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A common task for robots is the patrolling of an unknown area with inadequate information about target locations. Under these circumstances it has been suggested that animal foraging could provide an optimal or at least suboptimal search methodology, namely the Levy flight search. Although still in debate, it seems that predators somehow follow this search pattern when foraging, because it avoids being trapped in a local search if the food is beyond the sensory range. A Levy flight is a particular case of the random walk. Its displacements on a 2-D surface are drawn from the Pareto-Levy probability distribution, characterized by power law tails. The Levy flight search has many applications in optical material, ladars, optics, large database search, earthquake data analysis, location of DNA sites, human mobility, stock return analysis, online auctions, astronomy, ecology and biology. Almost all studies and simulations concerning the Levy flight foraging examine static or slowly moving (with respect to the forager) uniformly distributed resources. Moreover, in recent works a small swarm of underwater autonomous vehicles has been used to test the standard Levy search in the underwater environment, with good results. In this paper we extend the classical Levy foraging framework taking into consideration a moving target allocated on a 2-D surface according to a radial probability distribution and comparing its performance with the random walk search. The metric used in the numerical simulations is the detection rate. Simulations include the sensor resolution, intended as the maximum detection distance of the forager from the target. Furthermore, contrarily to the usual Levy foraging framework, we use only one target. Results show that Levy flight outperforms the random walk if the sensor detection radius is not too small or too large. We also find the Levy flight in the velocity of the center of mass model of a fish school according the Kuramoto equation, a famous model of synchronization phenomena. Finally, a discussion about the controversy concerning the innate or evolutionary origin of the Levy foraging is given.

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The increasing interest in the application of optical communications to underwater communications and networks calls for reliable simulation models, that allow a system designer to realistically assess the performance of optical systems before actual deployment in water. In this paper, we present an optical channel model that is based on samples of the total attenuation coefficient and of solar light irradiance taken during the NATO STO CMRE ALOMEX'15 scientific cruise, in different water conditions. The data set includes both strong and mild solar illumination conditions, as well as a number of different settings for the light absorption and scattering coefficients.We implement the model as part of the DESERT Underwater network simulator, and employ it to show that the throughput of underwater optical links depends not only on the distance between the transmitter and the receiver, but also on the depth at which the devices are deployed. The corresponding insight is empirically validated in dry tests and lake experiments using a proof-of-concept optical modem, and helped drive the next stage of the modem development.