lado, a RTM é dispendiosa computacionalmente e requer o uso de clusters de computadores por parte da indústria. Este artigo apresenta em detalhes uma implementação da RTM para meios transversalmente isotrópicos inclinados (TTI), abordando as principais dificuldades na sua implementação, além dos recursos computacionais exigidos. O algoritmo desenvolvido é aplicado a casos simples e a um benchmark padrão, conhecido como BP TTI 2007.Palavras-chave: diferenças finitas, modelagem numérica de ondas, anisotropia sísmica.

scholarly journals Influence of Rugate Filters on the Spectral Manifestation of Tamm Plasmon Polaritons

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1282
Author(s):  
Victor Reshetnyak ◽  
Igor Pinkevych ◽  
Timothy Bunning ◽  
Dean Evans
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
External Medium ◽  
Metal Layer ◽  
Refractive Index Profile ◽  
Spectral Position ◽  
Index Profile ◽  
Reflection And Transmission ◽  
Rugate Filter ◽  
Plasmon Polaritons

This study theoretically investigated light reflection and transmission in a system composed of a thin metal layer (Ag) adjacent to a rugate filter (RF) having a harmonic refractive index profile. Narrow dips in reflectance and peaks in transmittance in the RF band gap were obtained due to the excitation of a Tamm plasmon polariton (TPP) at the Ag–RF interface. It is shown that the spectral position and magnitude of the TPP dips/peaks in the RF band gap depend on the harmonic profile parameters of the RF refractive index, the metal layer thickness, and the external medium refractive index. The obtained dependences for reflectance and transmittance allow selecting parameters of the system which can be optimized for various applications.

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