On the behavior of periodic solutions of planar autonomous Hamiltonian systems with multivalued periodic perturbations

Aim of the paper is to provide a method to analyze the behavior of $T$-periodic solutions x_\eps, \eps>0, of a perturbed planar Hamiltonian system near a cycle $x_0$, of smallest period $T$, of the unperturbed system. The perturbation is represented by a $T$-periodic multivalued map which vanishes as \eps\to0. In several problems from nonsmooth mechanical systems this multivalued perturbation comes from the Filippov regularization of a nonlinear discontinuous $T$-periodic term. \noindent Through the paper, assuming the existence of a $T$-periodic solution x_\eps for \eps>0 small, under the condition that $x_0$ is a nondegenerate cycle of the linearized unperturbed Hamiltonian system we provide a formula for the distance between any point $x_0(t)$ and the trajectories x_\eps([0,T]) along a transversal direction to $x_0(t).

Viable solutions of differential inclusions with memory in Banach spaces

In this paper we study functional differential inclusions with memory and state constraints. We assume the state space to be a separable Banach space and prove existence results for an upper semicontinuous orientor field; we consider both the case of a globally measurable orientor field and the case of a Caratheodory one

Existence and multiplicity of heteroclinic solutions for non-autonomous boundary eigenvalue problem

In this paper we investigate the boundary eigenvalue problem x''-b(c,t,x)x'+g(t,x)=0, x(-∞)=0, x(+∞)=1 depending on the real parameter c. We take the function b continuous and positive and assume that g is bounded and becomes active and positive only when it exceeds a threshold value theta in (0,1). At the point theta we allow g to have a jump. Additional monotonicity properties are required, when needed. Our main discussion deals with the non-autonomous case. In this context we prove the existence of a continuum of values for which this problem is solvable and we estimate the interval of such admissible values. In the autonomous case, we show its solvability for at most one c*. In the special case when b=c+h(x) with h continuous, we also give a non-existence result, for any real c. Our methods combine comparison-type arguments, both for first and second order dynamics, with a shooting technique. Some applications of the obtained results are included

Heteroclinic Orbits in Plane Dynamical Systems

We consider general second order boundary value problems on the whole line of the type u''=h(t, u, u'), u(-∞)=0, u(+∞)=1, for which we provide existence, non-existence, multiplicity results. The solutions we find can be reviewed as heteroclinic orbits in the (u, u') plane dynamical system

Guiding-like functions for semilinear evolution equations with retarded nonlinearities

The paper deals with a semilinear evolution equation in a reflexive and separable Banach space. The non-linear term is multivalued, upper Caratheodory and it depends on a retarded argument. The existence of global almost exact, i.e. classical, solutions is investigated. The results are based on a continuation principle for condensing multifields and the required transversalities derive from the introduction of suitable generalized guiding functions. As a consequence, the equation has a bounded globally viable set. The results are new also in the lack of retard and in the single valued case. A brief discussion of a non-local diffusion model completes this investigation

On a Nonlocal Boundary Value Problem for Second Order Nonlinear Singular Differential Equations

Criteria for the existence and uniqueness of a solution of a nonlocal second order boundary value problem are estabilished. These criteria apply, in particular, to the case when the nonlinearity has nonintegrable singularities

Heteroclinic orbits in plane dynamical systems

summary:We consider general second order boundary value problems on the whole line of the type $u^{\prime \prime }=h(t,u,u^{\prime })$, $u(-\infty )=0, u(+\infty )=1$, for which we provide existence, non-existence, multiplicity results. The solutions we find can be reviewed as heteroclinic orbits in the $(u,u^{\prime })$ plane dynamical system

Viscous profiles in models of collective movement with negative diffusivity

In this paper, we consider an advection\u2013diffusion equation, in one space dimension, whose diffusivity can be negative. Such equations arise in particular in the modeling of vehicular traffic flows or crowds dynamics, where a negative diffusivity simulates aggregation phenomena. We focus on traveling-wave solutions that connect two states whose diffusivity has different signs; under some geometric conditions, we prove the existence, uniqueness (in a suitable class of solutions avoiding plateaus) and sharpness of the corresponding profiles. Such results are then extended to the case of end states where the diffusivity is positive, but it becomes negative in some interval between them. Also the vanishing viscosity limit is considered. At last, we provide and discuss several examples of diffusivities that change sign and show that our conditions are satisfied for a large class of them in correspondence of real data

Scorza-Dragoni approach to Dirichlet problem in Banach spaces

Hartman-type conditions are presented for the solvability of a multivalued Dirichlet problem in a Banach space by means of topological degree arguments, bounding functions, and a Scorza-Dragoni approximation technique. The required transversality conditions are strictly localized on the boundaries of given bound sets. The main existence and localization result is applied to a partial integro-differential equation involving possible discontinuities in state variables. Two illustrative examples are supplied. The comparison with classical single-valued results in this field is also made