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Abstract:In literature, most papers examine several stochastic demand processes where order lead times are constant. In reality, manufacturing firms use inventory management software, especially MRP, which ignored lead time uncertainty. It is true that in certain special cases, lead time uncertainty has essentially no effect and can be ignored. Nevertheless more often, lead time fluctuations strongly degrade tools performance and cause high production costs, just as demand uncertainty does. Seemingly, uncertainty has been neglected for a long time in favour of studying demand uncertainties. Industry agrees that it is overdue and there is a need to rectify this oversight. Nowadays, this gap in research activity begins to be filled in order to respond to companies having non-deterministic lead-times constraints. This paper reviews some of existing literature of supply planning tools under uncertainty of lead times. The extensive literature review that we compiled consists of citations from 1970 to 2012. A classification scheme for supply planning under uncertainty is defined.

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In most wireless sensor network (WSN), energy is a limited resource. Indeed, a sensor has a limited power source (like a battery). When this power source is empty, the sensor stops working. In this paper, we will present the modeling of a multi-objective problem. The first objective is the maximization of the coverage of the area under time, the second objective is the maximization of the lifetime of the network depending on coverage, and finally the minimization of the financial cost (i.e. the number of sensors). The resolution of this problem will be done by multi-objective algorithm NSGA-II [6], SPEA-II [5] and multi-objective ant colony optimization (MOACO) [8].

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