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arXiv 2005.06084math.DSmath.CAmath.FA
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常微分方程状态相关延迟扰动的参数化方法

Parameterization method for state-dependent delay perturbation of an ordinary differential equation

Jiaqi Yang, Joan Gimeno, Rafael de la Llave

摘要:

本文考虑了一个具有极限环的平面常微分方程的状态依赖时滞方程。这些情况出现在几个物理过程的模型中,其中添加了小的延迟效应。即使延迟很小,它们也是非常奇异扰动,因为SDDE的自然相空间是无限维空间。我们发现,SDDE承认的解决方案,类似的解决方案的常微分方程。也就是说,存在一个周期解和一个双参数解族,其演化收敛于周期解。即使SDDE的相空间自然是一个空间的功能,我们表明,有初始值,导致类似的ODE的解决方案。证明方法绕过了SDDE的存在性、唯一性、参数依赖性等理论。我们认为,有一个很好的定义的行为(如周期性的,或渐近周期性)的时间函数的类,并推导出一个函数方程,它规定,他们是SDDE的解决方案。这些函数方程研究使用的泛函分析的方法。我们给出了一个“后验”形式的结果:给定函数方程的一个近似解,如果它具有好的条件数,我们证明了存在接近近似解的真解.因此,我们可以用这个结果来验证数值计算的结果。证明的方法也导致实际的算法。在配套文件中,我们提出的实施细节和代表性的结果。这里提出的方法的一个特点是,它允许获得光滑的依赖于参数的周期性的解决方案和他们的慢稳定的流形,而不研究的光滑性的流动(这似乎是有问题的SDDE,现在的最佳结果光滑的流动是$C^1$)。

英文摘要:

We consider state-dependent delay equations (SDDE) obtained by adding delays to a planar ordinary differential equation with a limit cycle. These situations appear in models of several physical processes, where small delay effects are added. Even if the delays are small, they are very singular perturbations since the natural phase space of an SDDE is an infinite dimensional space. We show that the SDDE admits solutions which resemble the solutions of the ODE. That is, there exist a periodic solution and a two parameter family of solutions whose evolution converges to the periodic solution. Even if the phase space of the SDDE is naturally a space of functions, we show that there are initial values which lead to solutions similar to that of the ODE. The method of proof bypasses the theory of existence, uniqueness, dependence on parameters of SDDE. We consider the class of functions of time that have a well defined behavior (e.g. periodic, or asymptotic to periodic) and derive a functional equation which imposes that they are solutions of the SDDE. These functional equations are studied using methods of functional analysis. We provide a result in "a posteriori" format: Given an approximate solution of the functional equation, which has some good condition numbers, we prove that there is true solution close to the approximate one. Thus, we can use the result to validate the results of numerical computations. The method of proof leads also to practical algorithms. In a companion paper, we present the implementation details and representative results. One feature of the method presented here is that it allows to obtain smooth dependence on parameters for the periodic solutions and their slow stable manifolds without studying the smoothness of the flow (which seems to be problematic for SDDEs, for now the optimal result on smoothness of the flow is $C^1$).

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