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发帖数: 3461 | 1 http://www.ncbi.nlm.nih.gov/pubmed/22401258
Phys Rev Lett. 2012 Feb 17;108(7):078101. Epub 2012 Feb 13.
Shape of a ponytail and the statistical physics of hair fiber bundles.
Goldstein RE, Warren PB, Ball RC.
Source
Department of Applied Mathematics and Theoretical Physics, University of
Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom.
Abstract
A general continuum theory for the distribution of hairs in a bundle is
developed, treating individual fibers as elastic filaments with random
intrinsic curvatures. Applying this formalism to the iconic problem of the
ponytail, the combined effects of bending elasticity, gravity, and
orientational disorder are recast as a differential equation for the
envelope of the bundle, in which the compressibility enters through an "
equation of state." From this, we identify the balance of forces in various
regions of the ponytail, extract a remarkably simple equation of state from
laboratory measurements of human ponytails, and relate the pressure to the
measured random curvatures of individual hairs. |
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