Dr. Uribe-Santibañez, Marco

We consider a completely integrable system of differential equations in arbitrary dimensions whose phase space contains an open set foliated by periodic orbits. This research analyzes the persistence and stability of the periodic orbits under a nonlinear periodic perturbation. For this purpose, we use the Melnikov method and Floquet theory to establish conditions for the existence and stability of periodic orbits. Our approach considers periods of the unperturbed orbits depending on the integrals and constant periods. In the applications, we deal with both cases. Precisely, we study the existence of periodic orbits in a perturbed generalized Euler system. In the degenerate case, we analyze the existence and stability of periodic orbits for a perturbed harmonic oscillator.

In this paper we consider the autonomous Hamiltonian system with two degrees of freedom associated to the function H = ½ (x2 + y2) + ½ (p2/x + p2/y) + V5(x, y), where V5(x, y) = (A/5x5 + Bx3y2 + C/5 xy4) which is related to a homogeneous potential of degree five. We prove the existence of different families of periodic orbits and the type of stability is analyzed through the averaging theory which guarantee the existence of such orbits on adequate sets defined by the parameters A, B, C.

We consider the Hamiltonian polynomial function H of degree fourth given by either H(x,y,{p_x},{p_y}) = \frac{1}{2}(p_x^2 + p_y^2) + \frac{1}{2}({x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y),\,\,{\text{or}}\,H(x,y,{p_x},{p_y}) = \frac{1}{2}( - p_x^2 + p_y^2) + \frac{1}{2}( - {x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y), where V3(x,y) and V4(x,y) are homogeneous polynomials of degree three and four, respectively. Our main objective is to prove the existence and stability of periodic solutions associated to H using the classical averaging method.