ATOMOSYD
http://www.atomosyd.net/
Analyse TOpologique et MOdélisation de SYstèmes Dynamiques. ATOMOSYD is an acronym to designate the approach we develop to investigate dynamical systems. We are concerned by the topological analysis, that is, a global approach of the phase portrait, and by the possibility to obtain a set of differential equations from measurements. Our researches are performed in CORIA which belongs to CNRS.frSPIP  www.spip.netATOMOSYDhttp://atomosyd.net/index.php/includes/xml/dist/javascript/overlib/skelato/plugins/dw2/ecrire/IMG/siteon0.gif
http://www.atomosyd.net/
802132020
http://atomosyd.net/index.php/ecrire/spip.php?article206
http://atomosyd.net/index.php/ecrire/spip.php?article20620200210T15:31:41Ztext/htmlfrPapers
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Christophe Letellier, I. Leyva, and I. SendiñaNadal <br />Dynamical complexity measure to distinguish organized from disorganized dynamics <br />Physical Review E, 101, 022204, 2020. online <br />Abstract <br />We propose a metric to characterize the complex behavior of a dynamical system and to distinguish between organized and disorganized complexity. The approach combines two quantities that separately assess the degree of unpredictability of the dynamics and the lack of describability of the structure in the (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique13" rel="directory">Papers</a>
1984 Cord toroidal chaos
http://atomosyd.net/index.php/ecrire/spip.php?article205
http://atomosyd.net/index.php/ecrire/spip.php?article20520200122T19:30:34Ztext/htmlfrLetellier3D flows
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In order to investigate some bifurcations which can lead to turbulence, William F. Langford constructed a model designed for producing toroidal chaos . His objective was to investigate with a numerical approach the bifurcations that occur after the first appearance of an invariant torus. The particular interest of this model is that it is threedimensional. It reads as <br />For parameter values <br />this system produces a toroidal chaotic attractor shown in Fig. 1. <br />A poincaré section (Fig. 2) (...)

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Chaos in Nature (2019)
http://atomosyd.net/index.php/ecrire/spip.php?article204
http://atomosyd.net/index.php/ecrire/spip.php?article20420190510T13:19:18Ztext/htmlfrLetellierBooks
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A book on history of chaos

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique14" rel="directory">Books</a>
2019
http://atomosyd.net/index.php/ecrire/spip.php?article203
http://atomosyd.net/index.php/ecrire/spip.php?article20320190123T06:50:55Ztext/htmlfrLetellierPapers
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Fabrice Denis, Ethan Basch, AnneLise Septans, Jaafar Bennouna, Thierry Urban, Amylou C. Dueck & Christophe Letellier <br />Twoyear survival comparing webbased symptom monitoring vs routine surveillance following treatment for lung cancer, <br />JAMA. 321 (3), 306307, 2019. Online <br />Abstract <br />Symptom monitoring during chemotherapy via webbased patientreported outcomes (PROs) was previously demonstrated to lengthen survival in a singlecenter study.1 A multicenter randomized clinical trial compared (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique13" rel="directory">Papers</a>
1987 A normal form for the BelousovZhabotinski reaction
http://atomosyd.net/index.php/ecrire/spip.php?article202
http://atomosyd.net/index.php/ecrire/spip.php?article20220180902T12:27:37Ztext/htmlfrLetellier3D flows
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The simple threedimensional model <br />for describing the oscillations in the concentration of Ce ions was proposed by Françoise Argoul (University of Bordeaux) and coworkers. A numerical integration of this model (Fig. 1b) produces a chaotic attractor whose template contains the three branches which were identified in the experimental data. This model also captures the main characteristics of the experimental dynamics. When the parameter mu is varied, there is a perioddoubling cascade (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique5" rel="directory">3D flows</a>
1978 : The CurryYorke map
http://atomosyd.net/index.php/ecrire/spip.php?article201
http://atomosyd.net/index.php/ecrire/spip.php?article20120180827T12:15:45Ztext/htmlfrLetellierDiscrete maps
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James H. Curry and James Yorke proposed in 1978 a twodimensional map for a illustrating one of the routes to chaos from a quasiperiodic behavior. This map results from he composition of two simple homeomorphisms. The first homeomorphism is defined in polar coordinates by % <br />and the second is defined in Cartesian coordinates according to <br />The CurryYorke map is <br />The numerical invstigation starts with three typical behaviors solutions to the CurryYorke map, namely a quasiperiodic regime (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique7" rel="directory">Discrete maps</a>
A symbolic nonlinear theory for network observability
http://atomosyd.net/index.php/ecrire/spip.php?article200
http://atomosyd.net/index.php/ecrire/spip.php?article20020180525T11:36:54Ztext/htmlfrAGUIRRE, Letellier, SENDINANADALObservability of networks
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Work presented at NetSci 2018, Paris. <br />The observability of a complex system refers to the property of being able to infer its whole state by measuring the dynamics of a limited set of its variables. Since monitoring all the variables defining the system's state is experimentally infeasible or inefficient, it is of utmost importance to develop a methodological framework addressing the problem of targeting those variables yielding full observability. Despite several approaches have been (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique37" rel="directory">Observability of networks</a>
2018
http://atomosyd.net/index.php/ecrire/spip.php?article198
http://atomosyd.net/index.php/ecrire/spip.php?article19820180228T14:52:23Ztext/htmlfrPapers
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C. Letellier, I. SendiñaNadal, E. BiancoMartinez & M. S. Baptista <br />A symbolic networkbased nonlinear theory for dynamical systems observability <br />Scientific Reports, 8, 3785, 2018. <br />Abstract <br />When the state of the whole reaction network can be inferred by just measuring the dynamics of a limited set of nodes the system is said to be fully observable. However, as the number of all possible combinations of measured variables and time derivatives spanning the reconstructed state of the (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique13" rel="directory">Papers</a>
1987 The Ikeda delay differential equation
http://atomosyd.net/index.php/ecrire/spip.php?article197
http://atomosyd.net/index.php/ecrire/spip.php?article19720180106T17:22:52Ztext/htmlfrLetellierHigher dimensional flows
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Kensuke Ikeda proposed a model of a passive optical resonator system . When the system is an optical bistable resonator, Ikeda and Kenji Matsumoto showed that the dynamics can be reproduced with the single delay differential equation <br />For μ = 16 and x0 = π/3, δt = 0.002 and x(0)=2.5, the chaotic attractor shown in Fig. 1 is obtained. These parameter values were obtained by looking for a simple attractor starting from those provided by (...)

<a href="http://atomosyd.net/index.php/ecrire/spip.php?rubrique6" rel="directory">Higher dimensional flows</a>
1984 A piecewise system for quasiperiodic and chaotic motions
http://atomosyd.net/spip.php/skelato/)http:/www.davidsauzay.com/www.davidsauzay.com/spip.php?article196
http://atomosyd.net/spip.php/skelato/)http:/www.davidsauzay.com/www.davidsauzay.com/spip.php?article19620171118T15:53:34Ztext/htmlfrLetellier3D flows
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When b=0, this system is conservative and produces quasiperiodic motions as evidenced in the Poincaré section defined by y=0 and shown in Fig. 1. Using x0 = 0.1417, y0=z0=0, there is most likely a weakly chaotic toroidal motion (shown in green in Fig. 1.).

<a href="http://atomosyd.net/spip.php/skelato/)http:/www.davidsauzay.com/www.davidsauzay.com/spip.php?rubrique5" rel="directory">3D flows</a>