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arXiv 1106.1306nlin.CDmath.DSphysics.flu-dyn
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拉格朗日描述子:揭示一般时变动力系统相空间结构的一种方法

Lagrangian Descriptors: A Method for Revealing Phase Space Structures of General Time Dependent Dynamical Systems

Ana M. Mancho, Stephen Wiggins, Jezabel Curbelo, Carolina Mendoza

摘要:

在本文中,我们开发了新的技术,揭示几何结构的相空间是有效的非周期性的时间依赖的动力系统,我们称之为拉格朗日描述符。这些量基于在有限时间内沿着轨迹自身的固有有界、正几何和/或物理性质的轨迹的积分。我们讨论了一个一般的方法来构建拉格朗日描述符,我们讨论了一个“启发式的论点”,解释了为什么这种方法是成功的揭示几何结构的动力系统的相空间。我们支持这一论点明确计算的基准问题有一个双曲不动点与稳定和不稳定的流形,是已知的分析。其他几个基准的例子被认为是让我们评估的性能拉格朗日描述符揭示不变环面和剪切区域。在整个文件“并排”的拉格朗日描述符的性能与有限时间李雅普诺夫指数(FTLES)和有限时间平均的某些组件的向量场(“时间平均值”)进行了比较和讨论。在所有情况下,拉格朗日描述符被证明是更准确和计算效率比这些方法。我们还执行计算明确的三维,非周期性的时间依赖的向量场和非周期性的时间依赖的向量场定义为一个数据集。与FTLE和这些例子的时间平均值的比较也进行了类似的结论,为基准的例子。

英文摘要:

In this paper we develop new techniques for revealing geometrical structures in phase space that are valid for aperiodically time dependent dynamical systems, which we refer to as Lagrangian descriptors. These quantities are based on the integration, for a finite time, along trajectories of an intrinsic bounded, positive geometrical and/or physical property of the trajectory itself. We discuss a general methodology for constructing Lagrangian descriptors, and we discuss a "heuristic argument" that explains why this method is successful for revealing geometrical structures in the phase space of a dynamical system. We support this argument by explicit calculations on a benchmark problem having a hyperbolic fixed point with stable and unstable manifolds that are known analytically. Several other benchmark examples are considered that allow us the assess the performance of Lagrangian descriptors in revealing invariant tori and regions of shear. Throughout the paper "side-by-side" comparisons of the performance of Lagrangian descriptors with both finite time Lyapunov exponents (FTLEs) and finite time averages of certain components of the vector field ("time averages") are carried out and discussed. In all cases Lagrangian descriptors are shown to be both more accurate and computationally efficient than these methods. We also perform computations for an explicitly three dimensional, aperiodically time-dependent vector field and an aperiodically time dependent vector field defined as a data set. Comparisons with FTLEs and time averages for these examples are also carried out, with similar conclusions as for the benchmark examples.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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