Symmetric Homoclinic Orbits at the Periodic Hamiltonian Hopf Bifurcation

We prove the existence of symmetric homoclinic orbits to a saddle-focus symmetric periodic orbit that appears in a generic family of reversible three degrees of freedom Hamiltonian system due to periodic Hamiltonian Hopf bifurcation, if some coefficient A of the normal form of the fourth order is positive. If this coefficient is negative, then for the opposite side of the bifurcation parameter value, we prove the existence of symmetric homoclinic orbits to saddle invariant 2-tori.

Analysis of the Frictional Vibration of a Cleaning Blade in Laser Printers Based on a Two-Degree-Of-Freedom Model

This research aims to analyze the dynamics of the self-excited vibration of a cleaning blade in a laser printer. First, it is experimentally indicated that that the self-excited vibration is not caused by the negative damping effect based on friction. Next, the excitation mechanism and dynamics of the vibration are theoretically clarified using an essential 2DOF link model, with emphasis placed on the contact between the blade and the photoreceptor. By solving the equations governing the motion of the analytical model, five patterns of static equilibrium states are obtained, and the effect of friction on the static states is discussed. It is shown that one of five patterns corresponds to the shape of the practical cleaning blade, and it is clarified through linear stability analysis that this state becomes dynamically unstable, due to both effects of friction and mode coupling. Furthermore, the amplitude of the vibration in the unstable region is determined through nonlinear analysis. The obtained results show that this unstable vibration is a bifurcation classified as a supercritical Hamiltonian-Hopf bifurcation, and confirms the occurrence of mode-coupled self-excited vibration on a cleaning blade when a constant frictional coefficient is assumed.

THE STRUCTURE AND EVOLUTION OF CONFINED TORI NEAR A HAMILTONIAN HOPF BIFURCATION

We study the orbital behavior at the neighborhood of complex unstable periodic orbits in a 3D autonomous Hamiltonian system of galactic type. At a transition of a family of periodic orbits from stability to complex instability (also known as Hamiltonian Hopf Bifurcation) the four eigenvalues of the stable periodic orbits move out of the unit circle. Then the periodic orbits become complex unstable. In this paper, we first integrate initial conditions close to the ones of a complex unstable periodic orbit, which is close to the transition point. Then, we plot the consequents of the corresponding orbit in a 4D surface of section. To visualize this surface of section we use the method of color and rotation [Patsis & Zachilas, 1994]. We find that the consequents are contained in 2D "confined tori". Then, we investigate the structure of the phase space in the neighborhood of complex unstable periodic orbits, which are further away from the transition point. In these cases we observe clouds of points in the 4D surfaces of section. The transition between the two types of orbital behavior is abrupt.