Spatio-Temporal Complexity and Large-Scale Structures in Problems of Continuum Mechanics
Final rept. 1 Sep 1989-31 Aug 1992
ARIZONA STATE UNIV TEMPE DEPT OF MATHEMATICS
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We have investigated some difficulties in estimating dynamics from time-delay embeddings of experimental data that can be characterized as low- dimensional. A new procedure is developed to reduce noise by exploiting the properties of saddle periodic orbits on the reconstructed attractor. Most of these methods involve the estimation of a derivative form the data or in some way require a least squares estimate of the location of some portion of the attractor. Our work addresses some of the problems inherent in the estimation-of dynamics from data, regardless of the type of model used to approximate the dynamics. These difficulties may arise from the fractal structure of the attractor and errors in all the-observations. The problems persist regardless of the amount of available data and affect ones ability to determine an accurate local Model of the dynamics, even when an accurate model should be obtainable in principle. Many of these problems can be circumvented by using as much dynamical information as possible In the formulation of the statistical relationship between the observations. Our attempt to do this involves the use of recurrent orbits to derive an accurate linear model of the dynamics in the-vicinity of saddle periodic orbits, on-the attractor. We have applied our method to two experimental data sets from Taylor-Couette flows.
- Fluid Mechanics