Brake Orbits of First Order Convex Hamiltonian Systems with Particular Anisotropic Growth

Combining the dual least action principle with Mountain-pass lemma,we obtain the existence of brake orbits for first-order convex Hamiltonian systems with particular anisotropic growth.     

The study of minimal period estimates for brake orbits of autonomous subquadratic Hamiltonian systems

In this paper, we consider the minimal period estimates for brake orbits of autonomous subquadratic Hamiltonian systems. We prove that if the Hamiltonian function H ∈ C2(R2n, R) is unbounded and not uniformly coercive, there exists at least one nonconstant T-periodic brake orbit(z, T) with minimal period T or T /2 for every number T 0.     

Multiple brake orbits of even Hamiltonian systems on torus

In this paper,we establish a relationship between the Morse index at rest points in the saddle point reduction and the brake-orbit-type Maslov index at corresponding brake orbits.As an application,we give a criterion to find brake orbits which are contractible and start at {0}×T~n■T~(2 n) for even Hamiltonian on T~(2 n) by the methods of the Maslov-index theory and a critical point theorem formulated by Bartsch and Wang(1997).Explicitly,if all trivial solutions of a Hamiltonian are nondegenerate in the brake orbit boundary case,there are at least max{i_(L_0)(z_0)} pairs of nontrivial 1-periodic brake orbits if i_(L_0)(z_0) 0 or at least max{-i_(L_0)(z_0)-n}pairs of nontrivial 1-periodic brake orbits if i_(L_0)(z_0) -n.In the end,we give an example to find brake orbits for certain Hamiltonian via this criterion.     

一类Hamilton系统的同宿解存在性

We study the existence of homoclinic orbits for some Hamiltonian system.A homoclinic orbit is obtained as a limit of 2kT-periodic solutions of a sequence of systems of differential equations.     

HOMOCLINIC ORBITS FOR A CLASS OF HAMILTONIAN SYSTEMS WITH POTENTIALS CHANGING SIGN

In this paper, we prove the existence of nontrivial homoclinic orbits for a class of Hamiltonian systems with potential changing sign. We use Mountain Pass Lemma.     

具有小受迫项的哈密顿系统的同宿轨道

By Brezis-Nirenberg type Mountain Pass Theorem, the research has focused on the existence of nontrivial homoclinic orbits for a class of second order Hamiltonian systems with non-Ambrosetti-Rabinowitz type superquadratic potentials and small forced terms.     

Shadowing Homoclinic Chains to a Symplectic Critical Manifold

We prove the existence of trajectories shadowing chains of heteroclinic orbits to a symplectic normally hyperbolic critical manifold of a Hamiltonian system.The results are quite different for real and complex eigenvalues. General results are applied to Hamiltonian systems depending on a parameter which slowly changes with rate ε. If the frozen autonomous system has a hyperbolic equilibrium possessing transverse homoclinic orbits, we construct trajectories shadowing homoclinic chains with energy having quasirandom jumps of order ε and changing with average rate of orderε| ln ε|. This provides a partial multidimensional extension of the results of A. Neishtadt on the destruction of adiabatic invariants for systems with one degree of freedom and a figure 8 separatrix.     

NEW FAMILIES OF CENTERS AND LIMIT CYCLES FOR POLYNOMIAL DIFFERENTIAL SYSTEMS WITH HOMOGENEOUS NONLINEARITIES

We consider the class of polynomial differential equations x = -y+Pn(x,y), y = x + Qn(x, y), where Pn and Qn are homogeneous polynomials of degree n. Inside this class we identify a new subclass of systems having a center at the origin. We show that this subclass contains at least two subfamilies of isochro-nous centers. By using a method different from the classical ones, we study the limit cycles that bifurcate from the periodic orbits of such centers when we perturb them inside the class of all polynomial differential systems of the above form. In particular, we present a function whose simple zeros correspond to the limit cycles vvhich bifurcate from the periodic orbits of Hamiltonian systems.     

Brake Orbits of a Reversible Even Hamiltonian System Near an Equilibrium

In this paper,we consider the brake orbits of a reversible even Hamiltonian system near an equilibrium.Let the Hamiltonian system(H S)x=J H(x)satisfies H(0)=0,H(0)=0,reversible and even conditions H(Nx)=H(x)and H(-x)=H(x)for all x∈R²ⁿ.Suppose the quadratic form Q(x)=1/2 is non-degenerate.Fixτ₀>0 and assume that R²ⁿ=E⊕F decomposes into linear subspaces E and F which are invariant under the flow associated to the linear system x=J H'(0)x and such that each solution of the above linear system in E isτ₀-periodic whereas no solution in F{0}isτ₀-periodic.Writeσ(τ₀)=σ_Q(τ₀)for the signature of Q|E.Ifσ(τ₀)≠=0,we prove that either there exists a sequence of brake orbits x_k→0 withτk-periodic on the hypersurface H^-1(0)whereτ_k→τ₀;or for eachλclose to 0 withλ_σ(τ₀)>0 the hypersurface H-1(λ)contains at least 1/2|σ(τ₀)|distinct brake orbits of the Hamiltonian system(HS)near 0 with periods nearτ₀.Such result for periodic solutions was proved by Bartsch in 1997.     

Mean Index for Non-periodic Orbits in Hamiltonian Systems

In this paper,we define mean index for non-periodic orbits in Hamiltonian systems and study its properties.In general,the mean index is an interval in R which is uniformly continuous on the systems.We show that the index interval is a point for a quasi-periodic orbit.The mean index can be considered as a generalization of rotation number defined by Johnson and Moser in the study of almost periodic Schr¨odinger operators.Motivated by their works,we study the relation of Fredholm property of the linear operator and the mean index at the end of the paper.     

Galerkin’s method, monotonicity and linking for indefinite Hamiltonian systems with bounded potential energy

A combination of Galerkins method and linking theory with monotonicity in the calculus of variations is used to study Hamiltonian systems in which the kinetic-energy functional is a (not necessarily definite) quadratic form and the potential-energy functional may be bounded. The existence of non-constant brake periodic orbits for almost all prescribed energies is established. An example of a Hamiltonian system which satisfies our hypotheses but has no non-constant brake periodic orbits with energy in an uncountable set of measure zero is given. Additional hypotheses, sufficient to ensure the existence of non-constant brake periodic orbits of all energies, are found.Received: 28 November 2003, Accepted: 2 June 2004, Published online: 3 September 2004Mathematics Subject Classification (2000): 37J45     

Examples with minimal number of brake orbits and homoclinics in annular potential regions

We use a geometric construction to exhibit examples of autonomous Lagrangian systems admitting exactly two homoclinics emanating from a nondegenerate maximum of the potential energy and reaching a regular level of the potential having the same value of the maximum point. Similarly, we show examples of Hamiltonian systems that admit exactly two brake orbits in an annular potential region connecting the two connected components of the boundary of the potential well. These examples show that the estimates proven in [2] are sharp.     

Homoclinic Orbits for a Class of Fractional Hamiltonian Systems via Variational Methods

This paper is devoted to the existence and multiplicity of homoclinic orbits for a class of fractional-order Hamiltonian systems with left and right Liouville–Weyl fractional derivatives. Here, we present a new approach via variational methods and critical point theory to obtain sufficient conditions under which the Hamiltonian system has at least one homoclinic orbit or multiple homoclinic orbits. Some results are new even for second-order Hamiltonian systems.     

Long periodic orbits near an equilibrium and the averaging method in higher-order resonances

We consider the bifurcation of periodic orbits from an equilibrium in Hamiltonian systems. The averaging method is developed in higher-order resonance cases. For systems with general degrees of freedom, the conditions for the existence of long periodic orbits can be written in a simple form in terms of the coefficients of higher-order terms of the normalized Hamiltonian function.     

Maslov index for homoclinic orbits of Hamiltonian systems

A useful tool for studying nonlinear differential equations is index theory. For symplectic paths on bounded intervals, the index theory has been completely established, which revealed tremendous applications in the study of periodic orbits of Hamiltonian systems. Nevertheless, analogous questions concerning homoclinic orbits are still left open. In this paper we use a geometric approach to set up Maslov index for homoclinic orbits of Hamiltonian systems. On the other hand, a relative Morse index for homoclinic orbits will be derived through Fredholm index theory. It will be shown that these two indices coincide.     

On averaging,reduction, and symmetry in hamiltonian systems

The existence of periodic orbits for Hamiltonian systems at low positive energies can be deduced from the existence of nondegenerate critical points of an averaged Hamiltonian on an associated “reduced space.” Alternatively, in classical (kinetic plus potential energy) Hamiltonians the existence of such orbits can often be established by elementary geometrical arguments. The present paper unifies the two approaches by exploiting discrete symmetries, including reversing diffeomorphisms, that occur in a given system. The symmetries are used to locate the periodic orbits in the averaged Hamiltonian, and thence in the original Hamiltonian when the periodic orbits are continued under perturbations admitting the same symmetries. In applications to the Hénon-Heiles Hamiltonian, it is illustrated how “higher order” averaging can sometimes be used to overcome degeneracies encountered at first order.     

Homoclinic orbits for a class of first-order nonperiodic asymptotically quadratic Hamiltonian systems with spectrum point zero

In this paper, we study the existence and multiplicity of homoclinic orbits for a class of first-order nonperiodic Hamiltonian systems. By applying two recent critical point theorems for strongly indefinite functionals, we give some new criteria to guarantee that Hamiltonian systems with asymptotically quadratic terms and spectrum point zero have at least one and a finite number of pairs of homoclinic orbits under some adequate conditions, respectively.