time petri nets
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2022 ◽  
Vol 183 (1-2) ◽  
pp. 97-123
Author(s):  
Didier Lime ◽  
Olivier H. Roux ◽  
Charlotte Seidner

We investigate the problem of parameter synthesis for time Petri nets with a cost variable that evolves both continuously with time, and discretely when firing transitions. More precisely, parameters are rational symbolic constants used for time constraints on the firing of transitions and we want to synthesise all their values such that some marking is reachable, with a cost that is either minimal or simply less than a given bound. We first prove that the mere existence of values for the parameters such that the latter property holds is undecidable. We nonetheless provide symbolic semi-algorithms for the two synthesis problems and we prove them both sound and complete when they terminate. We also show how to modify them for the case when parameter values are integers. Finally, we prove that these modified versions terminate if parameters are bounded. While this is to be expected since there are now only a finite number of possible parameter values, our algorithms are symbolic and thus avoid an explicit enumeration of all those values. Furthermore, the results are symbolic constraints representing finite unions of convex polyhedra that are easily amenable to further analysis through linear programming. We finally report on the implementation of the approach in Romeo, a software tool for the analysis of time Petri nets.


Author(s):  
Karen Godary-Dejean ◽  
Hélène Leroux ◽  
David Andreu
Keyword(s):  

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Anis M’halla

In transport systems, all equipment requires maintenance, which directly affects the machine’s availability and consequently the planned transport schedule. The purpose of this paper is to carry out a method for integrating recovery jobs in railway systems. The proposed method allows the insertion of preventive and corrective maintenance operations when the transport equipment is available in order to minimize periods of inactivity, avoid catastrophic scenarios, and maintain stability and safety of the studied networks. A computing algorithm, allowing insertion of the planned recovery tasks in periods of metro availability, without changing the initial scheduling solution, is established. Finally, we illustrate the implementation of the proposed approach on Tunisian Sahel railway transport networks.


Author(s):  
Naima Jbeli ◽  
Zohra Sbai

Time Petri nets (TPN) are successfully used in the specification and analysis of distributed systems that involve explicit timing constraints. Especially, model checking TPN is a hopeful method for the formal verification of such complex systems. For this, it is promising to lean to the construction of an optimized version of the state space. The well-known methods of state space abstraction are SCG (state class graph) and ZBG (graph based on zones). For ZBG, a symbolic state represents the real evaluations of the clocks of the TPN; it is thus possible to directly check quantitative time properties. However, this method suffers from the state space explosion. To attenuate this problem, the authors propose in this paper to combine the ZBG approach with the partial order reduction technique based on stubborn set, leading thus to the proposal of a new state space abstraction called reduced zone-based graph (RZBG). The authors show via case studies the efficiency of the RZBG which is implemented and integrated within the 〖TPN-TCTL〗_h^∆ model checking in the model checker Romeo.


Author(s):  
Nabil Jerbi ◽  
Simon Collart-Dutilleul

This paper is dedicated to the study of constraints violation in manufacturing workshops with time constraints. In such systems, every operation duration is included between minimal and maximal values. P-time Petri nets are used for modeling. A new theorem is introduced, constituting a decision tool about the occurrence of constraints violation at the level of a synchronization transition when various types of time disturbances occur. It shows the robustness properties of a manufacturing system on a range that may include delay and advance disturbances. The theoretical result is illustrated step by step on a given workshop. Two other lemmas are elaborated contributing to the study of the constraints violation problem. The final goal is to generalize the robustness property towards simultaneous occurrence of two delays at two points of the system, each having its own robustness range.


Industrial Internet of Things (IIoT) services composition rely on composing existing IoT services in industrial context in order to obtain an overall service with added value. The composite service’s behavior is extremely influenced by the time, availability, and accuracy of the unitary services. Thus, it is extremely important to guarantee a provision of IIoT services as expected during the modeling phase. For this, we lie on formal verification to check all the possible scenarios before to pass through IIoT services provision. We propose first to model each process involved in the composition by open Time Petri Nets. These nets offer interface places for the purpose of process communication with the other processes. Then the composition of open Time Petri Nets is guaranteed via superimposing the interface places and thus obtaining a Time Petri Net modeling the composite process. Finally, control and operational behaviors of IIoT services composition formally checked after being specified in an expressive fragment of TCTL temporal logic


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