The Site Effect Analysis of Semi-Cylindrical Canyons and Soft Alluvial Basins by H/V Spectral Ratio

2012 ◽  
Vol 204-208 ◽  
pp. 2465-2468
Author(s):  
Cheng Chih Chen ◽  
Wen Shinn Shyu ◽  
Chau Shioung Yeh ◽  
Cheh Shyh Ting
Keyword(s):  
Frequency Domain ◽  
Earthquake Engineering ◽  
Scattering Problem ◽  
Expansion Method ◽  
Spectral Ratio ◽  
Site Effect ◽  
Scattering Problems ◽  
Effect Analysis ◽  
Wave Amplification ◽  
Seismic Wave Amplification

The source, path and site effects are the main causes for ground motions. Soft alluvial basins especially result in seismic wave amplification as the site effect. Irregular alluvial basins and canyons in this study are semi-cylindrical for simplifying analysis. To deal with the scattering problems in frequency domain, Yeh et al. have gained positive outcomes by using a hybrid method which combined finite elements and the series expansion method to effectively solve the scattering problem in the irregular basins. These displacements derived from the frequency domain are computed with the H/V ratio to estimate the site effect. As the site effect is crucial in earthquake engineering, this study may serve as a quantitative contribution towards the amplified effect in alluvial basins and canyons. It can also simulate the effects of different incident angles on the H/V ratio.

Horizontal-to-Vertical Spectral Ratio (HVSR) IRIS Station Toolbox

2020 ◽  
Vol 91 (6) ◽  
pp. 3539-3549
Author(s):  
Manochehr Bahavar ◽  
Zack J. Spica ◽  
Francisco J. Sánchez-Sesma ◽  
Chad Trabant ◽  
Arash Zandieh ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Spectral Ratio ◽  
Site Effect ◽  
Predominant Frequency ◽  
Density Estimates ◽  
Effect Analysis ◽  
Seismic Stations ◽  
Arctic Regions ◽  
Power Spectral ◽  
The Many

Abstract The horizontal-to-vertical spectral ratio (HVSR) for seismic ambient noise is a popular method that can be used to estimate the predominant frequency at a given site. In this article, we introduce the Incorporated Research Institutions for Seismology (IRIS) Data Management Center’s (DMC’s) openly available HVSR station toolbox. These tools offer a variety of ways to compute the spectral ratio by providing different averaging routines. The options range from the simple average of spectral ratios to the ratio of spectral averages. Computations take advantage of the available power spectral density estimates of ambient noise for the seismic stations, and they can be used to estimate the predominant frequency of the many three-component seismic stations available from the IRIS DMC. Furthermore, to facilitate the identification of the peaks in HVSR profiles for the assessment of the predominant frequency of station sites, the toolbox can also process the results of HVSR analysis to detect and rank HVSR peaks. To highlight the toolbox capabilities, three different examples of possible use of this toolbox for routine site-effect analysis are discussed: (1) site effects related to thawing in Arctic regions, (2) ground-motion amplification in urban area, and (3) estimation of station VS30.

Algorithms for solving scattering problems for the Manakov model of nonlinear Schrödinger equations

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Leonid L. Frumin
Keyword(s):  
Scattering Problem ◽  
Inverse Scattering Problem ◽  
Numerical Algorithms ◽  
Scattering Problems ◽  
Block Matrices ◽  
Nonlinear Schrödinger ◽  
Direct Scattering ◽  
Vector Case ◽  
Manakov Model ◽  
Vector Variant

AbstractWe introduce numerical algorithms for solving the inverse and direct scattering problems for the Manakov model of vector nonlinear Schrödinger equation. We have found an algebraic group of 4-block matrices with off-diagonal blocks consisting of special vector-like matrices for generalizing the scalar problem’s efficient numerical algorithms to the vector case. The inversion of block matrices of the discretized system of Gelfand–Levitan–Marchenko integral equations solves the inverse scattering problem using the vector variant the Toeplitz Inner Bordering algorithm of Levinson’s type. The reversal of steps of the inverse problem algorithm gives the solution of the direct scattering problem. Numerical tests confirm the proposed vector algorithms’ efficiency and stability. We also present an example of the algorithms’ application to simulate the Manakov vector solitons’ collision.

scholarly journals Convergence of the uniaxial PML method for time-domain electromagnetic scattering problems

2021 ◽  
Author(s):  
Changkun Wei ◽  
Jiaqing Yang ◽  
Bo Zhang
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Scattering Problems ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
Time Domain Electromagnetic ◽  
Numer Anal ◽  
The Time Domain

In this paper, we propose and study the uniaxial perfectly matched layer (PML) method for three-dimensional time-domain electromagnetic scattering problems, which has a great advantage over the spherical one in dealing with problems involving anisotropic scatterers. The truncated uniaxial PML problem is proved to be well-posed and stable, based on the Laplace transform technique and the energy method. Moreover, the $L^2$-norm and $L^{\infty}$-norm error estimates in time are given between the solutions of the original scattering problem and the truncated PML problem, leading to the exponential convergence of the time-domain uniaxial PML method in terms of the thickness and absorbing parameters of the PML layer. The proof depends on the error analysis between the EtM operators for the original scattering problem and the truncated PML problem, which is different from our previous work (SIAM J. Numer. Anal. 58(3) (2020), 1918-1940).

Wave Problems for Repetitive Structures and Symplectic Mathematics

1992 ◽  
Vol 206 (6) ◽  
pp. 371-379 ◽  
Author(s):  
W X Zhong ◽  
F W Williams
Keyword(s):  
Wave Scattering ◽  
Power Flow ◽  
Turbine Blades ◽  
Expansion Method ◽  
Space Structures ◽  
Scattering Problems ◽  
Symplectic Matrix ◽  
Conservation Result ◽  
Wave Problems ◽  
Chain Type

Based on the analogy between structural mechanics and optimal control theory, the eigensolutions of a symplectic matrix, the adjoint symplectic ortho-normalization relation and the eigenvector expansion method are introduced into the wave propagation theory for sub-structural chain-type structures, such as space structures, composite material and turbine blades. The positive and reverse algebraic Riccati equations are derived, for which the solution matrices are closely related to the power flow along the sub-structural chain. The power flow orthogonality relation for various eigenvectors is proved, and the energy conservation result is also proved for wave scattering problems.

Ground Motion Analysis in Nonlinear Soil Site with Random Media

2011 ◽  
Vol 368-373 ◽  
pp. 920-925 ◽  
Author(s):  
Yuan Chen ◽  
Jie Li
Keyword(s):  
Random Media ◽  
Site Response ◽  
Scattering Problem ◽  
Expansion Method ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Orthogonal Expansion ◽  
Element Analysis ◽  
Analytical Methodology ◽  
Soil Site

In this article,by incorporating equivalent linearization method and the orthogonal expansion method into the wave finite element analysis of scattering problem, an analytical methodology for the evaluation of seismic response of nonlinear soil site with uncertain properties is proposed . Example is given to show the applicability of the methodology. The results show that the randomness of the site media has important effect on seismic site response , the randomness has greater influence on the variation of accelerations than on displacements. The coupling of the nonlinearity and the randomness of soil enhances the effect of randomness on the soil site.

Robust measurements of corner frequency, t* and site effect: the iterative cluster event method

2020 ◽  
Author(s):  
Pei-Ru Jian ◽  
Ban-Yuan Kuo
Keyword(s):  
Body Wave ◽  
Wave Spectrum ◽  
Chemical Properties ◽  
Spectral Ratio ◽  
Site Effect ◽  
Seismic Attenuation ◽  
Corner Frequency ◽  
P Waves ◽  
Robust Measurements ◽  
The Stability

<p>Seismic attenuation accompanying the velocity structures demonstrates the variations of the physical and chemical properties of the earth. The t* measurement using the seismic body wave spectrum, however, typically encounters the trade-off of corner frequency, t*, and site effect. Ko et al, [2012] proposed the cluster event method (CEM) that reduced the model parameter numbers by grouping the spatial-closed enough events for those traveling to each station along the adjacent paths and sharing one t*. Yet, the site effects among different stations collected in the same cluster bring the challenges on fitting all spectrum. We adapt the cluster strategy to group multiple nearby events recorded by one station only. Moreover, the new iterative CEM algorithm includes both the spectrum and spectral ratio data which provide constraints on seismic moments and corner frequencies of each earthquake inside the cluster, respectively. The final t* and corner frequencies are determined again by including the side effects which are averaging from spectrum residuals in the initial CEM stage. We applied the iterative CEM for earthquakes recorded at dense deployed F-net and Hi-net by NIED in the Tohoku area, Japan. The multitaper spectrums are retrieved from direct P waves with coda wavetrains tapered. Combining the spectral ratio and spectrum data with proper weightings, our new approach increases the stability of t* measurements contributed from better constrains on the corner frequency estimations.</p>

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