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Five limit cycles for a simple cubic system.

Noel G. Lloyd, Jane M. Pearson (1997)

Publicacions Matemàtiques

We resolve the centre-focus problem for a specific class of cubic systems and determine the number of limit cycles which can bifurcate from a fine focus. We also describe the methods which we have developed to investigate these questions in general. These involve extensive use of Computer Algebra; we have chosen to use REDUCE.

Fixed point analysis for non-oscillatory solutions of quasi linear ordinary differential equations

Luisa Malaguti, Valentina Taddei (2005)

Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica

The paper deals with the quasi-linear ordinary differential equation ( r ( t ) ϕ ( u ' ) ) ' + g ( t , u ) = 0 with t [ 0 , ) . We treat the case when g is not necessarily monotone in its second argument and assume usual conditions on r ( t ) and ϕ ( u ) . We find necessary and sufficient conditions for the existence of unbounded non-oscillatory solutions. By means of a fixed point technique we investigate their growth, proving the coexistence of solutions with different asymptotic behaviors. The results generalize previous ones due to Elbert–Kusano, [Acta...

Flatness and Monge parameterization of two-input systems, control-affine with 4 states or general with 3 states

David Avanessoff, Jean-Baptiste Pomet (2007)

ESAIM: Control, Optimisation and Calculus of Variations

This paper studies Monge parameterization, or differential flatness, of control-affine systems with four states and two controls. Some of them are known to be flat, and this implies admitting a Monge parameterization. Focusing on systems outside this class, we describe the only possible structure of such a parameterization for these systems, and give a lower bound on the order of this parameterization, if it exists. This lower-bound is good enough to recover the known results about “(x,u)-flatness”...

Forced oscillation of third order nonlinear dynamic equations on time scales

Baoguo Jia (2010)

Annales Polonici Mathematici

Consider the third order nonlinear dynamic equation x Δ Δ Δ ( t ) + p ( t ) f ( x ) = g ( t ) , (*) on a time scale which is unbounded above. The function f ∈ C(,) is assumed to satisfy xf(x) > 0 for x ≠ 0 and be nondecreasing. We study the oscillatory behaviour of solutions of (*). As an application, we find that the nonlinear difference equation Δ ³ x ( n ) + n α | x | γ s g n ( n ) = ( - 1 ) n c , where α ≥ -1, γ > 0, c > 3, is oscillatory.

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