The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Hiroshi Katukura - One of the best experts on this subject based on the ideXlab platform.
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effective time domain soil structure interaction analysis based on fft algorithm with Causality Condition
Earthquake Engineering & Structural Dynamics, 1990Co-Authors: Yasuhiro Hayashi, Hiroshi KatukuraAbstract:We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with Causality Conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.
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Effective time‐domain soil‐structure interaction analysis based on FFT algorithm with Causality Condition
Earthquake Engineering & Structural Dynamics, 1990Co-Authors: Yasuhiro Hayashi, Hiroshi KatukuraAbstract:We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with Causality Conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.
Yasuhiro Hayashi - One of the best experts on this subject based on the ideXlab platform.
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effective time domain soil structure interaction analysis based on fft algorithm with Causality Condition
Earthquake Engineering & Structural Dynamics, 1990Co-Authors: Yasuhiro Hayashi, Hiroshi KatukuraAbstract:We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with Causality Conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.
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Effective time‐domain soil‐structure interaction analysis based on FFT algorithm with Causality Condition
Earthquake Engineering & Structural Dynamics, 1990Co-Authors: Yasuhiro Hayashi, Hiroshi KatukuraAbstract:We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with Causality Conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.
A N Valentyuk - One of the best experts on this subject based on the ideXlab platform.
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stochastic radiative transfer and Causality Condition
Journal of Quantitative Spectroscopy & Radiative Transfer, 1995Co-Authors: A N ValentyukAbstract:Abstract We consider the stochastic radiative transfer problem in random media with scattering by using a Causality Condition. Three classes of models are proposed to describe this problem. In low order models we assume that the solutions of the stochastic transfer equation satisfy the Causality Condition themselves. Only the solutions of the closure equations satisfy this Condition in higher order models. In the highest order models both the stochastic transfer equation and the closure equations (or only the closure equations) have the form of the series satisfying the Causality Condition. Our results describe nonstationary scattering and apply to any geometry of medium.
I. A. Khokhlov - One of the best experts on this subject based on the ideXlab platform.
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on the question of the Causality Condition in quantum field theory
Russian Physics Journal, 2017Co-Authors: I. A. KhokhlovAbstract:A mathematically correct generalization of the Bogoliubov microCausality Condition to the case of arbitrary points in spacetime is given. The proposed generalized formulation of the microCausality Condition is the basis for construction of a scattering matrix not containing ultraviolet divergences.
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The Causality Condition and the S-matrix in quantum field theory
Russian Physics Journal, 1993Co-Authors: I. A. KhokhlovAbstract:The most general mathematical formulation is given for the concept of Causality in quantum field theory. Based on it and on the Bogolyubov method, we construct the S-matrix of interacting quantized fields, being finite in each order of perturbation theory and satisfying all basic physical requirements.
George V. Vlasov - One of the best experts on this subject based on the ideXlab platform.
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Tachyonic thermal excitations and Causality
arXiv: High Energy Physics - Phenomenology, 2011Co-Authors: Ernst Trojan, George V. VlasovAbstract:We consider an ideal Fermi gas of tachyonic thermal excitations as a continuous medium and establish when it satisfies the Causality Condition. At high temperature the sound speed is always subluminal $c_s
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Acoustics of tachyon Fermi gas
Physical Review D, 2011Co-Authors: Ernst Trojan, George V. VlasovAbstract:We consider a Fermi gas of free tachyons as a continuous medium and find whether it satisfies the Causality Condition. There is no stable tachyon matter with the particle density below critical value n{sub T} and the Fermi momentum k{sub F} E is not forbidden. Existence of shock waves in tachyon gas is also discussed. At low density n{sub T}