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. 2005 Mar;71(3 Pt 1):032102.
doi: 10.1103/PhysRevE.71.032102. Epub 2005 Mar 22.

Some properties of the entropy in the natural time

P A Varotsos  1 , N V Sarlis, H K Tanaka, E S Skordas
Affiliations

Some properties of the entropy in the natural time

P A Varotsos et al. Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Mar.

Abstract

We show that the entropy S , defined as S identical with chi ln chi - chi ln chi [Phys. Rev. E 68, 031106 (2003)] where chi stands for the natural time [Phys. Rev. E 66, 011902 (2002)], exhibits positivity and concavity as well as stability or experimental robustness. Furthermore, the distinction between the seismic electric signal activities and "artificial" noises, based on the classification of their S values, is lost when studying the time-reversed signals. This reveals the profound importance of considering the (true) time arrow.

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