### Abstract

Non-Gaussian characteristics in time series of the Alfven chaos system are discussed. The phase coherence index, a measure defined by using the surrogate data method and the structure function, is used to evaluate the phase coherence among the Fourier modes. Through Monte Carlo significance testing, it is found that the phase coherence decays monotonically with increasing dissipative parameter and time scale. By applying the Mori projection operator method assuming the Markov process, a model equation for the time correlation function is derived from the generalized Langevin equation. As opposed to the result of the phase coherence analysis, it is concluded that the difference between the direct numerical simulation and the model equation becomes pronounced as the dissipative parameters are increased. This suggests that, even when the phase coherence index is not significant, the underlying physical system may be a non-Gaussian process.

Original language | English |
---|---|

Article number | 033J01 |

Journal | Progress of Theoretical and Experimental Physics |

Volume | 2017 |

Issue number | 3 |

DOIs | |

Publication status | Published - Mar 1 2017 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)

### Cite this

*Progress of Theoretical and Experimental Physics*,

*2017*(3), [033J01]. https://doi.org/10.1093/ptep/ptx016

**Phase coherence among the Fourier modes and non-Gaussian characteristics in the Alfvén chaos system.** / Nariyuki, Yasuhiro; Sasaki, Makoto; Kasuya, Naohiro; Hada, Tohru; Yagi, Masatoshi.

Research output: Contribution to journal › Article

*Progress of Theoretical and Experimental Physics*, vol. 2017, no. 3, 033J01. https://doi.org/10.1093/ptep/ptx016

}

TY - JOUR

T1 - Phase coherence among the Fourier modes and non-Gaussian characteristics in the Alfvén chaos system

AU - Nariyuki, Yasuhiro

AU - Sasaki, Makoto

AU - Kasuya, Naohiro

AU - Hada, Tohru

AU - Yagi, Masatoshi

PY - 2017/3/1

Y1 - 2017/3/1

N2 - Non-Gaussian characteristics in time series of the Alfven chaos system are discussed. The phase coherence index, a measure defined by using the surrogate data method and the structure function, is used to evaluate the phase coherence among the Fourier modes. Through Monte Carlo significance testing, it is found that the phase coherence decays monotonically with increasing dissipative parameter and time scale. By applying the Mori projection operator method assuming the Markov process, a model equation for the time correlation function is derived from the generalized Langevin equation. As opposed to the result of the phase coherence analysis, it is concluded that the difference between the direct numerical simulation and the model equation becomes pronounced as the dissipative parameters are increased. This suggests that, even when the phase coherence index is not significant, the underlying physical system may be a non-Gaussian process.

AB - Non-Gaussian characteristics in time series of the Alfven chaos system are discussed. The phase coherence index, a measure defined by using the surrogate data method and the structure function, is used to evaluate the phase coherence among the Fourier modes. Through Monte Carlo significance testing, it is found that the phase coherence decays monotonically with increasing dissipative parameter and time scale. By applying the Mori projection operator method assuming the Markov process, a model equation for the time correlation function is derived from the generalized Langevin equation. As opposed to the result of the phase coherence analysis, it is concluded that the difference between the direct numerical simulation and the model equation becomes pronounced as the dissipative parameters are increased. This suggests that, even when the phase coherence index is not significant, the underlying physical system may be a non-Gaussian process.

UR - http://www.scopus.com/inward/record.url?scp=85017096953&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85017096953&partnerID=8YFLogxK

U2 - 10.1093/ptep/ptx016

DO - 10.1093/ptep/ptx016

M3 - Article

AN - SCOPUS:85017096953

VL - 2017

JO - Progress of Theoretical and Experimental Physics

JF - Progress of Theoretical and Experimental Physics

SN - 2050-3911

IS - 3

M1 - 033J01

ER -