Effectiveness of the Bendixson–Dulac theorem
| Autor: | Hector Giacomini, Armengol Gasull |
|---|---|
| Přispěvatelé: | Departament de Matemàtiques [Barcelona] (UAB), Universitat Autònoma de Barcelona (UAB), Institut Denis Poisson (IDP), Centre National de la Recherche Scientifique (CNRS)-Université de Tours-Université d'Orléans (UO), This work has received funding from the Ministerio de Ciencia e Innovación (PID2019-104658GB-I00 grant) and the Agència de Gestió d’Ajuts Universitaris i de Recerca (2017 SGR 1617grant)., Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Université d'Orléans (UO) |
| Rok vydání: | 2021 |
| Předmět: |
Pure mathematics
Applied Mathematics [MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS] Limit cycle Function (mathematics) Type (model theory) MSC 2010 : Primary: 34C07. Secondary: 37C27 Curvature Periodic orbit Mathematics - Classical Analysis and ODEs Bendixson–Dulac theorem Classical Analysis and ODEs (math.CA) FOS: Mathematics Liénard equation Vector field Limit (mathematics) [MATH]Mathematics [math] Bendixson-Dulac theorem Analysis Sign (mathematics) Mathematics |
| Zdroj: | Dipòsit Digital de Documents de la UAB Universitat Autònoma de Barcelona |
| ISSN: | 0022-0396 |
| DOI: | 10.1016/j.jde.2021.10.011 |
| Popis: | 22 pages, 30 réf.; We illustrate with several new applications the power and elegance of the Bendixson–Dulac theorem to obtain upper bounds of the number of limit cycles for several families of planar vector fields. In some cases we propose to use a function related with the curvature of the orbits of the vector field as a Dulac function. We get some general results for Li´enard type equations and for rigid planar systems. We also present a remarkable phenomenon: for each integer m ≥ 2, we provide a simple 1-parametric differential system for which we prove that it has limit cycles only for the values of the parameter in a subset of an interval of length smaller that 3√2(3/m)m/2 that decreases exponentially when m grows. One of the strengths of the results presented in this work is that although they are obtained with simple calculations, that can be easily checked by hand, they improve and extend previous studies. Another one is that, for certain systems, it is possible to reduce the question of the number of limit cycles to the study of the shape of a planar curve and the sign of an associated function in one or two variables. |
| Databáze: | OpenAIRE |
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