Whenever there is a time delay in a dynamical system, the studyof stability becomes an infinite-dimensional problem. The centre manifold theorem, together with the classical Hopf bifurcation, is the most valuable approach for simplifying theinfinite-dimensional problem without the assumption of small time delay. This dimensional reduction is illustrated in this paper with the delay versions of the Duffing and van der Pol equations. For both nonlinear delay equations, transcendental characteristic equations of linearized stability are examined through Hopf bifurcation. The infinite-dimensional nonlinear solutions of the delay equations are decomposed into stable and centre subspaces, whose respective dimensions are determined by the linearized stability of the transcendental equations. Linear semigroups, infinitesimal generators, and their adjoint forms with bilinear pairings are the additional candidates for the infinite-dimensional reduction.
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机译:每当动力系统存在时间延迟时,对稳定性的研究就成为一个无穷维的问题。中心流形定理与经典的Hopf分支是最简单的方法,它可以简化无穷维问题,而无需假设时间延迟很小。本文使用Duffing和van der Pol方程的延迟版本说明了这种降维。对于这两个非线性延迟方程,通过Hopf分支检验了线性稳定性的先验特性方程。时滞方程的无穷维非线性解被分解成稳定子空间和中心子空间,其子空间的大小由先验方程的线性化稳定性决定。线性半群,无穷小生成器及其带有双线性对的伴随形式是无穷维约简的其他候选对象。
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