{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T12:05:59Z","timestamp":1774526759918,"version":"3.50.1"},"reference-count":38,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,11,30]],"date-time":"2021-11-30T00:00:00Z","timestamp":1638230400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>We introduce an index based on information theory to quantify the stationarity of a stochastic process. The index compares on the one hand the information contained in the increment at the time scale \u03c4 of the process at time t with, on the other hand, the extra information in the variable at time t that is not present at time t\u2212\u03c4. By varying the scale \u03c4, the index can explore a full range of scales. We thus obtain a multi-scale quantity that is not restricted to the first two moments of the density distribution, nor to the covariance, but that probes the complete dependences in the process. This index indeed provides a measure of the regularity of the process at a given scale. Not only is this index able to indicate whether a realization of the process is stationary, but its evolution across scales also indicates how rough and non-stationary it is. We show how the index behaves for various synthetic processes proposed to model fluid turbulence, as well as on experimental fluid turbulence measurements.<\/jats:p>","DOI":"10.3390\/e23121609","type":"journal-article","created":{"date-parts":[[2021,11,30]],"date-time":"2021-11-30T20:29:27Z","timestamp":1638304167000},"page":"1609","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Quantifying Non-Stationarity with Information Theory"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4095-0807","authenticated-orcid":false,"given":"Carlos","family":"Granero-Belinch\u00f3n","sequence":"first","affiliation":[{"name":"Laboratoire de Physique, CNRS, Universit\u00e8 Claude Bernard Lyon 1, ENS de Lyon, Universit\u00e8 de Lyon, F-69342 Lyon, France"},{"name":"IMT Atlantique, Lab-STICC, UMR CNRS 6285, F-29238 Brest, France"}]},{"given":"St\u00e9phane G.","family":"Roux","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique, CNRS, Universit\u00e8 Claude Bernard Lyon 1, ENS de Lyon, Universit\u00e8 de Lyon, F-69342 Lyon, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1094-7201","authenticated-orcid":false,"given":"Nicolas B.","family":"Garnier","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique, CNRS, Universit\u00e8 Claude Bernard Lyon 1, ENS de Lyon, Universit\u00e8 de Lyon, F-69342 Lyon, France"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Beran, J., Feng, Y., Ghosh, S., and Kulik, R. 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