Scale effects of velocity dispersion and attenuation (Q−1) in layered viscoelastic medium

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. T147-T166 ◽  
Author(s):  
Vishal Das ◽  
Tapan Mukerji ◽  
Gary Mavko
Keyword(s):  
Viscoelastic Medium ◽  
Velocity Dispersion ◽  
Scale Effects ◽  
Elastic Case ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Scattering Attenuation ◽  
Layered Viscoelastic Medium ◽  
The Impact ◽  
Dispersion And Attenuation

We have used numerical modeling of normal incidence P-waves in periodic and nonperiodic viscoelastic layered media to help improve understanding of the scale effects of heterogeneity on velocity dispersion and attenuation. The improved understanding of these effects facilitates better interpretation and integration of data acquired at different scales, such as seismic data, well-log data, and laboratory measurements. We developed a direct method for estimating velocity and attenuation for viscoelastic media, the viscoelastic Kennett-Frazer (vKF) method, which is an invariant imbedding (reflectivity) method that uses reflection and transmission transfer functions. The vKF method is used to estimate rigorous dispersion and attenuation curves for periodic and nonperiodic cases. The results from our studies validate and quantify the intuitive qualitative understanding that dispersion and attenuation for a layered viscoelastic medium depend on the ratio of wavelength of the waves ([Formula: see text]) and the spatial period of the medium ([Formula: see text]), similar to the elastic case. We also decoupled the total effective attenuation obtained from the viscoelastic case into scattering attenuation that can be modeled from the elastic case and the intrinsic effective attenuation that is present in addition to the scattering attenuation in the viscoelastic case. The calculated intrinsic effective attenuation curves matched the theoretical values at the ray theory and effective medium theory limits. We derived analytical expressions for the long-wavelength limit of velocity and attenuation in a viscoelastic medium. Our expressions can be used directly for the upscaling of well logs to seismic scale considering viscoelastic effects. The expressions indicate the coupling between effective velocity and effective intrinsic attenuation in the long-wavelength limit. Finally, we use the derived expressions to determine the difference between elastic versus viscoelastic upscaling and to highlight the impact on traveltime and amplitude by properly considering viscoelastic information, especially for quantitative seismic interpretation workflows.

scholarly journals Investigation of the long wavelength limit of soliton self-frequency shift in a silica fiber

2018 ◽  
Vol 26 (15) ◽  
pp. 19637 ◽  
Author(s):  
Bo Li ◽  
Mengran Wang ◽  
Kriti Charan ◽  
Ming-jun Li ◽  
Chris Xu
Keyword(s):  
Frequency Shift ◽  
Silica Fiber ◽  
Long Wavelength ◽  
Wavelength Limit

Stationary charged surface configuration of a conducting liquid in the long-wavelength limit

2008 ◽  
Vol 34 (2) ◽  
pp. 97-99 ◽  
Author(s):  
K. E. Bobrov ◽  
G. Sh. Boltachev ◽  
N. M. Zubarev ◽  
O. V. Zubareva
Keyword(s):  
Charged Surface ◽  
Conducting Liquid ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Surface Configuration

scholarly journals Industrial efficiency analysis based on the spatial panel model

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Xiaobo Yin ◽  
Liyan Guo
Keyword(s):  
Regional Cooperation ◽  
Scale Effects ◽  
Spillover Effects ◽  
Economic Transformation ◽  
Environmental Efficiency ◽  
Green Economy ◽  
Industrial Technology ◽  
High Tech ◽  
Industrial Agglomeration ◽  
The Impact

AbstractHigh-tech industrial agglomeration is conducive to boosting technological progress, promoting industrial structure upgrading and realizing economic transformation, and certainly affects the overall industrial environmental efficiency. However, few recent studies have focused on its impact on industrial environmental efficiency from a green perspective. In the context of promoting the development of green economy, it is of great significance to clarify the links between high-tech industrial agglomeration and industrial environmental efficiency. In this research, we first analyzed the theoretical mechanism of the impact of high-tech industrial agglomeration and its spatial spillover effects on industrial environmental efficiency and then made an empirical analysis based on the panel data of 29 provinces and cities in China from 2003 to 2016. During the research, Super-DEA method, ESDA method and spatial Dubin model are used. The result shows that: (1) There is a significant spatial positive correlation between China's industrial environmental efficiency and high-tech industrial agglomeration; (2) high-tech industrial agglomeration has improved the local industrial productivity and industrial technology level through scale effects and technical effects, which has accordingly significantly enhanced the corresponding environmental efficiency; (3) through the association of regional industries, the cross-regional cooperation of enterprises and the formation of innovation networks, high-tech industrial agglomeration promotes the spillover of knowledge and technology among regions, improves the level of industrial technology in neighboring regions, and enhances the industrial environmental efficiency in neighboring regions. All these three is helpful to re-evaluate the development mode of high-tech industry agglomeration and to formulate relevant government policies.

Wave Impact Loads on the Bottom of Flat Decks

2021 ◽  
Author(s):  
Daniel de Oliveira Costa ◽  
Julia Araújo Perim ◽  
Bruno Guedes Camargo ◽  
Joel Sena Sales Junior ◽  
Antonio Carlos Fernandes ◽  
...  
Keyword(s):  
Scale Effects ◽  
Offshore Structures ◽  
Model Tests ◽  
Analytical Models ◽  
Navier Stokes ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Channel ◽  
Waves And Currents ◽  
The Impact

Abstract Slamming events due to wave impact on the underside of decks might lead to severe and potentially harmful local and/or global loads in offshore structures. The strong nonlinearities during the impact require a robust method for accessing the loads and hinder the use of analytical models. The use of computation fluid dynamics (CFD) is an interesting alternative to estimate the impact loads, but validation through experimental data is still essential. The present work focuses on a flat-bottomed model fixed over the mean free surface level submitted to regular incoming waves. The proposal is to reproduce previous studies through CFD and model tests in a different reduced scale to provide extra validation and to identify possible non-potential scale effects such as air compressibility. Numerical simulations are performed in both experiments’ scales. The numerical analysis is performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to build spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. The new model tests were performed at the wave channel of the Laboratory of Waves and Currents (LOC/COPPE – UFRJ), at the Federal University of Rio de Janeiro.

scholarly journals Thermodynamic, structural, transport and surface properties of Pb-Tl liquid alloy

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 100-113 ◽  
Author(s):  
SK Yadav ◽  
LN Jha ◽  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Surface Concentration ◽  
Heat Of Formation ◽  
Concentration Fluctuation ◽  
Heat Of Mixing ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Experimental Values

Thermodynamic properties, such as free energy of mixing, heat of mixing, entropy of mixing, activities and the microscopic structural properties, such as concentration fluctuation in long-wavelength limit and chemical short-range order parameter of Pb-Tl liquid alloy at 773 K have been studied on the basis of regular associated solution model. We have estimated the mole fractions of the complex and the unassociated atoms assuming the existence of  complex as energetically favoured in the liquid state. The compositional contributions of the heat of mixing of the species Pb and Tl and the heat of formation of the compound to the net enthalpy change have also been studied. The transport properties such as, viscosity and the ratio of mutual and intrinsic coefficients have been studied using different approaches. The surface concentration of Tl atoms has been computed and it has been employed to calculate the surface tension of Pb-Tl liquid alloy. Both the theoretical and the experimental values of the concentration fluctuation in long-wavelength limit are found to be less than the ideal value, revealing that the concerned system is hetero-coordinating in nature. The interaction energies are found to be temperature dependent and respective alloy is found to be weakly interacting system. BIBECHANA 13 (2016) 100-113

The Long-wavelength Limit of the Dielectric Function for Dense Plasmas

1999 ◽  
Vol 39 (1-2) ◽  
pp. 77-80 ◽  
Author(s):  
H. Reinholz ◽  
R. Redmer ◽  
G. Röpke ◽  
A. Wierling
Keyword(s):  
Dielectric Function ◽  
Dense Plasmas ◽  
Long Wavelength ◽  
Wavelength Limit
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