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B R Hunt

Publications and source records attributed to B R Hunt.

5 recordsLinked to original sources
PubMed2001

Fractal properties of robust strange nonchaotic attractors.

For a simple class of quasiperiodically forced dynamical systems, we present a rigorous result supporting the idea that the attractors for this class of systems, although nonchaotic, are strange in the sense that their box-counting dimension is two while their information dimension is one. Furthermore, this result is stable to changes of the system, suggesting that the basic features leading to it may be present in typical quasiperiodically forced systems.

Journal Article↗
PubMed2001

Local low dimensionality of atmospheric dynamics.

A statistic, the BV (bred vector) dimension, is introduced to measure the effective local finite-time dimensionality of a spatiotemporally chaotic system. It is shown that the Earth's atmosphere often has low BV dimension, and the implications for improving weather forecasting are discussed.

Journal Article↗
PubMed2000

Image restoration with the Viterbi algorithm.

The Viterbi algorithm (VA) is known to given an optimal solution to the problem of estimating one-dimensional sequences of discrete-valued pixels corrupted by finite-support blur and memoryless noise. A row-by-row estimation along with decision feedback and vector quantization is used to reduce the computational complexity of the VA and allow the estimation of two-dimensional images. This reduced-complexity VA (RCVA) is shown to produce near-optimal estimation of random binary images. In addition, simulated restorations of gray-scale images show the RCVA estimates to be an improvement over the estimates obtained by the conventional Wiener filter (WF). Unlike the WF, the RCVA is capable of superresolution and is adaptable for use in restoring data from signal-dependent Poisson noise corruption. Experimental restorations of random binary data gathered from an optical imaging system support the simulations and show that the RCVA estimate has fewer than one third of the errors of the WF estimate.

Algorithms↗
PubMed1999

Box-counting dimension without boxes: computing D0 from average expansion rates.

We propose an efficient iterative scheme for calculating the box-counting (capacity) dimension of a chaotic attractor in terms of its average expansion rates. Similar to the Kaplan-Yorke conjecture for the information dimension, this scheme provides a connection between a geometric property of a strange set and its underlying dynamical properties. Our conjecture is demonstrated analytically with an exactly solvable two-dimensional hyperbolic map, and numerically with a more complicated higher-dimensional nonhyperbolic map.

Biophysical Phenomena↗