研究者詳細 - 竹中　博士

MISC - 竹中　博士

分割表示 351 件中 201 - 220 件目／全件表示 >>

A two-point, three-dimensional seismic ray tracing using genetic algorithms

H Sadeghi, S Suzuki, H Takenaka

PHYSICS OF THE EARTH AND PLANETARY INTERIORS 113 ( 1-4 ) 355 - 365 1999年6月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

Ray tracing between two fixed points is a boundary value problem. An initial path connecting two points, the source and the receiver, is algorithmically perturbed until it converges to a solution giving a minimum travel-time path. In multi-pathing cases, it is quite possible for an algorithm to converge to a ray path with local minimum travel time. Furthermore, when the velocity structure has discontinuities, there is another serious problem, i.e., how to determine the correct intersection between the ray and the surface of discontinuity. In this paper, a new approach for two-point ray tracing is presented, which uses genetic algorithms (GAs) to overcome these problems. Since GAs are efficient global search techniques, the proposed method guarantees to find a global minimum travel-time path and also the correct intersections. A micro-GA implementation is adopted to further enhance computational efficiency. This approach is suitable for tracing the first arriving seismic waves through a 3-D heterogeneous medium with discontinuities. The method can also find the minimum time paths of later arrivals, such as reflected and refracted waves, by constraining the ray to hit a prescribed interface. The accuracy of the method is demonstrated on the numerical examples. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0031-9201(99)00011-4

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A two-point, three-dimensional seismic ray tracing using genetic algorithms (共著)

SADEGHI H, SUZUKI S, TAKENAKA H

Phys. Earth Planet. Int. 113 ( 1-4 ) 355 - 365 1999年6月

Pseudosepctral法による理論地震記象(6) -大規模3次元並列計算のための微分演算子の最適化-

古村孝志, 纐纈一起, 竹中博士

物理探査学会学術講演会講演論文集 = Proceeding of the SEGJ Conference 100 103 - 107 1999年6月

K-NET観測点の地震計方位測定(1):鹿児島県西部(共著)

竹中博士, 渡邉篤志, 藤原広行, 藤井雄士郎, 永野一

九大理学部研究報告(地球惑星) 20 ( 3 ) 89 - 98 1999年

記述言語：日本語出版者・発行元：九州大学理学部

Orientation of seismometers at 12 observatories of the K-NET in western Kagoshima region (KGSOO1～KGS012) was measured in this study. We found that stations KGS006 and KGS009 have rather large misorientation greater than 15°．We quickly check the effects of such instrument misorientation on waveform using the records of the 1997 northwestern Kagoshima earthquakes.

DOI： 10.15017/4494281

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鹿児島県串木野市の岩盤上における広帯域強震観測(共著)

九大理学部研究報告(地球惑星) 20 ( 3 ) 79 - 88 1999年

地震トモグラフィによる九州背弧のマントル・アップウエリング構造と九州の張力場(共著)

月刊地球 ( 号外27 ) 211 - 216 1999年

速度-応力型スタガード格子差分法を用いた2次元及び3次元地震波動計算コードの作成(共著)

九州大学理学部研究報告(地球惑星科学) 20 ( 3 ) 99 - 110 1999年

K-NET観測点の地震計方位測定(1)鹿児島県西部

竹中博士, 渡邉篤志, 藤原広行

九州大学理学部研究報告地球惑星科学 20 ( 3 ) 89 - 98 1999年

Broadband strong-motion of observation on hard rock site at Kushikino

Atsushi Watanabe, Yushiro Fujii, Hayato Futamure, Nobuki Kame, Hiroshi Takenaka, Sadaomi Skuzuki, Kenji Uehira, Takeshi Matsushima

Sci. Repts., Dept. Earth & Planet. Sci., Kyushu Univ. 20 ( 3 ) 79 - 88 1999年

In 1997, two moderate earthquakes occurred in the northwestern part of Kagoshima Prefecture (Mjma 6.5 on March 26 and Mjma 6.3 on May 13), and a large number of aftershocks occurred in the southern part of the second event focal region. We started the observation of the aftershocks from April 1, 1998, at Kushikino. We used a broadband strong-motion velocity-type seismograph and an accelerograph in order to record the full waveforms of the strong ground motions. Up to April 25, 1999, we observed 74 events, and 3 events were recorded by both seismographs. In this paper, we report the detail of observational conditions and show some waveforms we obtained.

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Simulating seismic wave propagation in transversely isotropic media by using pseudo-spectral method(共著)

Northwestern Seismological Journal 21 ( 2 ) 212 - 224 1999年

Development of 2D and 3D codes of the velocity-stress staggered-grid finite-difference method for modeling seismic wave propagation

HAYASHIDA T.

Sci. Repts., Dept. Earth and Planet. Sci., Kyushu Univ. 20 ( 3 ) 99 - 110 1999年

Simulating seismic wave propagation in transversely isotropic media by using pseudo-spectral method(共著)

Northwestern Seismological Journal 21 ( 2 ) 212 - 224 1999年

An efficient approach of the pseudospectral method for modeling of geometrically symmetric seismic wavefield(共著)

Earth, Planets and Space 51 ( 2 ) 73 - 79 1999年

An efficient approach of the pseudospectral method for modelling of geometrically symmetric seismic wavefield

H Takenaka, YB Wang, T Furumura

EARTH PLANETS AND SPACE 51 ( 2 ) 73 - 79 1999年

記述言語：英語出版者・発行元：TERRA SCIENTIFIC PUBL CO

The pseudospectral method is a high-accuracy numerical modelling technique that requires less computer memory and computation time than the traditional techniques such as the finite-difference method. These advantages of the pseudospectral method have enabled us to practically apply this method to modelling realistic problems that have complex structure and source models. However, a major drawback of such numerical schemes for discrete grid models is that even for rather a simple structural model they require as much computational requirements (e.g. computation time and memory) as for an entirely complex structural model with the same size of the simple one. We actually need to employ idealised simple models, such as a model with geometrical symmetry, to investigate basic phenomena of seismic waves, to develop new techniques, or to choose optimal values of some computational parameters for more complex modelling. In this paper we propose an efficient approach of an economical pseudospectral method for calculation of wavefields in models symmetric with respect to a vertical plane or two orthogonal vertical planes. Using this approach, the wavefields only need to be computed in a half or quarter domain of the models, so that the computer memory and computation time can be reduced ideally by half or quarter, respectively, as compared with the calculation of the entire models.

DOI： 10.5636/eps.51.73

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マルチバンドパスフィルターを用いたS波最大振幅解析による地震波放射特性の周波数依存に関する考察

侭田豊, 二牟礼勇人, 竹中博士

日本地震学会秋季大会講演予稿集 1999 1999年