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Depósito Digital de Documentos de la UAB Encontrados 38 registros  1 - 10siguientefinal  ir al registro: La búsqueda tardó 0.06 segundos. 
1.
31 p, 607.7 KB On the cyclicity of Kolmogorov polycycles / Marín Pérez, David (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Villadelprat Yagüe, Jordi (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Centre de Recerca Matemàtica
In this paper we study planar polynomial Kolmogorov's differential systems Xμ{x˙=f(x,y;μ),y˙=g(x,y;μ), with the parameter μ varying in an open subset Λ⊂RN. Compactifying Xμ to the Poincaré disc, the boundary of the first quadrant is an invariant triangle Γ, that we assume to be a hyperbolic polycycle with exactly three saddle points at its vertices for all μ∈Λ. [...]
2022 - 10.14232/ejqtde.2022.1.35
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 35 (2022) , p. 1-31  
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2.
13 p, 535.8 KB Global phase portraits of a predator-prey system / Diz-Pita, Érika (Universidade de Santiago de Compostela. Departamento de Estatística, Análise Matemática e Optimización) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Otero-Espinar, M. Victoria (Universidade de Santiago de Compostela. Departamento de Estatística, Análise Matemática e Optimización)
We classify the global dynamics of a family of Kolmogorov systems depend-ing on three parameters which has ecological meaning as it modelizes a predator-prey system. We obtain all their topologically distinct global phase portraits in the positive quadrant of the Poincaré disc, so we provide all the possible distinct dynamics of these systems.
2022 - 10.14232/ejqtde.2022.1.16
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 2022, Issue 16 (2022) , p. 1-13
2 documentos
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3.
38 p, 850.7 KB Phase portraits of a family of Kolmogorov systems depending on six parameters / Diz-Pita, Érika (Universidade de Santiago de Compostela. Departamento de Estatística, Análise Matemática e Optimización) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Otero Espinar, Maria Victoria (Universidade de Santiago de Compostela. Departamento de Estatística, Análise Matemática e Optimización)
We consider a general 3-dimensional Lotka-Volterra system with a rational first integral of degree two of the form H = xi yj zk. The restriction of this Lotka-Volterra system to each surface H(x, y, z) = h varying h ∈ R provide Kolmogorov systems. [...]
2021
Electronic journal of differential equations, Vol. 2021, Issue 35 (2021) , p. 1-38
2 documentos
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4.
52 p, 1.1 MB Quadratic systems with an invariant algebraic curve of degree 3 and a Darboux invariant / Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Oliveira, Regilene (Universidade de São Paulo. Instituto de Ciências Matemáticas e Computação) ; Rodrigues, Camila A. B. (Universidade Federal de Santa Catarina. Departamento de Matemática (Brazil))
Let QS be the class of non-degenerate planar quadratic differential systems and QS3 its subclass formed by the systems possessing an invariant cubic f(x, y) = 0. In this article, using the action of the group of real affine transformations and time rescaling on QS, we obtain all the possible normalforms for the quadratic systems in QS3. [...]
2021
Electronic journal of differential equations, Vol. 2021, Issue 69 (2021) , p. 1-52
2 documentos
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5.
38 p, 2.1 MB Limit cycles of planar discontinuous piecewise linear hamiltonian systems without equilibria separated by reducible cubics / Benterki, Rebiha (Université Mohamed El Bachir El Ibrahimi. Département de Mathématiques (Algeria)) ; Jimenez Ruiz, Jeidy Johana (Universidade Federal do Oeste da Bahia (Brazil)) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques)
Due to their applications to many physical phenomena during these last decades the interest for studying the discontinuous piecewise differential systems has increased strongly. The limit cycles play a main role in the study of any planar differential system, but to determine the maximum number of limits cycles that a class of planar differential systems can have is one of the main problems in the qualitative theory of the planar differential systems. [...]
2021 - 10.14232/ejqtde.2021.1.69
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 2021, Issue 69 (2021) , p. 1-38
2 documentos
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6.
89 p, 1.8 MB Structurally unstable quadratic vector fields of codimension two : Families possessing a finite saddle-node and an infinite saddle-node / Artés Ferragud, Joan Carles (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Mota, Marcos Coutinho (Universidade de São Paulo. Instituto de Ciências Matemáticas e de Computação (Brazil)) ; Rezende, Alex C. (Universidade Federal de São Carlos. Departamento de Matemática (Brazil))
In 1998, Artés, Kooij and Llibre proved that there exist 44 structurally stable topologically distinct phase portraits modulo limit cycles, and in 2018 Artés, Llibre and Rezende showed the existence of at least 204 (at most 211) structurally unstable topologically distinct codimension-one phase portraits, modulo limit cycles. [...]
2021 - 10.14232/ejqtde.2021.1.35
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 2021, Issue 35 (2021) , p. 1-89
2 documentos
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7.
22 p, 816.7 KB Period function of planar turning points / Huzak, Renato (Hasselt University. Campus Diepenbeek (Belgium)) ; Rojas, David (Universitat de Girona. Departament d'Informàtica, Matemàtica Aplicada i Estadística)
This paper is devoted to the study of the period function of planar generic and non-generic turning points. In the generic case (resp. non-generic) a non-degenerate (resp. degenerate) center disappears in the limit ɛ → 0, where ɛ ≥ 0 is the singular perturbation parameter. [...]
2021 - 10.14232/ejqtde.2021.1.16
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 2021, Issue 16 (2021) , p. 1-21
2 documentos
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8.
34 p, 471.7 KB Stability index of linear random dynamical systems / Cimà, Anna (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Gasull, Armengol (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Mañosa Fernández, Víctor 1971- (Universitat Politècnica de Catalunya. Departament de Matemàtiques)
Given a homogeneous linear discrete or continuous dynamical system, its stability index is given by the dimension of the stable manifold of the zero solution. In particular, for the n dimensional case, the zero solution is globally asymptotically stable if and only if this stability index is n. [...]
2021 - 10.14232/ejqtde.2021.1.15
Electronic Journal of Qualitative Theory of Differential Equations, Vol. 2021, Issue 15 (2021) , p. 1-27
2 documentos
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9.
34 p, 1.2 MB Crossing limit cycles for a class of piecewise linear differential centers separated by a conic / Jimenez Ruiz, Jeidy Johana (Universidade Federal do Oeste da Bahia (Brasil)) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Medrado, Joao Carlos (Universidade Federal de Goiás. Instituto de Matemática e Estatística (Brasil))
These last years the study of the version of Hilbert's 16th problem for piecewise linear differential systems in the plane, has increased strongly and there are many papers studying the maximum number of crossing limit cycles when the differential system is defined in two zones separated by a straight line, in particular in [11, 13] it was proved that piecewise linear differential centers separated by a straight line have no crossing limit cycles, but in the papers [14, 15] it was shown that the maximum number of crossing limit cycles of piecewise linear differential centers, can change depending of the shape of the discontinuity curve. [...]
2020
Electronic journal of differential equations, Vol. 2020, Issue 41 (2020) , p. 1-36
2 documentos
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10.
16 p, 279.8 KB Linear type global centers of cubic Hamiltonian systems symmetric with respect to the x-axis / Barreira, Luis (Universidade de Lisboa. Instituto Superior Técnico. Departamento de Matemática (Portugal)) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Valls, Clàudia 1973- (Universidade de Lisboa. Instituto Superior Técnico. Departamento de Matemática (Portugal))
A polynomial differential system of degree 2 has no global centers (that is, centers defined in all the plane except the fixed point). In this paper we characterize the global centers of cubic Hamiltonian systems symmetric with respect to the x-axis, and such that the center has purely imaginary eigenvalues.
2020
Electronic journal of differential equations, Vol. 2020 Núm. 57 (2020) , p. 1-14
2 documentos
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Depósito Digital de Documentos de la UAB : Encontrados 38 registros   1 - 10siguientefinal  ir al registro:
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