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arXiv 0807.0678nlin.CD
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二次保体积映射:不变圆与分歧

Quadratic Volume-Preserving Maps: Invariant Circles and Bifurcations

Holger R. Dullin, James D. Meiss

摘要:

我们研究了R^3的五参数二次保体积同态族的动力学。这个族是具有31乘子的不动点分支的展开正规形,也是具有二次逆的二次三维映射的一般形式。当它的两个不动点是鞍焦点时,这个映射的许多非平凡动力学就发生了,鞍焦点具有相交的二维稳定和不稳定流形,这些流形约束了一个球形的“涡泡”。我们发现,这发生在鞍中心Neimark-Sacker(SCNS)分叉,也创建,至少在其正常形式,椭圆不变圆附近。我们开发了一个简单的算法来精确地计算这些椭圆不变圆和它们的纵向和横向旋转数,并用它来研究它们的分叉,通过旋转数之间的共振将它们分类。特别是,合理的值的纵向旋转数所示,以产生一串珍珠,创建多个副本的原始球形结构的一个副本的地图。

英文摘要:

We study the dynamics of the five-parameter quadratic family of volume-preserving diffeomorphisms of R^3. This family is the unfolded normal form for a bifurcation of a fixed point with a triple-one multiplier and also is the general form of a quadratic three-dimensional map with a quadratic inverse. Much of the nontrivial dynamics of this map occurs when its two fixed points are saddle-foci with intersecting two-dimensional stable and unstable manifolds that bound a spherical ``vortex-bubble''. We show that this occurs near a saddle-center-Neimark-Sacker (SCNS) bifurcation that also creates, at least in its normal form, an elliptic invariant circle. We develop a simple algorithm to accurately compute these elliptic invariant circles and their longitudinal and transverse rotation numbers and use it to study their bifurcations, classifying them by the resonances between the rotation numbers. In particular, rational values of the longitudinal rotation number are shown to give rise to a string of pearls that creates multiple copies of the original spherical structure for an iterate of the map.

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