Leaf Veins Inspire a New Model for Distribution Networks
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Date posted: 04/03/2010
Posted by: Site Administration
This story is from the category
 Connectivity

A straight line may be the shortest path from A to B, but it's not always the most reliable or efficient way to go. In fact, depending on what's traveling where, the best route may run in circles, according to a new model that bucks decades of theorizing on the subject. A team of biophysicists at Rockefeller University developed a mathematical model showing that complex sets of interconnecting loops - like the netted veins that transport water in a leaf -- provide the best distribution network for supplying fluctuating loads to varying parts of the system. It also shows that such a network can best handle damage.

The findings could change the way engineers think about designing networks to handle a variety of challenges like the distribution of water or electricity in a city.

Operations researchers have long believed that the best distribution networks for many scenarios look like trees, with a succession of branches stemming from a central stalk and then branches from those branches and so on, to the desired destinations. But this kind of network is vulnerable: If it is severed at any place, the network is cut in two and cargo will fail to reach any point "downstream" of the break.

By contrast, in the leaves of most complex plants, evolution has devised a system to distribute water that is more supple in at least two key ways. Plants are under constant attack from bugs, diseases, animals and the weather. If a leaf's distribution network were tree-like and damaged, the part of the leaf downstream of the damage would starve for water and die. In some of the Earth's more ancient plants, such as the gingko, this is the case. But many younger, more sophisticated plants have evolved a vein system of interconnected loops that can reroute water around any damage, providing many paths to any given point, as in the lemon leaf. Operations researchers have appreciated that these redundancies are an effective hedge against damage. What's most surprising in the new research, according to

Marcelo O. Magnasco, head of the Laboratory of Mathematical Physics at Rockefeller University, is that the complex network also does a better job of handling fluctuating loads according to shifts in demand from different parts of the system - a common real-world need within dynamic distribution networks.

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