Projecte

General

Perfil

Tasca #4360 » llistaarticles20161201.txt

Tomas Fabregat, 11-01-2017 16:10

 
<entry>
type: Phdthesis
aigaionid: 3474
bibtexid: Per2012
title: On the number of limit cycles for some families of planar differential equations
author: Pérez-González, Set
year: 2012
school: Universitat Autònoma de Barcelona
address: Bellaterra (Barcelona)
file: Per2012.pdf-5e3f269f95266208c9e1351a7404c1df.pdf
</entry>
<entry>
type: Article
aigaionid: 3412
bibtexid: BuzLli2012a
title: On the periodic solutions of the static, spherically symmetric {E}instein-{Y}ang-{M}ills equations
author: Buzzi, Claudio Aguinaldo
author: Llibre, Jaume
journal: Journal of Mathematical Physics
year: 2012
volume: 53
startpage: 122703
file: BuzLli2012a.pdf-58b7545892b6a81c1f37aaa8183d0d80.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 3607
bibtexid: Bol2013
title: Generalizations of the {D}arboux integrability theory for polynomial vector fields
author: Bolaños Rivera, Yudi Marcela
year: 2013
school: Universitat Autònoma de Barcelona
address: Bellaterra
note: In Spanish
file: Bol2013.pdf-83db7f3ff7ccb7d46bccdb469778b625.pdf
</entry>
<entry>
type: Article
aigaionid: 3668
bibtexid: ArtLliSchVul2013b
title: Geometric configurations of singularities for quadratic differential systems with three distinct real simple finite singularities
author: Artés, Joan Carles
author: Llibre, Jaume
author: Schlomiuk, Dana
author: Vulpe, Nicolae
journal: Journal of Fixed Point Theory and Applications
year: 2013
volume: 14
number: 2
startpage: 555
endpage: 618
doi: 10.1007/s11784-014-0175-2
keywords: geometric equivalence relation
keywords: Quadratic vector fields
keywords: Singularities
abstract: In this work we classify, with respect to the geometric equivalence relation, the global configurations of singularities, finite and infinite, of quadratic differential systems possessing exactly three distinct finite simple singularities. This relation is finer than the topological equivalence relation which does not distinguish between a focus and a node or between a strong and a weak focus or between foci (or saddles) of different orders. Such distinctions are, however, important in the production of limit cycles close to the foci (or loops) in perturbations of the systems. The notion of geometric equivalence relation of configurations of singularities allows us to incorporate all these important geometric features which can be expressed in purely algebraic terms. The geomet
ric classification of all configurations of singularities, finite and infinite, of quadratic systems was initiated in a work published in 2013 when the classification was done for systems with total multiplicity m f of finite singularities less than or equal to one. That work was continued in an article which is due to appear in 2014 where the geometric classification of configurations of singularities was done for the case m f = 2. In this article we go one step further and obtain the geometric classification of singularities, finite and infinite, for the subclass mentioned above. We
obtain 147 geometrically distinct configurations of singularities for this family. We give here the global bifurcation diagram of configurations of singularities, both finite and infinite, with respect to the geometric equivalence relation, for this class of systems. The bifurcation set of this diagram is algebraic. The bifurcation diagram is done in the 12-dimensional space of parameters and it is expressed in terms of polynomial invariants, a fact which gives us an algorithm for determining the geometric configuration of singularities for any quadratic system in this
particular class.
file: ArtLliSchVul2013.pdf-d07a39d224471f46d61731058071cac7.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4411
bibtexid: Gey2013
title: On some aspects of nonlinear water wave theory
author: Geyer, Anna
year: 2013
school: University of Vienna
address: Vienna
file: Gey2013.pdf-9799ad0bbfc602dfef4cc084dbec7862.pdf
</entry>
<entry>
type: Article
aigaionid: 2337
bibtexid: CaoLliZha2014
title: Darboux integrability and Algebraic limit cycles for a class of polynomial differential Systems
author: Cao, Jinlong
author: Llibre, Jaume
author: Zhang, Xiang
journal: Science China Mathematics
year: 2014
volume: 57
number: 4
startpage: 775
endpage: 794
doi: 10.1007/s11425-014-4772-8
keywords: Algebraic limit cycles
keywords: Darboux first integral
file: CaoLliZha2008.pdf-5d4cbd46028da8ae.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4109
bibtexid: Col2014
title: Hamiltonian linear type centers and nilpotent centers of linear plus cubic polynomial vector fields
author: Colak, Ilker
year: 2014
school: Universitat Autònoma de Barcelona
address: Bellaterra (Barcelona)
keywords: Center
keywords: cubic Hamiltonian
file: Col2014.pdf-6fca9c12c74bd08fa038bcc4a008a3d2.pdf
</entry>
<entry>
type: Mastersthesis
aigaionid: 4347
bibtexid: Gou2014
title: Classification of centers and study of limit cycles for piecewise linear systems in two zones on the plane
author: Gouveia, Luiz Fernando da Silva
year: 2014
school: Universidade Estadual Paulista "Júlio de Mesquita Filho"
address: Sao Jose do Rio Preto
note: In Portuguese
file: Gou2014.pdf-20a8304a0962eb45c2bb6ccaebb5dbc8.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4412
bibtexid: Zaf2014
title: Dynamical Classification of some Birational Maps of ${C}^2$
author: Zafar, Sundus
year: 2014
school: Univertiat Autònoma de Barcelona
address: Bellaterra
file: Zaf2014.pdf-cb733cb1342a34e5b4a385a33d986684.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4413
bibtexid: Gar2014b
title: A qualitative and quantitative study of some planar differential equations
author: García Saldaña, Johanna Denise
year: 2014
school: Universitat Autònoma de Barcelona
address: Bellaterra
file: Gar2014.pdf-0f845db272411cc3404ddf602746dba7.pdf
</entry>
<entry>
type: Article
aigaionid: 4142
bibtexid: LliLon2015
title: Periodic solutions for the generalized anisotropic {L}ennard-{J}ones {H}amiltonian
author: Llibre, Jaume
author: Long, Yiming
journal: Qualitative Theory of Dynamical Systems
year: 2015
volume: 14
startpage: 291
endpage: 311
doi: 10.1007/s12346-015-0167-7
keywords: anisotropic Lennard-Jones potential
keywords: circular periodic solutions
keywords: Lennard-Jones potential
file: LliLon2015.preprint.pdf-80a5fbedf6b8204c9b8f7e2b3630c916.pdf
</entry>
<entry>
type: Incollection
aigaionid: 4333
bibtexid: BarCopr2015
title: Convex Central Configurations of Two Twisted n-gons
author: Barrabes, Esther
author: Cors, Josep Maria
booktitle: Extended Abstracts Spring 2014 (Hamiltonian Systems and Celestial Mechanics, Virus Dynamics and Evolution)
series: Trends in Mathematics. Research Perspectives CRM Barcelona
year: 2015
volume: 4
startpage: 17
endpage: 21
publisher: Birkhäuser
doi: 10.1007/978-3-319-22129-8_3
file: BarCor2015.Preprint.pdf-3e0b94a1be3fd5530a1593525b6f6e3d.pdf
</entry>
<entry>
type: Article
aigaionid: 3438
bibtexid: Lli2015c
title: On the 16-{H}ilbert Problem
author: Llibre, Jaume
journal: La Gaceta de la Real Sociedad Matemática Española
year: 2015
volume: 18
number: 3
startpage: 543
endpage: 554
note: In Spanish
abstract: Presentamos un breve resumen de algunos resultados recientes sobre la segunda parte del problema 16 de Hilbert, poniendo un especial énfasis en los ciclos límite algebraicos.
file: Lli2012.pdf-2879fca33a006d0e9d7ae091e9574c03.pdf
</entry>
<entry>
type: Article
aigaionid: 3539
bibtexid: LliVid2015
title: Periodic solutions of a periodic {F}itz{H}ugh-{N}agumo differential system
author: Llibre, Jaume
author: Vidal, Claudio
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2015
volume: 25
number: 13
startpage: 1550180 (6 pages)
doi: 10.1142/S0218127415501801
keywords: Averaging theory
keywords: FitzHugh-Nagumo system
keywords: periodic orbit
abstract: Recently some interest has appeared for the periodic FitzHugh–Nagumo differential systems. Here, we provide sufficient conditions for the existence of periodic solutions in such differential systems.
file: LliVid2013.pdf-042bf8e1e52b3438535fd924b5f3300a.pdf
</entry>
<entry>
type: Article
aigaionid: 3550
bibtexid: BolLliVal2015
title: Liouvillian first integrals for quadratic systems with an integrable saddle
author: Bolaños Rivera, Yudi Marcela
author: Llibre, Jaume
author: Valls, Clàudia
journal: The Rocky Mountain Journal of Mathematics
year: 2015
volume: 45
number: 6
startpage: 1765
endpage: 1779
doi: 10.1216/RMJ-2015-45-6-1765
keywords: integrable saddle
keywords: Integrating factor
keywords: Inverse integrating factor
keywords: Liouvillian first integral
keywords: quadratic systems
abstract: We provide explicit expressions for the Liouvillian first integrals of the quadratic polynomial differential systems having an integrable saddle.
file: BolLliVal2013b.pdf-ed17a96e763f27b868a1f65dbaaa9d1a.pdf
</entry>
<entry>
type: Article
aigaionid: 3687
bibtexid: LliVal2015l
title: Analytic integrability of a class of planar polynomial differential systems
author: Llibre, Jaume
author: Valls, Clàudia
journal: Discrete and Continuous Dynamical Systems. Series B
year: 2015
volume: 20
number: 8
startpage: 2657
endpage: 2661
doi: 10.3934/dcdsb.2015.20.2657
file: LliVal2014b.pdf-8c5f12362cd82cace24995a949f057e4.pdf
</entry>
<entry>
type: Article
aigaionid: 3718
bibtexid: GuiLliVer2016
title: Periodic orbits of a perturbed 3–dimensional isotropic oscillator with axial symmetry
author: Guirao, Juan Luis Garcia
author: Llibre, Jaume
author: Vera, Juan A.
journal: Nonlinear Dynamics. An International Journal of Nonlinear Dynamics and Chaos in Engineering Systems
year: 2015
volume: 83
startpage: 839
endpage: 848
doi: 10.1007/s11071-015-2371-z
abstract: We study the periodic orbits of a generalized Yang–Mills Hamiltonian H depending on a parameter β. Playing with the parameter β we are considering extensions of the Contopoulos and of the Yang–Mills Hamiltonians in a 3-dimensional space. This Hamiltonian consists of a 3-dimensional isotropic harmonic oscillator plus a homogeneous potential of fourth degree having an axial symmetry, which implies that the third component N of the angular momentum is constant. We prove that in each invariant space H = h > 0 the Hamiltonian system has at least four periodic solutions if either β < 0, or β = 5 sqrt(13); and at least 12 periodic solutions if β > 6 and β != 5 sqrt(13). We also study the linear stability or instability of these periodic solutions.
file: GuiLliVer2014.preprint.pdf-3483bc0923d8387d6cee827c29d6c294.pdf
</entry>
<entry>
type: Article
aigaionid: 3749
bibtexid: LliNovTei2015d
title: On the periodic solutions of perturbed 4D non-resonant systems
author: Llibre, Jaume
author: Novaes, Douglas D.
author: Teixeira, Marco Antonio
journal: Sao Paulo Journal of Mathematics
year: 2015
volume: 9
startpage: 229
endpage: 250
doi: 10.1007/s40863-015-0017-1
keywords: Averaging theory
keywords: Double pendulum
keywords: Non-resonant systems
keywords: Non-smooth dynamical systems
keywords: periodic solution
abstract: We provide sufficient conditions for the existence of periodic solutions of a 4D non-resonant system perturbed by smooth or non-smooth functions. We apply these results to study the small amplitude periodic solutions of the non-linear planar double pendulum perturbed by smooth or non-smooth function.
file: LliNovTei2014a.Preprint.pdf-6cedd7faadbbbd97275239a551194b73.pdf
</entry>
<entry>
type: Article
aigaionid: 3771
bibtexid: BerFagRem2015
title: Hyperbolic entire functions with bounded {F}atou components
author: Bergweiler, Walter
author: Fagella, Nuria
author: Rempe, Lasse
journal: Commentarii Mathematici Helvetici. A Journal of the Swiss Mathematical Society
year: 2015
volume: 90
number: 4
startpage: 799
endpage: 829
doi: 10.4171/CMH/371
keywords: Axiom A
keywords: Bounded Fatou component
keywords: Eremenko-Lyubich class
keywords: Fatou set
keywords: Hyperbolicity
keywords: Jordan curve
keywords: Julia set
keywords: Laguerre-Pólya class
keywords: Local connectivity
keywords: Quasicircle
keywords: Quasidisc
keywords: Transcendental entire function
abstract: We show that an invariant Fatou component of a hyperbolic transcendental entire function is a Jordan domain (in fact, a quasidisc) if and only if it contains only finitely many critical points and no asymptotic curves. We use this theorem to prove criteria for the boundedness of Fatou components and local connectivity of Julia sets for hyperbolic entire functions, and give examples that demonstrate that our results are optimal. A particularly strong dichotomy is obtained in the case of a function with precisely two critical values.
file: BerFagRem2014.preprint.pdf-b06df4e5df71eb1b445c49522463f97a.pdf
</entry>
<entry>
type: Article
aigaionid: 3774
bibtexid: GarGod2015
title: On {M}c{M}ullen-like mappings
author: Garijo, Antoni
author: Godillon, Sebastién
journal: Journal of Fractal Geometry
year: 2015
volume: 2
startpage: 249
endpage: 279
doi: 10.4171/JFG/21
keywords: complex dynamics
keywords: Julia sets
keywords: McMullen family
keywords: rational maps
abstract: We introduce a generalization of the McMullen family $f_\lambda(z) = z^n \lambda/zd^$. In 1988 C. McMullen showed that the Julia set of $f_\lambda$ is a Cantor set of circles if and only if $1/n 1/d < 1$ and the simple critical values of $f_\lambda$ belong to the trap door. We generalize this behavior and we define a McMullen-like mapping as a rational map f associated to a hyperbolic postcritically finite polynomial $P$ and a pole data $\mathcal D$ where we encode, basically, the location of every pole of f and the local degree at each pole. In the McMullen family the polynomial $P$ is $z\mapsto z^n$ and the pole data $\mathcal D$ is the pole located at the origin that maps to infinity with local degree $d$. As in the McMullen family $f_\lambda$, we can characterize a McMullen-like mapping using an arithmetic condition depending only on the polynomial $P$ and the pole data $\mathcal D$. We prove that the arithmetic condition is necessary using the theory of Thurston's obstructions, and sufficient by quasiconformal surgery.
file: GarGod2014.preprint.pdf-9318b10fc87acdb693853a6ba840077a.pdf
</entry>
<entry>
type: Article
aigaionid: 4112
bibtexid: Gas2015h
title: Fórmules i filatèlia
author: Gasull, Armengol
journal: Notícies de la Societat Catalana de Matemàtiques
year: 2015
volume: 37
startpage: 49
endpage: 54
file: Gas2014.preprint.pdf-8fdb34f4c9b4d26b3d8983e44a4d6507.pdf
</entry>
<entry>
type: Article
aigaionid: 4126
bibtexid: ArtRezOli2015
title: The geometry of quadratic polynomial differential systems with a finite and an infinite saddle-node (C)
author: Artés, Joan Carles
author: Rezende, Alex Carlucci
author: Oliveira, Regilene D. S.
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2015
volume: 25
number: 3
doi: 10.1142/S0218127415300098
keywords: algebraic invariants
keywords: bifurcation diagram
keywords: finite saddle-node
keywords: infinite saddle-node
keywords: Phase portrait
keywords: Quadratic differential systems
file: ArtRezOli2014a.preprint.pdf-7cda85e6ca7167c8f30eace42afaec80.pdf
</entry>
<entry>
type: Article
aigaionid: 4134
bibtexid: LliYu2015
title: Global phase portraits of quadratic systems with an ellipse and a straight line as invariant algebraic curves
author: Llibre, Jaume
author: Yu, Jiang
journal: Electronic Journal of Differential Equations
year: 2015
volume: 314
startpage: 1
endpage: 14
keywords: First integral
keywords: global phase portraits
keywords: invariant ellipse
keywords: invariant straight line
keywords: quadratic system
abstract: In this article we study a class of integrable quadratic systems and classify all its phase portraits. More precisely, we characterize the class of all quadratic polynomial differential systems in the plane having an ellipse and a straight line as invariant algebraic curves. We show that this class is integrable and we provide all the different topological phase portraits that this class exhibits in the Poincaré disc.
file: LliYu2014.preprint.pdf-3d8b4a35293f5fa2e6461b4f0dc6c9a7.pdf
</entry>
<entry>
type: Article
aigaionid: 4144
bibtexid: Gas2015
title: Bótes i barrils
author: Gasull, Armengol
journal: Nou Biaix
year: 2015
volume: 36
startpage: 8
endpage: 28
abstract: In this paper we consider the validity of several practical formulas used to calculate the volume of wine or cider barrels. In our study we will find, for instance, Simpson’s formula for calculating definite integrals; a book written by Kepler on the subject; and the method of least squares established by Gauss and Legendre, for calculating the best solution for overdetermined and incompatible systems.
file: Gas2015.Preprint.pdf-4e84eb2ee5779ab4b29251abb6ad6bb2.pdf
</entry>
<entry>
type: Article
aigaionid: 4233
bibtexid: GinLli2015
title: Canards existence in {F}itz{H}ugh-{N}agumo and {H}odgkin-{H}uxley neuronal models
author: Ginoux, Jean-Marc
author: Llibre, Jaume
journal: Mathematical Problems in Engineering
year: 2015
volume: 2015
number: 342010
startpage: 17pp.
doi: 10.1155/2015/342010
keywords: canard solutions
keywords: Geometric singular perturbation theory
keywords: singularly perturbed dynamical systems
abstract: In a previous paper we have proposed a new method for proving the existence of "canard solutions" for three and four-dimensional singularly perturbed systems with only one fast variable. The aim of this work is to extend this method to the case of four-dimensional singularly perturbed systems with two slow and two fast variables. This method enables to state a unique generic condition for the existence of "canard solutions" for such four-dimensional singularly perturbed systems which is based on the stability of folded singularities (pseudo singular points in this case) of the normalized slow dynamics deduced from a well-known property of linear algebra. This unique generic condition is perfectly identical to that provided in previous works. Applications of this method to the famous coupled FitzHugh-Nagumo equations and to the Hodgkin-Huxley model enables to show the existence of "canard solutions" in such systems.
file: GinLli2015.Preprint.pdf-4f4cccd998fdb402e9d2645d72b5f32b.pdf
</entry>
<entry>
type: Article
aigaionid: 4338
bibtexid: LemLli2015
title: Periodic orbits for a generalized {F}riedmann-{R}obertson-{W}alker {H}amiltonian system in dimension 6
author: Lembarki, Fatima E.
author: Llibre, Jaume
journal: Discrete and Continuous Dynamical Systems. Series S
year: 2015
volume: 8
number: 6
startpage: 1165
endpage: 1211
doi: 10.3934/dcdss.2015.8.1165
keywords: Averaging theory
keywords: fam- ily of periodic orbits
keywords: Friedmann-Robertson-Walker
keywords: periodic orbits
keywords: periodic orbits parameterized by the energy
abstract: A generalized Friedmann-Robertson-Walker Hamiltonian system is studied in dimension 6. The averaging theory is the tool used to provide sufficient conditions on the six parameters of the system which guarantee the existence of continuous families of period orbits parameterized by the energy.
file: LemLli2015.Preprint.pdf-25aa0e4d12d874ec6da57a66e73869bc.pdf
</entry>
<entry>
type: Inbook
aigaionid: 4346
bibtexid: Lli2015d
title: The Averaging Theory for Computing Periodic Orbits
author: Llibre, Jaume
booktitle: Central Configurations, Periodic Orbits, and Hamiltonian Systems
series: Advanced Courses in Mathematics - CRM Barcelona
year: 2015
publisher: Birkhäuser Basel
address: CRM Barcelona
isbn: 978-3-0348-0932-0
doi: 10.1007/978-3-0348-0933-7
file: Lli2015d.Preprint.pdf-0f9b7fcb859c6aecd036b8e08ebeb950.pdf
</entry>
<entry>
type: Article
aigaionid: 4348
bibtexid: LliNovTei2015c
title: Periodic solutions of Lienard differential equations via averaging theory of order two
author: Llibre, Jaume
author: Novaes, Douglas D.
author: Teixeira, Marco Antonio
journal: Anais da Academia Brasileira de Ciencias
year: 2015
volume: 87
number: 4
startpage: 1905
endpage: 1913
doi: 10.1590/0001-3765201520140129
keywords: Averaging theory
keywords: bifurcation theory
keywords: Lienard differential equation
keywords: periodic solution
file: LliNovTei2015c.Preprint.pdf-4ce18f3d5a5db8fb5edde490013ed896.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4414
bibtexid: Can2015
title: On a Family of Degree 4 Blaschke Products
author: Canela, Jordi
year: 2015
school: Universitat de Barcelona
address: Barcelona
file: Can2015.pdf-bb908c52f17193168948c327c1d51bee.pdf
</entry>
<entry>
type: Article
aigaionid: 3441
bibtexid: PerTorTor2016
title: Existence and uniqueness of limit cycles for generalized $\varphi$-{L}aplacian {L}iénard equations
author: Pérez-González, Set
author: Torregrosa, Joan
author: Torres, Pedro J.
journal: Journal of Mathematical Analysis and Applications
year: 2016
volume: 439
startpage: 745
endpage: 765
doi: http://dx.doi.org/10.1016/j.jmaa.2016.03.004
keywords: Existence and Uniqueness
keywords: Generalized Liénard equations.
keywords: limit cycles
keywords: periodic orbits
keywords: φ-Laplacian Liénard equations
file: PerTorTor2016.Preprint.pdf-8c1777e2277ba5d95b67704a4207356d.pdf
</entry>
<entry>
type: Article
aigaionid: 3541
bibtexid: LliMak2016a
title: Zero-{H}opf periodic orbit of a non-autonomous quadratic differential system obtained from third-equations
author: Llibre, Jaume
author: Makhlouf, Ammar
journal: Chaos, Solitons and Fractals
year: 2016
volume: 89
startpage: 228
endpage: 231
doi: 10.1016/j.chaos.2015.11.013
keywords: Averaging theory
keywords: Michelson system
keywords: periodic solution
keywords: Triple-zero bifurcation
keywords: zero-Hopf bifurcation
abstract: We provide sufficient conditions for the existence of two periodic solutions bifurcating from a zero–Hopf equilibrium for the differential system
x ̇ =y, y ̇ =z, z ̇ =a by cz−x^2/2,
where a, b and c are real arbitrary parameters. The regular perturbation of this differential system provides the normal form of the so–called triple–zero bifurcation.
file: LliMak2013a.pdf-376659084510b753d1260f55afeb41d4.pdf
</entry>
<entry>
type: Article
aigaionid: 3554
bibtexid: LliVal2016d
title: On the polynomial integrability of a system motivated by the {R}iemann ellipsoid problem
author: Llibre, Jaume
author: Valls, Clàudia
journal: ESAIM. Control, Optimisation and Calculus of Variations
year: 2016
volume: 22
startpage: 872
endpage: 882
doi: 10.1051/cocv/2015035
keywords: complete integrability
keywords: Euler–Poinsot systems
keywords: homogeneous differential systems
keywords: polynomial first integral
keywords: Riemann ellipsoid problem
abstract: We consider differential systems obtained by coupling two Euler–Poinsot systems. The motivation to consider such systems can be traced back to the Riemann ellipsoid problem. We provide new cases for which these systems are completely integrable. We also prove that these systems either are completely integrable or have at most four functionally independent analytic first integrals.
file: LliVal2013h.pdf-ff4df2ae4997678daeea1d024b8e2aaf.pdf
</entry>
<entry>
type: Article
aigaionid: 3723
bibtexid: Reb2016
title: Poincaré–{P}ontryagin–{M}elnikov functions for a class of perturbed planar {H}amiltonian equations
author: Rebollo-Perdomo, Salomón
journal: Qualitative Theory of Dynamical Systems
year: 2016
doi: 10.1007/s12346-015-0185-5
abstract: In this paper we consider polynomial perturbations of a family of polynomial Hamiltonian equations whose associated Hamiltonian is not transversal to infinity, and its complexification is not a Morse polynomial. We look for an algorithm to compute the first non-vanishing Poincaré–Pontryagin–Melnikov function of the displacement function associated with the perturbed equation. We show that the algorithm of the case when the Hamiltonian is transversal to infinity and its complexification is a Morse polynomial can be extended to our family of perturbed equations. We apply the result to study the maximum number of zeros of the first non-vanishing Poincaré–Pontryagin–Melnikov function associated with some perturbed Hamiltonian equations.
file: Reb-Per2014.pdf-434c014d9bb2d4bc153f6a431871c8c6.pdf
</entry>
<entry>
type: Article
aigaionid: 3763
bibtexid: LliValZha2016
title: Liouvillian integrability versus {D}arboux polynomials
author: Llibre, Jaume
author: Valls, Clàudia
author: Zhang, Xiang
journal: Qualitative Theory of Dynamical Systems
year: 2016
volume: 15
startpage: 503
endpage: 515
doi: 10.1007/s12346-016-0212-1
keywords: Darboux Jacobian multiplier
keywords: Darboux polynomial
keywords: Liouvillian integrability
keywords: Polynomial differential systems
abstract: In this note we provide a sufficient condition on the existence of Darboux polynomials of polynomial differential systems via existence of Jacobian multiplier or of Liouvillian first integral and a degree condition among different components of the system. As an application of our main results we prove that the Liénard polynomial differential system $x ̇ = y, y ̇ = − f (x)y − g(x)$ with $deg f > deg g$ is not Liouvillian integrable.
file: LliValZha2014b.preprint.pdf-48ffa3ab292f530e15c5ede2c6cb9223.pdf
</entry>
<entry>
type: Article
aigaionid: 3776
bibtexid: LliTeiZel2016
title: Birth of limit cycles for a classe of continuous and discontinuous differential systems in (d 2)-dimension
author: Llibre, Jaume
author: Teixeira, Marco Antonio
author: Zeli, Iris O.
journal: Dynamical Systems. An International Journal
year: 2016
volume: 31
number: 3
startpage: 237
endpage: 250
doi: 10.1080/14689367.2015.1102868
keywords: Averaging theory
keywords: discontinuous polynomial differential system
keywords: limit cycle
keywords: periodic orbit
file: LliTeiZel2014.preprint.pdf-779911ace565ca58e8d5e8eca0e4f86c.pdf
</entry>
<entry>
type: Article
aigaionid: 4015
bibtexid: LliRamRamSad2016
title: The 16th {H}ilbert problem restricted to circular algebraic limit cycles
author: Llibre, Jaume
author: Ramírez, Rafael Orlando
author: Ramírez, Valentín
author: Sadovskaia, Natalia
journal: Journal of Differential Equations
year: 2016
volume: 260
startpage: 5726
endpage: 5760
doi: 10.1016/j.jde.2015.12.019 0022-0396
keywords: Darboux integrability
keywords: invariant algebraic circles
keywords: Planar polynomial differential system
keywords: Polynomial vector fields
abstract: We prove the following two results. First every planar polynomial vector field of degree S with S invariant circles is Darboux integrable without limit cycles. Second a planar polynomial vector field of degree S admits at most S - 1 invariant circles which are algebraic limit cycles. In particular we solve the 16th Hilbert problem restricted to algebraic limit cycles given by circles, because a planar polynomial vector field of degree S has at most S - 1 algebraic limit cycles given by circles, and this number is reached.
file: LliRamRamSad2014.preprint.pdf-eda8a23e48b5a8d554587ac4fce2cfef.pdf
</entry>
<entry>
type: Article
aigaionid: 4070
bibtexid: FerVal2016
title: On the {D}arboux integrability of a cubic {C}{R}{N}{T} model in $\mathbb {R}^5$
author: Ferragut, Antoni
author: Valls, Clàudia
journal: Chaos, Solitons and Fractals
year: 2016
volume: 82
startpage: 131
endpage: 138
doi: 10.1016/j.chaos.2015.11.011
keywords: chemical reaction network
keywords: Darboux integrability
keywords: Darboux polynomial
keywords: Exponential factor
file: FerVal2014b.preprint.pdf-d4e85b08ae6af0125a221da8aa0d06a5.pdf
</entry>
<entry>
type: Article
aigaionid: 4102
bibtexid: LliLopMor2016
title: Limit cycles bifurcating from the periodic annulus of the weight-homogeneous polynomial centers of weight-degree 2
author: Llibre, Jaume
author: Lopes, Bruno D.
author: de Moraes, Jaime R.
journal: Applied Mathematics and Computation
year: 2016
volume: 274
startpage: 47
endpage: 54
doi: 10.1016/j.amc.2015.10.079
keywords: Averaging theory
keywords: limit cycle
keywords: Polinomial vector field
keywords: weight-homogeneous differential system
abstract: We obtain an explicit polynomial whose simple positive real roots provide the limit cycles which bifurcate from the periodic orbits of a family of cubic polynomial differential centers when it is perturbed inside the class of all cubic polynomial differential systems. The family considered is the unique family of weight-homogeneous polynomial differential systems of weight-degree 2 with a center. The computations has been done with the help of the algebraic manipulator Mathematica.
file: LliLopMor2014b.preprint.pdf-f630c67919e8d673d0589e74c2adf458.pdf
</entry>
<entry>
type: Article
aigaionid: 4104
bibtexid: GarGiaGinLli2016
title: Analytic nilpotent centers as limits of nondegenerate centers revisited
author: García, Isaac A.
author: Giacomini, Hector
author: Giné, Jaume
author: Llibre, Jaume
journal: Journal of Mathematical Analysis and Applications
year: 2016
volume: 441
startpage: 893
endpage: 899
doi: 10.1016/j.jmaa.2016.04.046
keywords: Nilpotent center
keywords: Poincaré-Lyapunov constants
abstract: We prove that all the nilpotent centers of planar analytic differential systems are limit of centers with purely imaginary eigenvalues, and consequently the Poincaré-Liapunov method to detect centers with purely imaginary eigenvalues can be used to detect nilpotent centers.
file: GarGiaGinLli2014.preprint.pdf-79870d0efd2b5a7803b070434f962af0.pdf
</entry>
<entry>
type: Article
aigaionid: 4106
bibtexid: CorLliVal2016
title: Periodic motion in perturbed elliptic oscillators revisited
author: Corbera, Montserrat
author: Llibre, Jaume
author: Valls, Clàudia
journal: Astrophysics and Space Science. An International Journal of Astronomy, Astrophysics and Space Science
year: 2016
volume: 361:348
startpage: 1
endpage: 8
doi: 10.1007/s10509-016-2927-5
keywords: Averaging theory
keywords: galactic potential
abstract: We analytically study the Hamiltonian system in $\mathbb{R}^4$ with Hamiltonian $$ H= \frac12 (p_x^2 p_y^2) \frac{1}{2} (\omega_1^2 x^2 \omega_2^2 y^2)- \varepsilon\, V_1(x,y) $$ being (a) $V_1(x,y)=-(xy^2 ax^3)$ and (b) $V_1(x,y)=-(x^2y ax^3)$ with $a\in\mathbb{R}$, where $\varepsilon$ is a small parameter and $\omega_1$ and $\omega_2$ are the unperturbed frequencies of the oscillations along the $x$ and $y$ axis, respectively. For the potential (a) using averaging theory of first order we analytically find for each $a\in\mathbb{R}$ eight families of periodic solutions in every positive energy level of $H$ when the frequencies are not equal. For the potential (b) using averaging theory of first and second order we analytically find seven families of periodic solutions in every positive energy level of $H$ when the frequencies are not equal. Four of these seven families are defined for all $a\in\mathbb{R}$ whereas the other three are defined for all $a\ne 0$. Moreover, we provide the shape of all these families of periodic solutions. These Hamiltonians may represent the central parts of deformed galaxies and thus have been extensively used and studied numerically in order to describe local motion in galaxies near an equilibrium point.
file: CorLliVal2015.Preprint.pdf-6158277bc0a63c12cf5c433737ab3ba9.pdf
</entry>
<entry>
type: Article
aigaionid: 4117
bibtexid: GasGinTor2016
title: Center problem for systems with two monomial nonlinearities
author: Gasull, Armengol
author: Giné, Jaume
author: Torregrosa, Joan
journal: Communications on Pure and Applied Analysis
year: 2016
volume: 15
number: 2
startpage: 577
endpage: 598
doi: 10.3934/cpaa.2016.15.577
keywords: Darboux center
keywords: Holomorphic center
keywords: nondegenerate center
keywords: Persistent center.
keywords: Poincaré–Lyapunov constants
keywords: Reversible center
abstract: We study the center problem for planar systems with a linear center at the origin that in complex coordinates have a nonlinearity formed by the sum of two monomials. Our first result lists several centers inside this family. To the best of our knowledge this list includes a new class of Darboux centers that are also persistent centers. The rest of the paper is dedicated to try to prove that the given list is exhaustive. We get several partial results that
seem to indicate that this is the case. In particular, we solve the question for several general families with arbitrary high degree and for all cases of degree less or equal than 19. As a byproduct of our study we also obtain the highest known order for weak-foci of planar polynomial systems of some given degrees.
file: GasGinTor2014.Preprint.pdf-0ca92203e1ffa3504cdeba898d77c0e4.pdf
</entry>
<entry>
type: Article
aigaionid: 4131
bibtexid: Lli2016
title: A counterexample to a result on {L}otka-{V}olterra systems
author: Llibre, Jaume
journal: Acta Applicandae Mathematicae. An International Survey Journal on Applying Mathematics and Mathematical Applications
year: 2016
volume: 142
startpage: 123
endpage: 125
doi: 10.1007/s10440-015-0019-0
keywords: Hopf bifurcation
keywords: Lotka-Volterra system
abstract: In the article of Dancsó et al. (Acta Appl. Math. 23:103–127, 1991) the authors claim the existence of a Hopf bifurcation which in general does not exist.
file: Lli2014c.preprint.pdf-bb747ffd388034151b6645c8a511136d.pdf
</entry>
<entry>
type: Article
aigaionid: 4145
bibtexid: GeyMan2016
title: Singular solutions for a class of traveling wave equations arising in hydrodynamics
author: Geyer, Anna
author: Mañosa, Víctor
journal: Nonlinear Analysis: Real World Applications
year: 2016
volume: 31
startpage: 57
endpage: 76
doi: 10.1016/j.nonrwa.2016.01.009 1468-1218/ © 2016
keywords: Camassa-Holm equation
keywords: integrable vector fields
keywords: singular ordinary differential equations
keywords: traveling waves
abstract: We give an exhaustive characterization of singular weak solutions for ordinary differential equations of the form $\ddot{u}\,u \frac{1}{2}\dot{u}^2 F'(u) =0$, where $F$ is an analytic function. Our motivation stems from the fact that in the context of hydrodynamics several prominent equations are reducible to an equation of this form
upon passing to a moving frame. We construct peaked and cusped waves, fronts with finite-time decay and compact solitary waves. We prove that one cannot obtain peaked and compactly supported traveling waves for the
same equation. In particular, a peaked traveling wave cannot have compact support and vice versa. To exemplify the approach we apply our results to the Camassa-Holm equation and the equation for surface waves of moderate amplitude, and show how the different types of singular solutions can be obtained varying the energy level of the corresponding planar Hamiltonian systems.
file: GeyMan2015.Preprint.pdf-613a41def63c5af366c54788c7566fef.pdf
</entry>
<entry>
type: Article
aigaionid: 4150
bibtexid: LiaTor2016a
title: Centers of projective vector fields of spatial quasi-homogeneous systems with weight (m,m,n) and degree 2 on the sphere
author: Liang, Haihua
author: Torregrosa, Joan
journal: Electronic Journal of Qualitative Theory of Differential Equations
year: 2016
volume: 103
startpage: 1
endpage: 26
doi: 10.14232/ejqtde.2016.1.103
keywords: projective vector field
keywords: quasi-homogeneous system
keywords: sufficient and necessary conditions for centers
abstract: In this paper we study the centers of projective vector fields $\mathbf{Q}_T$ of three-dimensional quasi-homogeneous differential system $d\mathbf{x}/dt=\mathbf{Q}(\mathbf{x})$ with the weight $(m,m,n)$ and degree $2$ on the unit sphere $\mathbb{S}^2$. We seek the sufficient and necessary conditions under which $\mathbf{Q}_T$ has at least one center on $\mathbb{S}^2$. Moreover, we provide the exact number and the positions of the centers of $\mathbf{Q}_T$. First we give the complete classification of systems $d\mathbf{x}/dt=\mathbf{Q}(\mathbf{x})$ and then, using the induced systems of $\mathbf{Q}_T$ on the local charts of $\mathbb{S}^2,$ we determine the conditions for the existence of centers.

The results of this paper provide a convenient criterion to find out all the centers of $\mathbf{Q}_T$ on $\mathbb{S}^2$ with $\mathbf{Q}$ being the quasi-homogeneous polynomial vector field of weight $(m,m,n)$ and degree $2$.
file: LiangTorregrosa2015a.pdf-6cecfc42679260cae24d063fbcc38b26.pdf
</entry>
<entry>
type: Article
aigaionid: 4151
bibtexid: LiaLliTor2016
title: Limit cycles coming from some uniform isochronous centers
author: Liang, Haihua
author: Llibre, Jaume
author: Torregrosa, Joan
journal: Advanced Nonlinear Studies
year: 2016
volume: 16
number: 2
startpage: 197
endpage: 220
doi: 10.1515/ans-2015-5010
keywords: Averaging theory
keywords: uniform isochronous centers
keywords: weak Hilbert problem
abstract: This article is about the weak 16--th Hilbert problem, i.e. we analyze how many limit cycles can bifurcate from the periodic orbits of a given polynomial differential center when it is perturbed
inside a class of polynomial differential systems. More precisely, we consider the uniform isochronous centers
\[
\dot x= -y x^2 y (x^2 y^2)^n, \dot y= x x y^2 (x^2 y^2)^n,
\]
of degree $2n 3$ and we perturb them inside the class of all polynomial differential systems of degree $2n 3$. For $n=0,1$ we provide the maximum number of limit cycles, 3 and 8 respectively, that can bifurcate from the periodic orbits of these centers using averaging theory of first order, or equivalently Abelian integrals. For $n=2$ we show that at least 12 limit cycles can bifurcate from the periodic orbits of the center.
file: LiaLliTor2016.Preprint.pdf-715fd2f6ef7d837c41852685691b3a46.pdf
</entry>
<entry>
type: Article
aigaionid: 4153
bibtexid: LliSil2016
title: Global phase portraits of {K}ukles differential systems with homogenous polynomial nonlinearities of degree 5 having a center and their small limit cycles
author: Llibre, Jaume
author: Silva, Mauricio Fronza da
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2016
volume: 26
number: 3
startpage: 1650044 (25 pages)
doi: 10.1142/S0218127416500449
keywords: Centers
keywords: Kukles
keywords: Phase portrait
keywords: Poincaré disk
keywords: Polynomial vector fields
abstract: We provide the nine topological global phase portraits in the {P}oincaré disk of the family of the centers of Kukles polynomial differential systems of the form $\cdot x = -y$, $\cdot y= x ax^5y bx^3y^3 cxy^5$, where $x,y\in\R$ and $a,b,c$ are real parameters satisfying $a^2 b^2 c^2\neq 0$. Using averaging theory up to sixth order we determine the number of limit cycles which bifurcate from the origin when we perturb this system first inside the class of all homogeneous polynomial differential systems of degree 6, and second inside the class of all polynomial differential systems of degree 6.
file: LliSil2015.Preprint.pdf-b44b3c54348fb081e3d875c1d14f3f82.pdf
</entry>
<entry>
type: Article
aigaionid: 4166
bibtexid: ItiLli2016
title: Global phase portraits of uniform isochronous centers with quartic homogeneous polynomial nonlinearities
author: Itikawa, Jackson
author: Llibre, Jaume
journal: Discrete and Continuous Dynamical Systems. Series B
year: 2016
volume: 21
number: 1
startpage: 121
endpage: 131
doi: 10.3934/dcdsb.2016.21.121
keywords: Phase portrait
keywords: Poincaré disk
keywords: Polynomial vector field
keywords: uniform isochronous center
abstract: We classify the global phase portraits in the Poincar\'{e} disc of the differential systems $\dot{x}=-y xf(x,y),$ $\dot{y}=x yf(x,y)$, where $f(x,y)$ is a homogeneous polynomial of degree 3. These systems have a uniform isochronous center at the origin. This paper together with the results presented in \cite{IL2} completes the classification of the global phase portraits in the Poincar\'{e} disc of all quartic polynomial differential systems with a uniform isochronous center at the origin.
file: ItiLli2015.Preprint.pdf-c5163ae09fe6565de66363668539b522.pdf
</entry>
<entry>
type: Article
aigaionid: 4187
bibtexid: ManrojVil2016
title: The criticality of centers of potential systems at the outer boundary
author: Mañosas, Francesc
author: Rojas, David
author: Villadelprat, Jordi
journal: Journal of Differential Equations
year: 2016
volume: 260
startpage: 4918
endpage: 4972
doi: 10.1016/j.jde.2015.11.040
keywords: Bifurcation
keywords: Center
keywords: critical periodic orbit
keywords: criticality
keywords: Period function
abstract: The number of critical periodic orbits that bifurcate from the outer boundary of a potential center is studied. We call this number the criticality at the outer boundary. Our main results provide sufficient conditions in order to ensure that this number is exactly 0 and 1. We apply them to study the bifurcation diagram of the period function of X = −y∂ x ((x 1) p − (x 1) q )∂ y with q < p. This family was previously studied for q = 1 by Y. Miyamoto and K. Yagasaki.
file: ManRojVil2015.Preprint.pdf-d4114f1263237f3c5a3cadd13eb2ae14.pdf
</entry>
<entry>
type: Article
aigaionid: 4195
bibtexid: CarTor2016
title: Limit cycles in planar piecewise linear differential systems with nonregular separation line
author: Cardin, Pedro T.
author: Torregrosa, Joan
journal: Physica D. Nonlinear Phenomena
year: 2016
volume: 337
startpage: 67
endpage: 82
doi: 10.1016/j.physd.2016.07.008
keywords: limit cycle in Melnikov higher order perturbation
keywords: Non-smooth differential systems in two zones
keywords: nonregular separation line
abstract: In this paper we deal with lanar piecewise linear differential systems defined in two zones. We consider the case when the two linear zones are angular sectors of angles $\alpha$ and $2\pi - \alpha$, respectively, for $\alpha \in (0,\pi)$. We study the problem of determining lower bounds for the number of isolated periodic orbits in such systems using Melnikov functions. These limit cycles appear studying higher order piecewise linear perturbations of a linear center. It is proved that the maximum number of limit cycles that can appear up to a sixth order perturbation is five. Moreover, for these values of $\alpha$, we prove the existence of systems with four limit cycles up to fifth order and, for $\alpha=\pi/2,$ we provide an explicit example with five up to sixth order. In general, the nonregular separation line increases the number of periodic orbits in comparison with the case where the two zones are separated by a straight line.
file: CarTor2016.pdf-f153ead5710c7ca4b5ecfe97f74f3cf7.pdf
</entry>
<entry>
type: Article
aigaionid: 4210
bibtexid: RobSilTor2016
title: Asymptotic expansion of the heteroclinic bifurcation for the planar normal form of the 1:2 resonance
author: Roberto, Lucy Any
author: da Silva, Paulo Ricardo
author: Torregrosa, Joan
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2016
volume: 26
number: 1
startpage: 1650017 (8 pages)
doi: 10.1142/S0218127416500176
keywords: 1:2 Resonance
keywords: bifurcation diagram
keywords: Homoclinic Connections
keywords: Planar Systems
abstract: We consider the family of planar differential systems depending on two real parameters
\[\dot {x} =y,\quad \dot {y} = \delta_1 x \delta_2 y x^3-x^2y.\]
This system corresponds to the normal form for the 1:2 resonance which exhibits a heteroclinic connection. The phase portrait of the system has a limit cycle which disappears in the heteroclinic connection for the parameter values on the curve $\delta_2=c(\delta_1)=-\dfrac{1}{5}\delta_1 O(\delta_1^2),$ $\delta_1<0.$ We significantly improve the knowledge of this curve in a neighborhood of the origin.
file: RobSilTor2015.Preprint.pdf-3ece9f4f1552d23271e6891c8175612b.pdf
</entry>
<entry>
type: Article
aigaionid: 4211
bibtexid: LiLliWu2016
title: Polynomial and linearized normal forms for almost periodic differential systems
author: Li, Weigu
author: Llibre, Jaume
author: Wu, Hao
journal: Discrete and Continuous Dynamical Systems. Series A
year: 2016
volume: 36
number: 1
startpage: 345
endpage: 360
doi: 10.3934/dcds.2016.36.345
keywords: Almost periodic differential systems
keywords: Averaging theory
keywords: linearization
keywords: Normal form
file: LiLliWu2016.Preprint.pdf-48e5869f226227ec8c92a3fa8423576d.pdf
</entry>
<entry>
type: Article
aigaionid: 4212
bibtexid: LiaTor2016
title: Weak-foci of high order and cyclicity
author: Liang, Haihua
author: Torregrosa, Joan
journal: Qualitative Theory of Dynamical Systems
year: 2016
doi: 10.1007/s12346-016-0189-9
keywords: cyclicity
keywords: Lyapunov quantities
keywords: polynomial system
keywords: Weak-focus order
abstract: A particular version of the 16th Hilbert's problem is to estimate the number, $M(n),$ of limit cycles bifurcating from a singularity of center-focus type. This paper is devoted to finding lower bounds for $M(n)$ for some concrete $n$ by studying the cyclicity of different weak-foci. Since a weak-focus with high order is the most current way to produce high cyclicity, we search for systems with the highest possible weak-focus order. For even $n$, the studied polynomial system of degree $n$ was the one obtained by \cite{QiuYan2009} where the highest weak-focus order is $n^2 n-2$ for $n=4,6,\ldots, 18$. Moreover, we provide a system which has a weak-focus with order $(n-1)^2$ for $n\leq 12$. We show that Christopher's approach \cite{Chr2006}, aiming to study the cyclicity of centers, can be applied also to the weak-focus case. We also show by concrete examples that, in some families, this approach is so powerful and the cyclicity can be obtained in a simple computational way. Finally, using this approach, we obtain that $M(6)\geq 39, M(7)\geq 34$ and $M(8)\geq 63$.
file: LiaTor2015c.Preprint.pdf-427c1fc0af36bc617bf29063dc4c3eaa.pdf
</entry>
<entry>
type: Article
aigaionid: 4238
bibtexid: GouLliNovPes2016
title: Piecewise smooth dynamical systems: Persistence of periodic solutions and normal forms
author: Gouveia, Marcio R. A.
author: Llibre, Jaume
author: Novaes, Douglas D.
author: Pessoa, Claudio
journal: Journal of Differential Equations
year: 2016
volume: 260
startpage: 6108
endpage: 6129
doi: 10.1016/j.jde.2015.12.034
keywords: crossing periodic orbits
keywords: limit cycle
keywords: Lyapunov-Schmidt reduction
keywords: piecewise differential system
abstract: We consider an n-dimensional piecewise smooth vector field with two zones separated by a hyperplane $\Sigma$ which admits an invariant hyperplane $\Omega$ transversal to $\Sigma$ containing a period annulus A fulfilled by crossing periodic solutions. For small discontinuous perturbations of these systems we develop a Melnikov-like
function to control the persistence of periodic solutions contained in A. When n = 3 we provide normal forms for the piecewise linear case. Finally we apply the Melnikov-like function to study discontinuous perturbations of the given normal forms.
file: GouLliNovPes2016.Preprint.pdf-3a7fc639dcbac1fc67dde36c59ff8dfd.pdf
</entry>
<entry>
type: Article
aigaionid: 4266
bibtexid: LliPan2016
title: Limit cycles bifurcating from a degenerate center
author: Llibre, Jaume
author: Pantazi, Chara
journal: Mathematics and Computers in Simulation
year: 2016
volume: 120
startpage: 1
endpage: 11
doi: 10.1016/j.matcom.2015.05.005
keywords: Averaging theory
keywords: Centers
keywords: limit cycle
keywords: Polynomial differential systems
abstract: We study the maximum number of limit cycles that can bifurcate from a degenerate center of a cubic homogeneous polynomial differential system. Using the averaging method of second order and perturbing inside the class of all cubic polynomial differential systems we prove that at most three limit cycles can bifurcate from the degenerate center. As far as we know this is the first time that a complete study up to second order in the small parameter of the perturbation is done for studying the limit cycles which bifurcate from the periodic orbits surrounding a degenerate center (a center whose linear part is identically zero) having neither a Hamiltonian first integral nor a rational one. This study needs many computations, which have been verified with the help of the algebraic manipulator Maple.
file: LliPan2015.Preprint.pdf-c7a7a1080dd6497eb5fc4faf94337e60.pdf
</entry>
<entry>
type: Article
aigaionid: 4267
bibtexid: DukGinLli2016
title: Reversible nilpotent centers with cubic homogeneous nonlinearities
author: Dukarić, Maša
author: Giné, Jaume
author: Llibre, Jaume
journal: Journal of Mathematical Analysis and Applications
year: 2016
volume: 433
startpage: 305
endpage: 319
doi: http://dx.doi.org/10.1016/j.jmaa.2015.07.049
keywords: Nilpotent center
keywords: Phase portrait
keywords: Two dimensional differential systems
abstract: We provide 13 non-topological equivalent classes of global phase portraits in the Poincaré disk of reversible cubic homogeneous systems with a nilpotent center at origin, which complete the classification of the phase portraits of the nilpotent centers with cubic homogeneous nonlinearities.
file: DukGinLli2016.Preprint.pdf-847c42c7c64210ddd978ef939b441986.pdf
</entry>
<entry>
type: Article
aigaionid: 4271
bibtexid: BusLliGuiVer2016
title: New families of periodic orbits for a galactic potential
author: de Bustos, Maria T.
author: Llibre, Jaume
author: Guirao, Juan Luis Garcia
author: Vera, Juan A.
journal: Chaos, Solitons and Fractals
year: 2016
volume: 82
startpage: 97
endpage: 102
doi: 10.1016/j.chaos.2015.11.003
keywords: Averaging theory
keywords: family of periodic orbits
keywords: galactic potential
abstract: The Hamiltonian system associated to the Hamiltonian
\[
H=(P_1^2 P_2^2 P_3^2)/2 (Q_1^2 Q_2^2 Q_3^2)/2 \e(Q_1^4 Q_2^4 Q_3^4 a(Q_1^2Q_2^2 Q_1^2Q_3^2 Q_2^2Q_3^2)),
\]
where $\epsilon$ and $a$ are parameters and $\epsilon$ is small, describes the local motion in the central area of a galaxy. Its dynamics have been study by many authors. Here we find analytically new families of periodic orbits of this Hamiltonian system.
file: BusLliGuiVer2015.Preprint.pdf-e965974a969a5752fceb49d0f8fc3474.pdf
</entry>
<entry>
type: Article
aigaionid: 4311
bibtexid: BraGinLli2016
title: A sufficient condition in order that the Real {J}acobian Conjecture in {R}^2 holds
author: Braun, Francisco
author: Giné, Jaume
author: Llibre, Jaume
journal: Journal of Differential Equations
year: 2016
volume: 260
startpage: 5250
endpage: 5258
doi: 10.1016/j.jde.2015.12.011
keywords: centre
keywords: global injectivity
keywords: Real Jacobian conjecture
abstract: Let $F=(f,g):\R^2\to\R^2$ be a polynomial map such that $\det DF(x)$ is different from zero for all $x\in\R^2$ and $F(0,0) = (0,0)$. We prove that for the injectivity of $F$ it is sufficient
to assume that the higher homogeneous terms of the polynomials $ff_x g g_x$ and $f f_y g g_y$ do not have real linear factors in common.
file: BraGinLli2015.Preprint.pdf-cb0641c4007ff1c869087546e23bcf97.pdf
</entry>
<entry>
type: Article
aigaionid: 4316
bibtexid: TigLli2016
title: Heteroclinic, homoclinic and closed orbits in the {C}hen system
author: Tigan, Gheorghe
author: Llibre, Jaume
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2016
volume: 26
number: 4
startpage: 1650072
doi: 10.1142/S0218127416500723
keywords: bifurcations
keywords: homoclinic and heteroclinic orbits
keywords: ODE systems
abstract: Bounded orbits such as closed, homoclinic and heteroclinic orbits are discussed in this work for a Lorenz-
like 3D nonlinear system. For a large spectrum of the parameters the system has neither closed nor homoclinic orbits but has exactly two heteroclinic orbits, while under other constraints the system has symmetrical homoclinic orbits.
file: TigLli2015.Preprint.pdf-9c662aee138c1e659c277733f5643a4f.pdf
</entry>
<entry>
type: Article
aigaionid: 4317
bibtexid: CimGasMan2016
title: Periods of solutions of periodic differential equations
author: Cima, Anna
author: Gasull, Armengol
author: Mañosas, Francesc
journal: Differential and Integral Equations. An International Journal for Theory & Applications
year: 2016
volume: 29
number: 9-10
startpage: 905
endpage: 922
keywords: holomorphic differential equations
keywords: periodic differential equations
keywords: periodic orbit
abstract: Smooth non-autonomous $T$-periodic differential equations $x'(t)=f(t,x(t))$ defined in
$\R\times\K^n$, where $\K$ is $\R$ or $\C$ and $n\ge 2$ can have periodic solutions with any
arbitrary period~$S$. We show that this is not the case when $n=1.$ We prove that in the real
$\mathcal{C}^1$-setting the period of a non-constant periodic solution of the scalar differential
equation is a divisor of the period of the equation, that is $T/S\in\N.$ Moreover, we
characterize the structure of the set of the periods of all the periodic solutions of a given
equation. We also prove similar results in the one-dimensional holomorphic setting. In this
situation the period of any non-constant periodic solution is commensurable with the period of
the equation, that is $T/S\in\Q.$
file: CimGasMan2015a.Preprint.pdf-cddfdf8383643a13ec4a64a7b91cb6c9.pdf
</entry>
<entry>
type: Article
aigaionid: 4318
bibtexid: BraLliMer2016
title: Isochronicity for trivial quintic and septic planar polynomial {H}amiltonian systems
author: Braun, Francisco
author: Llibre, Jaume
author: Mereu, Ana Cristina
journal: Discrete and Continuous Dynamical Systems. Series A
year: 2016
volume: 36
number: 10
startpage: 5245
endpage: 5255
doi: 10.3934/dcds.2016029
keywords: Isochronous centers
keywords: Jacobian conjecture
keywords: polynomial Hamiltonian systems
abstract: In this paper we completely characterize trivial isochronous centers of degrees $5$ and $7$. Precisely, we provide formulas, up to linear change of coordinates, for the Hamiltonian $H$ of the isochronous centers such that $H =(f_1^2 f_2^2)/2$ has degrees $6$ and $8$, and $f = (f_1, f_2): R^2\to R^2$ is a polynomial map with $\det D f = 1$ and $f(0,0) = (0,0)$.
file: BraLliMer2015.Preprint.pdf-deba1fba9086f3c84e543925666156b0.pdf
</entry>
<entry>
type: Article
aigaionid: 4319
bibtexid: CanLli2016a
title: New results on averaging theory and applications
author: Cândido, Murilo R.
author: Llibre, Jaume
journal: ZAMP. Journal of Applied Mathematics and Physics
year: 2016
volume: 67:106
startpage: 11p.
doi: 10.1007/s00033-016-0682-7
keywords: Averaging theory
keywords: Fitzhugh--Nagumo system
keywords: Lorenz system
keywords: polynomial differential system
abstract: The usual averaging theory reduces the computation of some periodic solutions of a system of ordinary differential equations, to find the simple zeros of an associated averaged function. When one of these zeros is not simple, i.e. the Jacobian of the averaged function in it is zero, the classical averaging theory does not provide information about the periodic solution associated to a non simple zero. Here we provide sufficient conditions in order that the averaging theory can be applied also to non simple zeros for studying their associated periodic solutions. Additionally we do two applications of this new result for studying the zero--Hopf bifurcation in the Lorenz system and in the Fitzhugh--Nagumo system.
file: CanLli2015c.Preprint.pdf-6bba1907278aca45cb40087ad2c84e2a.pdf
</entry>
<entry>
type: Article
aigaionid: 4322
bibtexid: GarLliMaz2016
title: Center cyclicity of a family of quartic polynomial differential system
author: García, Isaac A.
author: Llibre, Jaume
author: Maza, Susanna
journal: NoDEA : Nonlinear Differential Equations and Applications
year: 2016
volume: 23
number: 34
startpage: 10 pages
doi: 10.1007/s00030-016-0388-8
keywords: Algebraic limit cycles
keywords: Bautin ideal
keywords: Center
keywords: cyclicity
keywords: Polynomial vector fields
abstract: In this paper we study the cyclicity of the centers of the quartic polynomial family written in complex notation as
\[\dot{z} = i z z \bar{z} (A z^2 B z \bar{z} C \bar{z}^2 ),\]
where $A,B,C \in \mathbb{C}$. We give an upper bound for the cyclicity of any nonlinear center at the origin when we perturb it inside this family. Moreover we prove that this upper bound is sharp.
file: GarLliMaz2015.Preprint.pdf-7eac23dd52604f3d158bc04b7ca83ddc.pdf
</entry>
<entry>
type: Article
aigaionid: 4324
bibtexid: Lli2016a
title: Centers: their integrability and relations with the divergence
author: Llibre, Jaume
journal: Applied Mathematics and Nonlinear Sciences
year: 2016
volume: 1
number: 1
startpage: 79
endpage: 86
doi: 10.21042/AMNS.2016.1.00007
keywords: Center problem
keywords: divergence
keywords: integrability
keywords: Poincar\'e--Liapunov constants
abstract: This is a brief survey on the centers of the analytic differential systems in $\mathbb {R}^2$. First we consider the kind of integrability of the different types of centers, and after we analyze the focus--center problem, i.e. how to distinguish a center from a focus. This is a difficult problem which is not completely solved. We shall present some recent results using the divergence of the
differential system.
file: Lli2015b.Preprint.pdf-e55c7f11b77e6aaf00edb45a9ad83259.pdf
</entry>
<entry>
type: Article
aigaionid: 4328
bibtexid: LliZha2016
title: Limit cycles of linear vectors on manifolds
author: Llibre, Jaume
author: Zhang, Xiang
journal: Nonlinearity
year: 2016
volume: 29
startpage: 3120
endpage: 3131
doi: 10.1088/0951-7715/29/10/3120
keywords: averaging method
keywords: Center
keywords: Isochronous center
keywords: limit cycle
keywords: periodic orbit
abstract: It is well known that linear vector fields on the manifold $R^n$ cannot have limit cycles, but this is not the case for linear vector fields on other manifolds. We study the periodic orbits of linear vector fields on different manifolds, and motivate and present an open problem on the number of limit cycles of linear vector fields on a class of $C^1$ connected manifold.
file: LliZha2015.Preprint.pdf-74f06358733d3c20e9c52922c6165821.pdf
</entry>
<entry>
type: Article
aigaionid: 4331
bibtexid: GasLloMan2015
title: Continua of periodic points for planar integrable rational maps
author: Gasull, Armengol
author: Llorens, Mireia
author: Mañosa, Víctor
journal: International Journal of Difference Equations
year: 2016
volume: 11
number: 1
startpage: 37
endpage: 63
keywords: birational maps
keywords: Integrable rational maps
keywords: periodic orbits
abstract: We present three alternative methodologies to find continua of
periodic points with a prescribed period for rational maps having
rational first integrals. The first two have been already used for
other authors and apply when the maps are birational and the
generic level sets of the corresponding first integrals have either
genus 0 or 1. As far as we know, the third one is new and it works
for rational maps without imposing topological properties to the
invariant level sets. It is based on a computational point of view,
and relies on the use of resultants in a suitable setting. We apply
them to several examples, including the 2-periodic Lyness
composition maps and some of the celebrated McMillan-Gumowski-Mira
maps.
file: GasLloMan2015.Preprint.pdf-700baa676e6ddeb13d5f4ecf7db32bfd.pdf
</entry>
<entry>
type: Article
aigaionid: 4332
bibtexid: LliVal2016b
title: On the analytic integrability of the Liénard analytic differential systems
author: Llibre, Jaume
author: Valls, Clàudia
journal: Discrete and Continuous Dynamical Systems. Series B
year: 2016
volume: 21
number: 2
startpage: 557
endpage: 573
doi: 10.3934/dcdsb.2016.21.557
keywords: analytic integrability
keywords: Formal integrability
keywords: Li\'{e}nard system
abstract: We consider the Li\'{e}nard analytic differential systems $\dot x = y$, $\dot y =-g(x) -f(x)y$, where $f,g: \mathbb {R} \to \mathbb {R}$ are analytic functions and the origin is an isolated singular point. Then for such systems we characterize the existence of local analytic first integrals in a neighborhood of the origin and the existence of global analytic first integrals.
file: LliVal2016b.Preprint.pdf-08e6edec320aaf2c995c7335d06c5239.pdf
</entry>
<entry>
type: Article
aigaionid: 4345
bibtexid: GinLliWuZha2016
title: Averaging methods of arbitrary order, periodic solutions and integrability
author: Giné, Jaume
author: Llibre, Jaume
author: Wu, Kesheng
author: Zhang, Xiang
journal: Journal of Differential Equations
year: 2016
volume: 260
startpage: 4130
endpage: 4156
doi: 10.1016/j.jde.2015.11.005
keywords: averaging method
keywords: Differential systems
keywords: integrability
keywords: limit cycle
keywords: Polynomial differential systems
abstract: In this paper we provide an arbitrary order averaging theory for higher dimensional periodic analytic differential systems. This result extends and improves results on averaging theory of periodic analytic differential systems, and it unifies many different kinds of averaging methods. Applying our theory to autonomous analytic differential systems, we obtain some conditions on the existence of limit cycles and integrability. For polynomial differential systems with a singularity at the origin having a pair of pure imaginary eigenvalues, we prove that there always exists a positive number N such that if its first N averaging functions vanish, then all averaging functions vanish, and consequently there exists a neighborhood of the origin filled with periodic orbits. Consequently if all averaging functions vanish, the origin is a center for n = 2. Furthermore, in a punctured neighborhood of the origin, the system is $C^\infty$ completely integrable for n > 2 provided that each periodic orbit has a trivial holonomy. Finally we develop an averaging theory for studying limit cycle bifurcations and the integrability of planar polynomial differential systems near a nilpotent monodromic singularity and some degenerate monodromic singularities.
file: GinLliWuZha2016.Preprint.pdf-213695c57efea43381c7f70f414b5755.pdf
</entry>
<entry>
type: Article
aigaionid: 4361
bibtexid: GasGeyMan2016
title: On the number of limit cycles for perturbed pendulum equations
author: Gasull, Armengol
author: Geyer, Anna
author: Mañosas, Francesc
journal: Journal of Differential Equations
year: 2016
volume: 261
number: 3
startpage: 2141
endpage: 2167
doi: 10.1016/j.jde.2016.04.025
keywords: Abelian integrals
keywords: Infinitesimal Sixteenth Hilbert problem
keywords: limit cycles
keywords: Perturbed pendulum equation
abstract: We consider perturbed pendulum-like equations on the cylinder of the form $ \ddot x \sin(x)= \varepsilon \sum_{\s=0}^{m}{Q_{n,\s} (x)\, \dot x^{\s}}$ where $Q_{n,\s}$ are trigonometric polynomials of degree $n$, and study the number of limit cycles that bifurcate from the periodic orbits of the unperturbed case $\varepsilon=0$ in terms of $m$ and $n$. Our first result gives upper bounds on the number of zeros of its associated first order Melnikov function, in both the oscillatory and the rotary regions. These upper bounds are obtained expressing the corresponding Abelian integrals in terms of polynomials and the complete elliptic functions of first and second kind. Some further results give sharp bounds on the number of zeros of these integrals by identifying subfamilies which are shown to be Chebyshev systems.
file: GasGeyMan2016.Preprint.pdf-860fcde78c91533201dd7f659bd02a3b.pdf
</entry>
<entry>
type: Article
aigaionid: 4363
bibtexid: DiaLliMel2016
title: When parallels and meridians are limit cycles for polynomial vector fields on quadrics of revolution in the euclidean 3-space
author: Dias, Fabio Scalco
author: Llibre, Jaume
author: Mello, Luis Fernando
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2016
volume: 26
number: 9
startpage: 1650160 (14 pages)
doi: 10.1142/S0218127416501601
keywords: invariant meridian
keywords: invariant parallel
keywords: limit cycle
keywords: periodic orbit
keywords: Polynomial vector field
abstract: We study polynomial vector fields of arbitrary degree in ${R}^3$ with an invariant quadric of revolution. We characterize all the possible configurations of invariant meridians and parallels that these vector fields can exhibit. Furthermore we analyze when these invariant meridians and parallels can be limit cycles.
file: DiaLliMel2016.preprint.pdf-b9a9e6f7035353b6aa6e5e1e8979f3e2.pdf
</entry>
<entry>
type: Article
aigaionid: 4368
bibtexid: GasTorZha2016
title: The number of polynomial solutions of polynomial {R}iccati equations
author: Gasull, Armengol
author: Torregrosa, Joan
author: Zhang, Xiang
journal: Journal of Differential Equations
year: 2016
volume: 261
startpage: 5071
endpage: 5093
doi: 10.1016/j.jde.2016.07.019
keywords: explicit solutions
keywords: number of polynomial solutions
keywords: Polynomial differential equations
keywords: Riccati differential equations
keywords: trigonometric polynomial differential equations
abstract: Consider real or complex polynomial Riccati differential equations $a(x) \dot y=b_0(x) b_1(x)y b_2(x)y^2$ with all the involved functions being polynomials of degree at most $\eta$. We prove that the maximum number of polynomial solutions is $\eta 1$ (resp. 2) when $\eta\ge 1$ (resp. $\eta=0$) and that these bounds are sharp.

For real trigonometric polynomial Riccati differential equations with all the functions being trigonometric polynomials of degree at most $\eta\ge 1$ we prove a similar result. In this case, the maximum number of trigonometric polynomial solutions is $2\eta$ (resp. $3$) when $\eta\ge 2$ (resp. $\eta=1$) and, again, these bounds are sharp.

Although the proof of both results has the same starting point, the classical result that asserts that the cross ratio of four different solutions of a Riccati differential equation is constant, the trigonometric case is much more involved. The main reason is that the ring of trigonometric polynomials is not a unique factorization domain.
file: GasTorZha2016.Preprint.pdf-6605adc2f582d8c93dc0789942e9aaaf.pdf
</entry>
<entry>
type: Article
aigaionid: 4377
bibtexid: GinLli2016
title: Canards Existence in {M}emristor’s Circuits
author: Ginoux, Jean-Marc
author: Llibre, Jaume
journal: Qualitative Theory of Dynamical Systems
year: 2016
doi: 10.1007/s12346-015-0160-1
keywords: canard solutions
keywords: Geometric singular perturbation theory
keywords: singularly perturbed dynamical systems
abstract: The aim of this work is to propose an alternative method for determining the condition of existence of “canard solutions” for three and four-dimensional singularly perturbed systems with only one fast variable in the folded saddle case. This method enables to state a unique generic condition for the existence of “canard solutions”
for such three and four-dimensional singularly perturbed systems which is based on the stability of folded singularities of the normalized slow dynamics deduced from a well-known property of linear algebra. This unique generic condition is perfectly identical to that provided in previous works. Application of this method to the famous
three and four-dimensional memristor canonical Chua’s circuits for which the classical piecewise-linear characteristic curve has been replaced by a smooth cubic nonlinear function according to the least squares method enables to show the existence of “canard solutions” in such Memristor Based Chaotic Circuits.
file: GinLli2016.Preprint.pdf-a6e9df675365ff2aa99a640a913ffbdc.pdf
</entry>
<entry>
type: Article
aigaionid: 4383
bibtexid: CanFagGar2016
title: Tongues in Degree 4 {B}laschke Products
author: Canela, Jordi
author: Fagella, Nuria
author: Garijo, Antoni
journal: Nonlinearity
year: 2016
volume: 29
startpage: 3464
endpage: 3495
doi: 10.1088/0951-7715/29/11/3464
keywords: Blaschke products
keywords: circle maps
keywords: Holomorphic dynamics
keywords: tongues
abstract: The goal of this paper is to investigate the family of Blasche products $B_a(z)=z^3\frac{z-a}{1-\bar{a}z}$, which is a rational family of perturbations of the doubling map. We focus on the tongue-like sets which appear in its parameter plane. We first study their basic topological properties and afterwords we investigate how bifurcations take place in a neighborhood of their tips. Finally we see how the period one tongue extends beyond its natural domain of definition.
file: CanFagGar2016.preprint.pdf-bd18cbb0a111c36b82848aa919e1e360.pdf
</entry>
<entry>
type: Article
aigaionid: 4388
bibtexid: AlsManMor2016
title: A quasiperiodically forced skew-product on the cyclinder without fixed-curves
author: Alsedà, Lluís
author: Mañosas, Francesc
author: Morales, Leopoldo
journal: Nonlinear Analysis. Theory, Methods & Applications. An International Multidisciplinary Journal. Series A: Theory and Methods
year: 2016
volume: 145
startpage: 199
endpage: 263
keywords: invariant strips
keywords: Quasiperiodically forced systems on the cylinder
abstract: In [FJJK] the Sharkovski\uı Theorem was extended to periodic orbits of strips of quasiperiodic skew products in the cylinder. In this paper we deal with the following natural question that arises in this setting: Does Sharkovski\uı Theorem holds when restricted to curves instead of general strips? We answer this question in the negative by constructing a counterexample: We construct a map having a periodic orbit of period 2
of curves (which is, in fact, the upper and lower circles of the cylinder) and without any invariant curve. In particular this shows that there exist quasiperiodic skew products in the cylinder without invariant curves.

[FJJK] Roberta Fabbri, Tobias Jäger, Russell Johnson, and Gerhard Keller. A {S}harkovskii-type theorem for minimally forced interval maps. Topol. Methods Nonlinear Anal., 26(1):163--188, 2005.
file: AlsManMor2016.Preprint.pdf-87ff42b7a5d80dbdc1cc0682322dd765.pdf
</entry>
<entry>
type: Article
aigaionid: 4390
bibtexid: CamGarJarVin2016
title: Newton's method for symmetric quartic polynomials
author: Campos, Beatriz
author: Garijo, Antoni
author: Jarque, Xavier
author: Vindel, Pura
journal: Applied Mathematics and Computation
year: 2016
volume: 290
startpage: 326
endpage: 335
doi: 10.1016/j.amc.2016.06.021
keywords: Holomorphic dynamics
keywords: Julia and Fatou sets
keywords: Newton’s method
abstract: We investigate the parameter plane of the Newton's method applied to the family of quartic polynomials
$p_{a,b}(z)=z^4 az^3 bz^2 az 1$, where $a$ and $b$ are real parameters. We divide the parameter plane
$(a,b) \in \mathbb R^2$ into twelve open and connected {\it regions} where $p$, $p'$ and $p''$ have
simple roots. In each of these regions we focus on the study of the Newton's operator acting on the Riemann sphere.
file: CAMGARJARVIN2016.pdf-ab9aec38243579caca6b620f7d00cec2.pdf
</entry>
<entry>
type: Article
aigaionid: 4402
bibtexid: GuiLli2016a
title: Periods of continuous maps on some compact spaces
author: Guirao, Juan Luis Garcia
author: Llibre, Jaume
journal: Houston Journal of Mathematics
year: 2016
volume: 42
number: 3
startpage: 1047
endpage: 1058
keywords: complex projective space
keywords: continuous map
keywords: Lefschetz fixed point theory
keywords: periodic point
keywords: Periods
keywords: product of two spheres
keywords: quaternion projective space
keywords: sphere
abstract: The objective of this paper is to provide information on the set of periodic points of a continuous self--map defined in the following compact spaces: $\mathbb{S}^{n}$ (the $n$--dimensional sphere), $\mathbb{S}^{n}\times \mathbb{S}^{m}$ (the product space of the $n$--dimensional with the $m$--dimensional spheres), $\mathbb{C}P^{n}$ (the $n$--dimensional complex projective space) and $\mathbb{H}P^{n}$ (the $n$--dimensional quaternion projective space). We use as main tool the action of the map on the homology groups of these compact spaces.
file: GuiLli2016a.preprint.pdf-4fb13ac063abea42ab66d5c85081f2c6.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4410
bibtexid: Mor2016
title: Combinatorial dynamics of strip patterns of quasiperiodic skew products in the cylinder
author: Morales, Leopoldo
year: 2016
school: Universitat Autònoma de Barcelona
address: Bellaterra
file: Mor2016.pdf-d9e415f7c08d549434ad7cbbf4d51cb3.pdf
</entry>
<entry>
type: Phdthesis
aigaionid: 4415
bibtexid: Roj2016
title: Analytical tools to study the criticality at the outer boundary of potential centers
author: Rojas, David
year: 2016
school: Universitat Autònoma de Barcelona
address: Bellaterra
file: Roj2016.pdf-413201363d3d731a45afd08bc9b2fdef.pdf
</entry>
<entry>
type: Article
aigaionid: 4426
bibtexid: BujLliVul2016
title: First integrals and phase portraits of planar polynomial differential cubic systems with the maximum number of invariant straight lines
author: Bujac, Cristina
author: Llibre, Jaume
author: Vulpe, Nicolae
journal: Qualitative Theory of Dynamical Systems
year: 2016
volume: 15
startpage: 327
endpage: 348
abstract: In the article LliVul2006 the family of cubic polynomial
differential systems possessing invariant straight lines of total
multiplicity 9 was considered and 23 such classes of systems were
detected. We recall that 9 invariant straight lines taking into
account their multiplicities is the maximum number of straight
lines that a cubic polynomial differential systems can have if
this number is finite. Here we complete the classification given
in LliVul2006 by adding a new class of such cubic
systems and for each one of these 24 such classes we perform the
corresponding first integral as well as its phase portrait.
Moreover we present necessary and sufficient affine invariant
conditions for the realization of each one of the detected classes
of cubic systems with maximum number of invariant straight lines
when this number is finite.
file: BujLliVul2016.preprint.pdf-150014e6d7de07650cee7089931f2903.pdf
</entry>
<entry>
type: Article
aigaionid: 4427
bibtexid: GinLli2016d
title: Analytic reducibility of nondegenerate centers: {C}herkas systems
author: Giné, Jaume
author: Llibre, Jaume
journal: Electronic Journal of Qualitative Theory of Differential Equations
year: 2016
volume: 49
startpage: 1
endpage: 10
doi: doi: 10.14232/ejqtde.2016.1.49
keywords: analytic integrability
keywords: Center problem
keywords: polynomial Cherkas differential systems
file: GinLli2016d.preprint.pdf-2a85970dc88a865ec8937a739c65a69c.pdf
</entry>
<entry>
type: Article
aigaionid: 4436
bibtexid: LliVid2016
title: Hopf periodic orbits for a ratio-dependent predator-prey model with stage structure
author: Llibre, Jaume
author: Vidal, Claudio
journal: Discrete and Continuous Dynamical Systems. Series B
year: 2016
volume: 21
number: 6
startpage: 1859
endpage: 1867
doi: 10.3934/dcdsb.2016026
keywords: Averaging theory
keywords: Hopf bifurcation
keywords: predator-prey model
keywords: Ratio–dependence
abstract: A ratio–dependent predator-prey model with stage structure for prey was investigated in [8]. There the authors mentioned that they were unable to show if such a model admits limit cycles when the unique equilibrium
point E ∗ at the positive octant is unstable. Here we characterize the existence of Hopf bifurcations for the systems. In particular we provide a positive answer to the above question showing for such models the existence of small–amplitude Hopf limit cycles being the equilibrium point E ∗ unstable.
file: LliVid2016.preprint.pdf-4a5e2c879f1585724c566f0cfe16fdc6.pdf
</entry>
<entry>
type: Article
aigaionid: 4444
bibtexid: LemLli2016a
title: Periodic orbits of perturbed elliptic oscillators in 6{D} via averaging theory
author: Lembarki, Fatima E.
author: Llibre, Jaume
journal: Astrophysics and Space Science. An International Journal of Astronomy, Astrophysics and Space Science
year: 2016
startpage: 361
endpage: 340
doi: 10.1007/s10509-016-2930-x
keywords: Averaging theory
keywords: galactic dynamics
keywords: periodic orbits
keywords: perturbed elliptic oscillators
abstract: We provide sufficient conditions on the energy levels to guarantee
the existence of periodic orbits for the perturbed elliptic
oscillators in 6D using the averaging theory. We give also an
analytical estimation of the shape of these periodic orbits
parameterized by the energy. The Hamiltonian system here studied
comes either from the analyze of the galactic dynamics, or from the
motion of the atomic particles in physics.
file: LemLli2016a.preprint.pdf-c81eeb200fb545fba26546e90c030b0e.pdf
</entry>
<entry>
type: Article
aigaionid: 4471
bibtexid: OsRebVi2016
title: On a Class of Invariant Algebraic Curves for {K}ukles Systems
author: Osuna, Osvaldo
author: Rebollo-Perdomo, Salomón
author: Villaseñor, Gabriel
journal: Electronic Journal of Qualitative Theory of Differential Equations
year: 2016
volume: 2016
number: 61
startpage: 1
endpage: 12
doi: 10.14232/ejqtde.2016.1.61
keywords: invariant curve
keywords: Kukles system
file: OsRebVi2016.Preprint.pdf-e84e4789358c014f4e02cba9e622174d.pdf
</entry>
<entry>
type: Article
aigaionid: 4487
bibtexid: ArtOliRez2016
title: Topological Classification of Quadratic Polynomial Differential Systems with a Finite Semi-Elemental Triple Saddle
author: Artés, Joan Carles
author: Oliveira, Regilene D. S.
author: Rezende, Alex Carlucci
journal: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering
year: 2016
volume: 26
number: 11
startpage: 1650188 (26 pages)
doi: 10.1142/S0218127416501881
keywords: algebraic invariants
keywords: bifurca- tion diagram
keywords: phase portraits
keywords: Quadratic differential systems
keywords: semi-elemental triple saddle
abstract: The study of planar quadratic differential systems is very important not only because they appear in many areas of applied mathematics but due to their richness in structure, stability and questions concerning limit cycles, for example. Even though many papers have been written on this class of systems, a complete understanding of this family is still missing. Classical problems, and in particular Hilbert’s 16th problem [Hilbert, 1900, 1902], are still open for this family. In this article, we make a global study of the family QTS of all real quadratic polynomial differential systems which have a finite semi-elemental triple saddle (triple saddle with exactly one zero eigenvalue). This family modulo the action of the affine group and time homotheties is three-dimensional and we give its bifurcation diagram with respect to a normal form, in the three-dimensional real space of the parameters of this normal form. This bifur- cation diagram yields 27 phase portraits for systems in QTS counting phase portraits with and without limit cycles. Algebraic invariants are used to construct the bifurcation set and we present the phase portraits on the Poincar ́e disk. The bifurcation set is not just algebraic due to the presence of a surface found numerically, whose points correspond to connections of separatrices.
file: ArtOliRez2016.preprint.pdf-e2b019d666cd1a6f8219d7ebfb9553b1.pdf
</entry>
<entry>
type: Article
aigaionid: 3652
bibtexid: AlsJuhMan2017
title: On the minimum positive entropy for cycles on trees
author: Alsedà, Lluís
author: Juher, David
author: Mañosas, Francesc
journal: Transactions of the American Mathematical Society
year: 2017
volume: 369
number: 1
startpage: 187
endpage: 221
file: AlsJuhMan2013.pdf-e8f2700425b79d14a2d915c9ad096a60.pdf
</entry>
<entry>
type: Article
aigaionid: 4330
bibtexid: BenLli2017
title: Centers and limit cycles of polynomial differential systems of degree 4 via averaging theory
author: Benterki, Rebiha
author: Llibre, Jaume
journal: Journal of Computational and Applied Mathematics
year: 2017
volume: 313
startpage: 273
endpage: 283
doi: 10.1016/j.cam.2016.08.047
keywords: averaging method
keywords: Center
keywords: generalized Kukles system
keywords: limit cycle
keywords: Phase portrait
abstract: In this paper we classify the phase portraits in the Poincar\'{e} disc of the centers of the generalized class of Kukles systems \[ \dot{x}=-y,\quad\dot{y}=x ax^3y bxy^3, \] symmetric with respect to the $y$-axis, and we study, using the averaging theory up to sixth order, the limit cycles which bifurcate from the periodic solutions of these centers when we perturb them inside the class of all polynomial differential systems of degree $4$.
file: BenLli2015.Preprint.pdf-4de0dae45f675df249a2b3ed575db59d.pdf
</entry>
<entry>
type: Article
aigaionid: 4393
bibtexid: ArtItiLli2017
title: Uniform isochronous cubic and quartic centers: {R}evisited
author: Artés, Joan Carles
author: Itikawa, Jackson
author: Llibre, Jaume
journal: Journal of Computational and Applied Mathematics
year: 2017
volume: 313
startpage: 448
endpage: 453
keywords: periodic orbit
keywords: Polynomial vector field
keywords: uniform isochronous center
abstract: In this paper we completed the classification of the phase portraits in the Poincaré disc of uniform isochronous cubic and quartic centers previously studied by several authors. There are three and fourteen different topological phase portraits for the uniform isochronous cubic and quartic centers respectively.
file: ArtItiLli2016.preprint.pdf-8b4be3671a1e4bf72fcb2804d30fe952.pdf
</entry>
<entry>
type: Article
aigaionid: 4435
bibtexid: BuzPazPer2017
title: Center boundaries for planar piecewise-smooth differential equations with two zones
author: Buzzi, Claudio Aguinaldo
author: Pazim, Rubens
author: Pérez-González, Set
journal: Journal of Mathematical Analysis and Applications
year: 2017
volume: 445
startpage: 631
endpage: 649
doi: 10.1016/j.jmaa.2016.07.022
keywords: limit cycle
keywords: non-smooth differential system
keywords: Piecewise linear differential system
abstract: This paper is concerned with 1-parameter families of periodic solutions of piecewise smooth planar vector fields, when they behave like a center of smooth vector fields. We are interested in finding a separation boundary for
a given pair of smooth systems in such a way that the discontinuous system, formed by the pair of smooth systems, has a continuum of periodic orbits. In this case we call the separation boundary as a center boundary. We prove that given a pair of systems that share a hyperbolic focus singularity p 0 , with the same orientation and opposite stability, and a ray Σ 0 with endpoint at the singularity p 0 , we can find a smooth manifold Ω such that Σ 0 ∪ {p 0 } ∪ Ω is a center boundary. The maximum number of such manifolds satisfying these conditions is five. Moreover, this upper bound is reached.
file: BuzPazPer2016.Preprint.pdf-0344f3e8ae0d57bf70d7fe1b9afbfb19.pdf
</entry>

    (1-1/1)