No abstract

International audienceLarge applications of sensor networks, such as environmental risk monitoring, require the deployment of hundreds or even thousands of nodes. This study proposes and implements a novel stochastic physics-based optimisation algorithm that is both efficient (guarantees full target coverage with a reduced number of sensors) and scalable (meaning that it can be executed for very large-scale problems in a reasonable computation time). The algorithm employs ‘virtual sensors’ which move, merge, recombine, and ‘explode’ during the course of the algorithm, where the process of merging and recombining virtual sensors reduces the number of actual sensors while maintaining full coverage. The parameters which control sensor merging and explosion are varied during the algorithm to perform the same function as an annealing schedule in simulated annealing. Simulation results illustrate the rapidity and the effectiveness of the proposed method

No abstract

A new method is proposed in this paper to detect oil slick signatures in oceanographic SAR images. This method is based on directional behavioural oil slick in the sea surface. Therefore, directional hysteresis thresholding responses are first computed in order to bring to the fore dark spots, and increase pixels connexity in each Freeman direction. Those responses are then merged with the help of a Context Independent Constant Behaviour (CICB) operator. The proposed method is tested on ERS SAR amplitude images of Mediterranean and Atlantic seas. The obtained results are promising and show a good qualitative detection. 0-7803-7929-2/03/$17.00 (C) 2003 IEEE

Bandwidth enhancement of the traditional inset‐fed rectangular microstrip patch antenna is numerically analyzed using degraded ground plane technique. Input impedance calculation based on the electromagnetic theory in traveling‐wave in conjunction with field distribution in quasi‐TEM mode approximation is carried out. Radiated electric field properties are performed using Ampere's law of the magneto‐static. Some antenna performances such as −10 dB return loss bandwidth of 36.7%, beam‐width of about 94°, and stable gain of 3.4 dB have been achieved.