Europhys. Lett.
Volume 67, Number 5, September 2004
Page(s) 734 - 740
Section General
Published online 01 August 2004
Europhys. Lett., 67 (5), pp. 734-740 (2004)
DOI: 10.1209/epl/i2004-10114-9

Optimal random searches of revisitable targets: Crossover from superdiffusive to ballistic random walks

M. C. Santos1, E. P. Raposo2, G. M. Viswanathan3 and M. G. E. da Luz1

1  Departamento de Física, Universidade Federal do Paraná 81531-990, Curitiba-PR, Brazil
2  Laboratório de Física Teórica e Computacional, Departamento de Física Universidade Federal de Pernambuco - 50670-901, Recife-PE, Brazil
3  Departamento de Física, Universidade Federal de Alagoas 57072-970, Maceió-AL, Brazil

(Received 2 April 2004; accepted in final form 16 June 2004)

One of the most important aspects in the general search problem of finding randomly located target sites concerns how to characterize the role played by the non-revisitability delay time $\tau$ during which a previously found target becomes unavailable to the searcher. By using an appropriate parameterization of the number of random walk steps undertaken between successive targets, we show that for the case of sparse randomly distributed sites the optimal search strategy shifts from a superdiffusive to a ballistic strategy consisting of essentially rectilinear motion between the targets, as $\tau$ increases from $\tau\rightarrow 0$ to $\tau\rightarrow\infty$, respectively. The crossover between these limiting regimes occurs as a function of $\tau$. These conclusions are shown to hold even if dissipative phenomena are considered in the searching dynamics. We discuss the results in the context of their application to animal foraging.

05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.

© EDP Sciences 2004