The Experts below are selected from a list of 118029 Experts worldwide ranked by ideXlab platform
Koichiro Tanaka - One of the best experts on this subject based on the ideXlab platform.
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the intermolecular stretching Vibration Mode in water isotopes investigated with broadband terahertz time domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Hiroyuki Yada, Masaya Nagai, Koichiro TanakaAbstract:Abstract We determined the complex dielectric constants of the liquid water isotopes, H 2 O, D 2 O, and H 2 18 O at 296 K from 0.2 to 7 THz by terahertz time-domain attenuated total reflection spectroscopy. We extracted the dispersion of the complex susceptibility of the intermolecular stretching Vibration Mode around 5 THz. The isotope effect on the Vibration Mode is clarified in its amplitude, frequency, and damping constant. Anticorrelation of the oscillator strength of the intermolecular stretching Vibration Mode between infrared activity and Raman activity indicates that H 2 O has the strongest structural disorder among water isotopes.
David Chelidze - One of the best experts on this subject based on the ideXlab platform.
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blind source separation based Vibration Mode identification
Mechanical Systems and Signal Processing, 2007Co-Authors: Wenliang Zhou, David ChelidzeAbstract:In this paper, a novel method for linear normal Mode (LNM) identification based on blind source separation (BSS) is introduced. Modal coordinates are considered as a specific case of sources that have certain time structure. This structure makes modal coordinates identifiable by many BSS algorithms. However, algorithms based on second-order statistics are particularly suited for extracting LNMs of a Vibration system. Two well-known BSS algorithms are considered. First, algorithm for multiple unknown signals extraction (AMUSE) is used to illustrate the similarity with Ibrahim time domain (ITD) modal identification method. Second, second order blind identification (SOBI) is used to demonstrate noise robustness of BSS-based Mode shape extraction. Numerical simulations and experimental results from these BSS algorithms and ITD method are presented.
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smooth orthogonal decomposition based Vibration Mode identification
Journal of Sound and Vibration, 2006Co-Authors: David Chelidze, Wenliang ZhouAbstract:A new multivariate data analysis method called smooth orthogonal decomposition (SOD) is proposed to extract linear normal Modes and natural frequencies of multi-degree-of-freedom and distributed-parameter Vibration systems. It is demonstrated that for an undamped free Vibration of a multi-degree-of-freedom system, the computed smooth orthogonal Modes are in direct correspondence with the actual normal Vibration Modes and the smooth orthogonal values are related to the corresponding natural frequencies. The same is also shown to be true for lightly damped free Vibrations of both lumped- and distributed-parameter systems. In contrast to the intrinsic limitations of the proper orthogonal decomposition (POD) analysis, which requires the knowledge of system's mass matrix to extract normal Modes and cannot uniquely identify modal subspaces that have similar proper orthogonal values, the SOD is shown to overcome both of these deficiencies. Numerical examples are provided to compare the performances of the POD- and SOD-based modal identification in various types of Vibration environment.
Hiroyuki Yada - One of the best experts on this subject based on the ideXlab platform.
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the intermolecular stretching Vibration Mode in water isotopes investigated with broadband terahertz time domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Hiroyuki Yada, Masaya Nagai, Koichiro TanakaAbstract:Abstract We determined the complex dielectric constants of the liquid water isotopes, H 2 O, D 2 O, and H 2 18 O at 296 K from 0.2 to 7 THz by terahertz time-domain attenuated total reflection spectroscopy. We extracted the dispersion of the complex susceptibility of the intermolecular stretching Vibration Mode around 5 THz. The isotope effect on the Vibration Mode is clarified in its amplitude, frequency, and damping constant. Anticorrelation of the oscillator strength of the intermolecular stretching Vibration Mode between infrared activity and Raman activity indicates that H 2 O has the strongest structural disorder among water isotopes.
Wenliang Zhou - One of the best experts on this subject based on the ideXlab platform.
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blind source separation based Vibration Mode identification
Mechanical Systems and Signal Processing, 2007Co-Authors: Wenliang Zhou, David ChelidzeAbstract:In this paper, a novel method for linear normal Mode (LNM) identification based on blind source separation (BSS) is introduced. Modal coordinates are considered as a specific case of sources that have certain time structure. This structure makes modal coordinates identifiable by many BSS algorithms. However, algorithms based on second-order statistics are particularly suited for extracting LNMs of a Vibration system. Two well-known BSS algorithms are considered. First, algorithm for multiple unknown signals extraction (AMUSE) is used to illustrate the similarity with Ibrahim time domain (ITD) modal identification method. Second, second order blind identification (SOBI) is used to demonstrate noise robustness of BSS-based Mode shape extraction. Numerical simulations and experimental results from these BSS algorithms and ITD method are presented.
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smooth orthogonal decomposition based Vibration Mode identification
Journal of Sound and Vibration, 2006Co-Authors: David Chelidze, Wenliang ZhouAbstract:A new multivariate data analysis method called smooth orthogonal decomposition (SOD) is proposed to extract linear normal Modes and natural frequencies of multi-degree-of-freedom and distributed-parameter Vibration systems. It is demonstrated that for an undamped free Vibration of a multi-degree-of-freedom system, the computed smooth orthogonal Modes are in direct correspondence with the actual normal Vibration Modes and the smooth orthogonal values are related to the corresponding natural frequencies. The same is also shown to be true for lightly damped free Vibrations of both lumped- and distributed-parameter systems. In contrast to the intrinsic limitations of the proper orthogonal decomposition (POD) analysis, which requires the knowledge of system's mass matrix to extract normal Modes and cannot uniquely identify modal subspaces that have similar proper orthogonal values, the SOD is shown to overcome both of these deficiencies. Numerical examples are provided to compare the performances of the POD- and SOD-based modal identification in various types of Vibration environment.
Masaya Nagai - One of the best experts on this subject based on the ideXlab platform.
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the intermolecular stretching Vibration Mode in water isotopes investigated with broadband terahertz time domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Hiroyuki Yada, Masaya Nagai, Koichiro TanakaAbstract:Abstract We determined the complex dielectric constants of the liquid water isotopes, H 2 O, D 2 O, and H 2 18 O at 296 K from 0.2 to 7 THz by terahertz time-domain attenuated total reflection spectroscopy. We extracted the dispersion of the complex susceptibility of the intermolecular stretching Vibration Mode around 5 THz. The isotope effect on the Vibration Mode is clarified in its amplitude, frequency, and damping constant. Anticorrelation of the oscillator strength of the intermolecular stretching Vibration Mode between infrared activity and Raman activity indicates that H 2 O has the strongest structural disorder among water isotopes.