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Periodic solutions for periodic second-order differential equations with variable potentials

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Published/Copyright: November 6, 2018

Abstract

We provide sufficient conditions for the existence of periodic solutions of the second-order differential equation with variable potentials -(px)(t)-r(t)p(t)x(t)+q(t)x(t)=f(t,x(t)), where the functions p(t)>0, q(t), r(t) and f(t,x) are 𝒞2 and T-periodic in the variable t.

MSC 2010: 37G15; 37C80; 37C30

Funding statement: The first author is partially supported by a MICINN/FEDER grant number MTM2009-03437, by an AGAUR grant number 2009SGR-410, by an ICREA Academia, two FP7+PEOPLE+2012+IRSES numbers 316338 and 318999, and FEDER-UNAB10-4E-378.

A Appendix: Averaging theory of first order

In this appendix, we recall one of the basic results from the averaging theory that we need for proving the main results of this paper.

We consider the problem of the bifurcation of T-periodic solutions from differential systems of the form

(A.1)𝐱=F0(t,𝐱)+εF1(t,𝐱)+ε2F2(t,𝐱,ε)

with ε=0 to ε0 sufficiently small. Here the functions F0,F1:×Ωn and F2:×Ω×(-ε0,ε0)n are 𝒞2 functions, T-periodic in the first variable, and Ω is an open subset of n. The main assumption is that the unperturbed system

(A.2)𝐱=F0(t,𝐱)

has a submanifold of dimension n of periodic solutions. A solution of this problem is given using the averaging theory.

Let 𝐱(t,𝐳,ε) be the solution of system (A.2) such that 𝐱(0,𝐳,ε)=𝐳. We write the linearization of the unperturbed system along the periodic solution 𝐱(t,𝐳,0) as

(A.3)𝐲=D𝐱F0(t,𝐱(t,𝐳,0))𝐲,

where 𝐲 is an n×n matrix. In what follows, we denote by M𝐳(t) some fundamental matrix of the linear differential system (A.3).

We assume that there exists an open set V with Cl(V)Ω such that, for each 𝐳Cl(V), 𝐱(t,𝐳,0) is T-periodic. The set Cl(V) is isochronous for the system (A.1); i.e., it is a set formed only by periodic orbits, all of them having the same period. Then an answer to the problem of the bifurcation of T-periodic solutions from the periodic solutions 𝐱(t,𝐳,0) contained in Cl(V) is given in the following result.

Theorem 2 (Perturbations of an isochronous set).

We assume that there exists an open and bounded set V with Cl(V)Ω such that, for each zCl(V), the solution x(t,z,0) is T-periodic. Then we consider the function F:Cl(V)Rn,

(A.4)(𝐳)=0TM𝐳-1(t)F1(t,𝐱(t,𝐳,0))dt.

If there exists αV with F(α)=0 and

(A.5)det((d/d𝐳)(𝐳*))0,

then there exists a T-periodic solution x(t,ε) of system (A.1) such that, when ε0, we have x(0,ε)α.

Theorem 2 goes back to Malkin [7] and Roseau [8]; for a shorter and easier proof, see [4].

Acknowledgements

We thank the reviewer for his/her comments.

References

[1] M. Abramowitz and I. A. Stegun, Modified Bessel functions. I and K §9.6, Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, New York, Dover (1972), 374–377. Search in Google Scholar

[2] D. R. Anderson, Multiple periodic solutions for a second-order problem on periodic time scales, Nonlinear Anal. 60 (2005), no. 1, 101–115. 10.1016/S0362-546X(04)00338-4Search in Google Scholar

[3] D. R. Anderson and R. I. Avery, Existence of a periodic solution for continuous and discrete periodic second–order equations with variable potentials, J. Appl. Math. Comput. 37 (2011), 297–312. 10.1007/s12190-010-0435-2Search in Google Scholar

[4] A. Buica, J. P. Françoise and J. Llibre, Periodic solutions of nonlinear periodic differential systems with a small parameter, Commun. Pure Appl. Anal. 6 (2006), 103–111. 10.3934/cpaa.2007.6.103Search in Google Scholar

[5] J. R. Graef, L. Kong and H. Wang, Existence, multiplicity, and dependence on a parameter for a periodic boundary value problem, J. Differential Equations 245 (2008), 1185–1197. 10.1016/j.jde.2008.06.012Search in Google Scholar

[6] Y. Liu, W. Ge and Z. Gui, Three positive periodic solutions of nonlinear differential equations with periodic coefficients, Anal. Appl. 3 (2005), no. 2, 145–155. 10.1142/S0219530505000546Search in Google Scholar

[7] I. G. Malkin, Some Problems of the Theory of Nonlinear Oscillations (in Russian), Gosudarstv. Izdat. Tehn-Teor. Lit., Moscow, 1956. Search in Google Scholar

[8] M. Roseau, Vibrations non linéaires et théorie de la stabilité, Springer Tracts Nat. Philos. 8, Springer, New York, 1985. Search in Google Scholar

Received: 2017-10-12
Revised: 2018-02-02
Accepted: 2018-02-05
Published Online: 2018-11-06
Published in Print: 2018-12-01

© 2018 Walter de Gruyter GmbH, Berlin/Boston

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