This paper is a contribution for development of a high level of security for the Programmer Logic Controller (PLC). Many industrial adopt the redundant PLC architecture (or Standby PLC) designed to replace the failed (out of order) PLC without stopping associated automated equipments. We propose a formal method to choose a Standby PLC based on probability study, by comparing normal functioning to misbehavior one leading to residue generation process. Any generated difference reveals a presence of anomaly. The proposed method begins by listing all PLC components failures leading to their stopping according to failures criticalities. Two models; functional and dysfunctional are obtained by using formal specifications. Probability’s calculus of dysfunction of each Standby PLC is obtained by the sum of the probabilities of dysfunction of its critical components. These probabilities are allocated each transition which leads to the dysfunction in the dysfunctional model. The dysfunctional model is obtained by using the FMECA method (Failure Modes, Effects and Criticality Analysis). We shall see that this global vision of functioning of the whole PLC leads to a higher level of security where the chosen Standby PLC works continuously.

In this paper, we will present a state of the art in using multi-agent technology for wireless sensor networks where the main goal is the conception of software architecture and the network organization dedicated to optimization, performance analysis, and monitoring. Then we explore in particular, the issues of topology control and works in this field and the use of multi-agent systems. Finally we will propose an agent based algorithm for fault tolerance and topology control in a wireless sensor network. Our proposal consists to embed an agent at each node that is responsible for selecting its parent node or the next hop to the sink when transferring packets. The process of parent change is based on the computation of a fault tolerance degree which is calculated periodically by the agent in cooperation with neighboring nodes, in addition to other parameters such as the number of hops, the energy and the quality of link. Simulation results show that this method of changing parent allows a fault tolerant network with enhanced life time compared with the collect tree protocol CTP used for data gathering in a wireless sensor network.

Hybrid dynamic systems are analyzed through linear hybrid automaton. In this paper, we propose a mapping algorithm to deal with a new Continuous elementary HPN. The method shown enables us to analyze some system properties using a linear hybrid automaton generated by a mapping process. The application involves a water system of three tanks, which is analyzed by a PHAVer (Polyhedral Hybrid Automaton Verifier) software tool. Its effectiveness is illustrated by numerical simulation results.