The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Jeroen Ritsema - One of the best experts on this subject based on the ideXlab platform.
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The TauP Toolkit: Flexible Seismic Travel-time and Ray-Path Utilities
Seismological Research Letters, 2011Co-Authors: H. P. Crotwell, T. J. Owens, Jeroen RitsemaAbstract:INTRODUCTION The calculation of travel times and Ray Paths of seismic phases for a specified velocity model of the Earth has always been a fundamental need of seismologists. In recent years, the number of different phases used in analysis has been growing, as has the availability of new Earth models, especially models developed from detailed regional studies. These factors highlight the need for versatile utilities that allow the calculation of travel times and Ray Paths of (ideally) any conceivable seismic phase passing through (ideally) arbitrary velocity models. The method of Buland and Chapman (1983) provides significant progress toward this need by allowing for the computation of times and Paths of any Rays passing through arbitrary spherically symmetric velocity models. The implementation of this method through the ttimes software program (Kennett and Engdahl, 1991) for a limited number of velocity models and a standard set of seismic phases has been widely...
Hiroyuki Nagahama - One of the best experts on this subject based on the ideXlab platform.
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finsler geometry of seismic Ray Path in anisotropic media
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2009Co-Authors: Takahiro Yajima, Hiroyuki NagahamaAbstract:The seismic Ray theory in anisotropic inhomogeneous media is studied based on non-Euclidean geometry called Finsler geometry. For a two-dimensional Ray Path, the seismic wavefront in anisotropic media can be geometrically expressed by Finslerian parameters. By using elasticity constants of a real rock, the Finslerian parameters are estimated from a wavefront propagating in the rock. As a result, the anisotropic parameters indicate that the shape of wavefront is expressed not by a circle but by a convex curve called a superellipse. This deviation from the circle as an isotropic wavefront can be characterized by a roughness of wavefront. The roughness parameter of the real rock shows that the shape of the wavefront is expressed by a fractal curve. From an orthogonality of the wavefront and the Ray, the seismic wavefront in anisotropic media relates to a fractal structure of the Ray Path.
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kawaguchi space zermelo s condition and seismic Ray Path
Nonlinear Analysis-real World Applications, 2007Co-Authors: Takahiro Yajima, Hiroyuki NagahamaAbstract:Abstract Based on Kawaguchi space, a seismic Ray Path through an anisotropic medium corresponds to an arclength under Zermelo's condition. From a special function in Kawaguchi space, we obtain some Finslerian metrics ( m th root metric or 1-form metric). Considering a variational problem of the seismic Ray, Snell's law is derived from Euler's vector, and envelopes of seismic wavefront are classified by m -values in seismic Finsler metric. Moreover, we discuss the relation between Kawaguchi space and another Ray theory.
Jun-ichi Takada - One of the best experts on this subject based on the ideXlab platform.
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ISPACS - Three-Ray Path loss based on peak power loss for ultra wideband impulse radio systems
2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011Co-Authors: Pichaya Supanakoon, Saksit Chaiyapong, Sathaporn Promwong, Jun-ichi TakadaAbstract:Path loss is important parameter to analyze and design link budget. For indoor environment, there is fading that occurs in Path loss. Therefore, accurate Path loss model, which is considered fading, is necessary. In this paper, three-Ray Path loss based on peak power loss is proposed for ultra wideband impulse radio (UWB-IR) systems. The rectangular passband is used as UWB-IR transmitted signal. The extension of Friis' transmission formula is applied for UWB-IR three-Ray channel. The received signal is evaluated. The closed form formula of three-Ray Path loss is derived based on peak power loss. The Path loss from proposed model was illustrated and compared with three-Ray model based on average power loss and free space model. This model can be used to study the characteristic of fading and extended to multi-Ray Path loss model for indoor environment.
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Three-Ray Path loss based on peak power loss for ultra wideband impulse radio systems
2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011Co-Authors: Pichaya Supanakoon, Saksit Chaiyapong, Sathaporn Promwong, Jun-ichi TakadaAbstract:Path loss is important parameter to analyze and design link budget. For indoor environment, there is fading that occurs in Path loss. Therefore, accurate Path loss model, which is considered fading, is necessary. In this paper, three-Ray Path loss based on peak power loss is proposed for ultra wideband impulse radio (UWB-IR) systems. The rectangular passband is used as UWB-IR transmitted signal. The extension of Friis' transmission formula is applied for UWB-IR three-Ray channel. The received signal is evaluated. The closed form formula of three-Ray Path loss is derived based on peak power loss. The Path loss from proposed model was illustrated and compared with three-Ray model based on average power loss and free space model. This model can be used to study the characteristic of fading and extended to multi-Ray Path loss model for indoor environment.
H. P. Crotwell - One of the best experts on this subject based on the ideXlab platform.
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The TauP Toolkit: Flexible Seismic Travel-time and Ray-Path Utilities
Seismological Research Letters, 2011Co-Authors: H. P. Crotwell, T. J. Owens, Jeroen RitsemaAbstract:INTRODUCTION The calculation of travel times and Ray Paths of seismic phases for a specified velocity model of the Earth has always been a fundamental need of seismologists. In recent years, the number of different phases used in analysis has been growing, as has the availability of new Earth models, especially models developed from detailed regional studies. These factors highlight the need for versatile utilities that allow the calculation of travel times and Ray Paths of (ideally) any conceivable seismic phase passing through (ideally) arbitrary velocity models. The method of Buland and Chapman (1983) provides significant progress toward this need by allowing for the computation of times and Paths of any Rays passing through arbitrary spherically symmetric velocity models. The implementation of this method through the ttimes software program (Kennett and Engdahl, 1991) for a limited number of velocity models and a standard set of seismic phases has been widely...
Takahiro Yajima - One of the best experts on this subject based on the ideXlab platform.
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finsler geometry of seismic Ray Path in anisotropic media
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2009Co-Authors: Takahiro Yajima, Hiroyuki NagahamaAbstract:The seismic Ray theory in anisotropic inhomogeneous media is studied based on non-Euclidean geometry called Finsler geometry. For a two-dimensional Ray Path, the seismic wavefront in anisotropic media can be geometrically expressed by Finslerian parameters. By using elasticity constants of a real rock, the Finslerian parameters are estimated from a wavefront propagating in the rock. As a result, the anisotropic parameters indicate that the shape of wavefront is expressed not by a circle but by a convex curve called a superellipse. This deviation from the circle as an isotropic wavefront can be characterized by a roughness of wavefront. The roughness parameter of the real rock shows that the shape of the wavefront is expressed by a fractal curve. From an orthogonality of the wavefront and the Ray, the seismic wavefront in anisotropic media relates to a fractal structure of the Ray Path.
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kawaguchi space zermelo s condition and seismic Ray Path
Nonlinear Analysis-real World Applications, 2007Co-Authors: Takahiro Yajima, Hiroyuki NagahamaAbstract:Abstract Based on Kawaguchi space, a seismic Ray Path through an anisotropic medium corresponds to an arclength under Zermelo's condition. From a special function in Kawaguchi space, we obtain some Finslerian metrics ( m th root metric or 1-form metric). Considering a variational problem of the seismic Ray, Snell's law is derived from Euler's vector, and envelopes of seismic wavefront are classified by m -values in seismic Finsler metric. Moreover, we discuss the relation between Kawaguchi space and another Ray theory.
