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Monotonicity of the period function for some planar differential systems. Part I: Conservative and quadratic systems

A. Raouf Chouikha (2005)

Applicationes Mathematicae

We first examine conditions implying monotonicity of the period function for potential systems with a center at 0 (in the whole period annulus). We also present a short comparative survey of the different criteria. We apply these results to quadratic Loud systems ( L D , F ) for various values of the parameters D and F. In the case of noncritical periods we propose an algorithm to test the monotonicity of the period function for ( L D , F ) . Our results may be viewed as a contribution to proving (or disproving) a conjecture...

Monotonicity of the period function for some planar differential systems. Part II: Liénard and related systems

A. Raouf Chouikha (2005)

Applicationes Mathematicae

We are interested in conditions under which the two-dimensional autonomous system ẋ = y, ẏ = -g(x) - f(x)y, has a local center with monotonic period function. When f and g are (non-odd) analytic functions, Christopher and Devlin [C-D] gave a simple necessary and sufficient condition for the period to be constant. We propose a simple proof of their result. Moreover, in the case when f and g are of class C³, the Liénard systems can have a monotonic period function...

Monotonicity properties of oscillatory solutions of differential equation ( a ( t ) | y ' | p - 1 y ' ) ' + f ( t , y , y ' ) = 0

Miroslav Bartušek, Chrysi G. Kokologiannaki (2013)

Archivum Mathematicum

We obtain monotonicity results concerning the oscillatory solutions of the differential equation ( a ( t ) | y ' | p - 1 y ' ) ' + f ( t , y , y ' ) = 0 . The obtained results generalize the results given by the first author in [1] (1976). We also give some results concerning a special case of the above differential equation.

Motion of spirals by crystalline curvature

Hitoshi Imai, Naoyuki Ishimura, TaKeo Ushijima (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

Modern physics theories claim that the dynamics of interfaces between the two-phase is described by the evolution equations involving the curvature and various kinematic energies. We consider the motion of spiral-shaped polygonal curves by its crystalline curvature, which deserves a mathematical model of real crystals. Exploiting the comparison principle, we show the local existence and uniqueness of the solution.

Multi-dimensional Cartan prolongation and special k-flags

Piotr Mormul (2004)

Banach Center Publications

Since the mid-nineties it has gradually become understood that the Cartan prolongation of rank 2 distributions is a key operation leading locally, when applied many times, to all so-called Goursat distributions. That is those, whose derived flag of consecutive Lie squares is a 1-flag (growing in ranks always by 1). We first observe that successive generalized Cartan prolongations (gCp) of rank k + 1 distributions lead locally to all special k-flags: rank k + 1 distributions D with the derived...

Multiple periodic solutions for Hamiltonian systems with singular potential

Addolorata Salvatore (1992)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

In this Note we prove the existence of infinitely many periodic solutions of prescribed period for a Hamiltonian system with a singular potential.

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