scholarly journals Randomly distributed unit sources to enhance optimization in tsunami waveform inversion

2014 ◽  
Vol 2 (5) ◽  
pp. 3659-3682
Author(s):  
I. E. Mulia ◽  
T. Asano
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Surface Deformation ◽  
Waveform Inversion ◽  
Sea Surface ◽  
Tsunami Source ◽  
Unknown Parameters ◽  
Tsunami Waveform Inversion ◽  
Tsunami Waveform

Abstract. Determination of sea surface deformation generated by earthquakes is crucial to the success of tsunami modeling. Using waveforms recorded at measurement stations and assuming that the rupture velocity is much faster than the tsunami wave celerity, sea surface deformation caused by a tsunamigenic earthquake can be inferred through an inversion operation using the Green's function technique. However, this inversion method for tsunami waveforms possesses a limitation, in that the inverse matrix does not always exist because of the non-uniqueness of the solution. In addition to the large number of unknown parameters, which might produce many local optima on the misfit function measure, the search towards optimality is confined by the uniform distance of unit sources used in the regular Green's function. This study proposes a new method to both optimize the determination of the unknown parameters and introduce a global optimization method for tsunami waveform inversion. The method has been tested using an artificial tsunami source with real bathymetry data. A significant improvement is achieved by stochastically searching for an optimal distribution of unit source locations prior to the inversion.

scholarly journals Randomly distributed unit sources to enhance optimization in tsunami waveform inversion

2015 ◽  
Vol 15 (1) ◽  
pp. 187-196 ◽  
Author(s):  
I. E. Mulia ◽  
T. Asano
Keyword(s):  
Waveform Inversion ◽  
Optimal Solution ◽  
Optimization Method ◽  
Pattern Search ◽  
Tsunami Source ◽  
Function Technique ◽  
Unknown Parameters ◽  
Tsunami Waveform Inversion ◽  
Comparison Results ◽  
Tsunami Waveform

Abstract. In tsunami waveform inversion using the conventional Green's function technique, an optimal solution is sometimes difficult to obtain because of various factors. This study proposes a new method to both optimize the determination of the unknown parameters and introduce a global optimization method for tsunami waveform inversion. We utilize a genetic algorithm that further enhanced by a pattern search method to find an optimal distribution of unit source locations prior to the inversion. Unlike the conventional method that characterized by equidistant unit sources, our method generates a random spatial distribution of unit sources inside the inverse region. This leads to a better approximation of the initial profile of a tsunami. The method has been tested using an artificial tsunami source with real bathymetry data. Comparison results demonstrate that the proposed method has considerably outperformed the conventional one in terms of model accuracy.

Bayesian tsunami-waveform inversion with trans-dimensional tsunami-source models

2014 ◽  
Vol 136 (4) ◽  
pp. 2085-2085
Author(s):  
Jan Dettmer ◽  
Jakir Hossen ◽  
Phil R. Cummins ◽  
Stan E. Dosso
Keyword(s):  
Waveform Inversion ◽  
Tsunami Source ◽  
Tsunami Waveform Inversion ◽  
Source Models ◽  
Tsunami Waveform

The Green's Function and its Oscillatory Properties for a Single Branch Structure of a Pinned Beam-Rod System

2011 ◽  
Vol 291-294 ◽  
pp. 2014-2020
Author(s):  
Min He ◽  
Qi Shen Wang
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Qualitative Properties ◽  
Direct Integral ◽  
Rod System ◽  
Support Conditions ◽  
Oscillation Properties ◽  
Single Branch ◽  
Oscillatory Properties

This paper concerns the determination of qualitative properties of linear vibrational systems, in particular for a single branch structure consisting of a pinned beam-rod system. First, we establish the characteristic equations satisfied by the Green’s function for this structure. The Green’s functions corresponding to support conditions where the left end of the beam was pinned-end are deduced by adopting the direct integral method. Using the theory of oscillation kernels established by Gantmakher and Krein, oscillatory properties of the Green's function for the beam-rod system are proved. Furthermore, four oscillation properties associated with frequencies and mode functions for the system are given.

scholarly journals Green’s Function for Dirac Particle in a Non-Abelian Field: A Path Integral Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-15
Author(s):  
Sami Boudieb ◽  
Lyazid Chetouani
Keyword(s):  
Green Function ◽  
Green’S Function ◽  
Green's Function ◽  
Path Integral ◽  
Dirac Particle ◽  
Integral Approach ◽  
Path Integral Approach ◽  
Abelian Field ◽  
The Green Function

The Green function for a Dirac particle moving in a non-Abelian field and having a particular form is exactly determined by the path integral approach. The wave functions were deduced from the residues of Green’s function. It is shown that the classical paths contributed mainly to the determination of the Green function.

Sign in / Sign up

Export Citation Format

Share Document