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A technique able to significantly reduce the energy consumption of contention-based MAC protocols for wireless sensor networks is presented. Address and timing information is embedded into the packet preamble, allowing receivers to power off their radio during part of the transmission. Analytical and experimental evaluations show a significant extension of the network lifetime.

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This paper analyses the performance of a genetic algorithm (GA) in the synthesis of digital circuits using two novel approaches. The first concept consists in improving the static fitness function by including a discontinuity Evaluation. The measure of variability in the error of the Boolean table has similarities with the function continuity issue in classical calculus. The second concept extends the static fitness by introducing a fractional-order dynamical. evaluation. The dynamic-fitness function results from an analogy with control systems where it is possible to benefit the proportional algorithm by including a differential scheme. It is investigated the CA performance when adopting each concept separately. The experiments reveal superior results, in terms of speed and convergence of the number of iterations required to achieve a, solution. In a final phase the two concepts are integrated in the GA fitness function leading to the best performance.

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The IP Multimedia Subsystem (IMS), standardized by 3GPP, can be seen as a way of offering Internet services, such as the Web access, electronic mail or instant messaging, through any access technology, in terms of terminals and networks. This paper presents a proposal to solve the problem of the dynamic adaptation of multimedia services provided in the Web context. The proposed solution is based on the real-time generation of user interfaces conditioned by the user context. The solution is mainly characterized by the approach used for resolving the existing dependencies among user interface variables and by the mechanism for acquiring the user context information, which uses the Parlay middleware.

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In this work. the LPG-assisted fibre Michelson modal interferometer is studied as a sensing structure to environmental refractive index, temperature and liquid level when coherence addressing and heterodyne interrogation are considered. The effects on measurand sensitivity of the order of the cladding mode excited by the LPG, of the degree c etching of the sensing fibre and of the fibre type used are investigated.

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