3,018 research outputs found

    Inventaire bibliographique des algues benthiques du littoral marocain. I. Chlorophyceae et Phaeophyceae

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    nventaire préliminaire des algues benthiques du littoral marocain. I. Chlorophyceae et Phaeophyceae. L'inventaire bibliographique des Chlorophyceae et Phaeophyceae marines benthiques du littoral marocain a révélé 213 espèces dont 93 Chlorophyceae (6 ordres, 15 familles et 31 genres) et 110 Phaeophyceae (11 ordres, 20 familles et 50 genres

    Feedback control logic synthesis for non safe Petri nets

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    This paper addresses the problem of forbidden states of non safe Petri Net (PN) modelling discrete events systems. To prevent the forbidden states, it is possible to use conditions or predicates associated with transitions. Generally, there are many forbidden states, thus many complex conditions are associated with the transitions. A new idea for computing predicates in non safe Petri nets will be presented. Using this method, we can construct a maximally permissive controller if it exists

    Controller synthesis with very simplified linear constraints in PN model

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    This paper addresses the problem of forbidden states for safe Petri net modeling discrete event systems. We present an efficient method to construct a controller. A set of linear constraints allow forbidding the reachability of specific states. The number of these so-called forbidden states and consequently the number of constraints are large and lead to a large number of control places. A systematic method for constructing very simplified controller is offered. By using a method based on Petri nets partial invariants, maximal permissive controllers are determined.Comment: Dependable Control of discrete Systems, Bari : Italie (2009

    On short-term traffic flow forecasting and its reliability

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    Recent advances in time series, where deterministic and stochastic modelings as well as the storage and analysis of big data are useless, permit a new approach to short-term traffic flow forecasting and to its reliability, i.e., to the traffic volatility. Several convincing computer simulations, which utilize concrete data, are presented and discussed.Comment: 8th IFAC Conference on Manufacturing Modeling, Management & Control (Troyes, France, June 2016

    Handover Necessity Estimation for 4G Heterogeneous Networks

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    One of the most challenges of 4G network is to have a unified network of heterogeneous wireless networks. To achieve seamless mobility in such a diverse environment, vertical hand off is still a challenging problem. In many situations handover failures and unnecessary handoffs are triggered causing degradation of services, reduction in throughput and increase the blocking probability and packet loss. In this paper a new vertical handoff decision algorithm handover necessity estimation (HNE), is proposed to minimize the number of handover failure and unnecessary handover in heterogeneous wireless networks. we have proposed a multi criteria vertical handoff decision algorithm based on two parts: traveling time estimation and time threshold calculation. Our proposed methods are compared against two other methods: (a) the fixed RSS threshold based method, in which handovers between the cellular network and the WLAN are initiated when the RSS from the WLAN reaches a fixed threshold, and (b) the hysteresis based method, in which a hysteresis is introduced to prevent the ping-pong effect. Simulation results show that, this method reduced the number of handover failures and unnecessary handovers up to 80% and 70%, respectively

    Adsorption of uranium and thorium on new adsorbent prepared from Moroccan oil shale impregnated with phosphoric acid

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    Attention has been focused recently on the production of new adsorbents from Moroccan oil shale of Tarfaya (layer R3) by chemical activation with phosphoric acid and its application in wastewaters treatment. The optimal conditions for the preparation were searched and the tests of adsorption of uranium and thorium ions were affected. The best product was obtained by used of the ratio of activated agent/precursor equal 3 and activation of the mixture in air at 250°C during two hours after prepocessing at 120°C in air. Under these conditions the maximal adsorption capacity of methylene blue and specific area (SBET) of the new adsorbent were 526 mg/g and 630 m2/g, respectively. A batch mode experiment was used to explore the performances of this adsorbent for the removal of the U and Th from aqueous solutions prepared from UO2(NO3)2.6H2O and Th(NO3)4.5H2O. The adsorption parameters for the two radioelements were determined by application of the Langmuir, Freundlich and Elovich models
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