Maintaining chaos in physical and biological systems
Mark L. Spano 
, William L. Ditto 
and Visarath In
US Naval Surface Warfare Center, White Oak Laboratory,
Silver Spring,
Maryland, USA 20903;
Georgia Institute of Technology, School of Physics, Atlanta, Georgia, USA 30332
Although for many complex systems the appearance of chaotic behavior may be something to be avoided and perhaps to be controlled, chaos may actually be desirable in, and may enhance the function of, other systems. Possible examples are the functioning of the brain and the mixing of fluids. We have developed a general methodology for maintaining chaos in such systems. The method is based on the return map of the experimental data and requires only small, very infrequently applied perturbations of a single system parameter. It does not require any model equations for, or a priori knowledge of, the system dynamics. This "anticontrol" of chaos has been successfully implemented in a simple experiment based on a magnetoelastic ribbon.