Using networks locally to make a global impact

Rice’s Dueñas-Osorio part of research group exploring networks on a broad scale

BY PATRICK KURP
Special to Rice News

Leonardo Dueñas-Osorio is the lone civil engineer in a research network made up of physicists, anthropologists, computer scientists and control theorists, among other disciplines.

Leonardo Dueñas-Osorio

“What we all have in common is a single interest — networks — and how they work and what happens when they don’t work,” said Dueñas-Osorio, an associate professor of civil and environmental engineering at Rice whose research has often focused on power grid failure, urban water security and the chances of homes in Houston being damaged by high winds or flooding during a hurricane. “One of the things we want to know is how to push a network in the right direction and with just enough force to get it working again.”

His 15-member research group’s initial finding, “Exotic states in a simple network of nanoelectromechanical oscillators,” was published March 8 in the journal Science. The subject is networks in the broadest sense, from nano- to macro-scale. Dueñas-Osorio usually works at the macro end of things.

The research suggests that even a simple network of synchronized nanomachines can result in complex, out-of-sync states. Perfect synchronization of nodes can be beneficial, as in power grids or communication networks, but can also be dangerous, as when neurons fire in unison and cause an epileptic seizure.

Dueñas-Osorio worked with researchers at the California Institute of Technology (Caltech) who devised a network using nanoelectromechanical system (NEMS) oscillators with minute membranes that vibrate in response to an input frequency. They arranged eight NEMS oscillators in a ring, with each connected to two adjoining oscillators, thus forming a small, experimentally useful network.

Their eight-node ring network spontaneously resulted in various “exotic” and complicated states. In some cases, nodes synchronized with neighboring nodes; in others, nodes on opposite sides of the network, without a direct connection, synchronized.

“This hasn’t been experimentally demonstrated before,” Dueñas-Osorio said. “It’s as though the network is greater than the sum of its parts. This suggests that we can do something locally that will have an impact globally.”

The researchers’ next step is to assemble progressively larger, more complex networks of nodes. By coming to understand how they function “below the surface,” they hope eventually to control their behavior. Some in the group have even applied network dynamics theory to the social networks of macaque monkeys at the California National Primate Research Center.

“The human implications are enormous,” Dueñas-Osorio said. “How can we keep our various networks safe? What about our social and economic networks? Humans interact significantly with technological networks, too, hence the need for understanding joint systems.”

The project is funded primarily by a five-year, $6.7 million Multidisciplinary University Research Initiative grant from the Army Research Office. Rice’s academic partners are the University of California, Davis (lead partner); the University of Washington and Caltech.

–Patrick Kurp is a science writer in the George R. Brown School of Engineering.