scholarly journals Modeling and Robustness Study of Railway Transport Networks Using P-Timed Petri Nets

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Anis Mhalla ◽  
Mohanned Gaied
Keyword(s):  
Petri Nets ◽  
Traffic Management ◽  
Control Strategies ◽  
Discrete Event ◽  
Transport Systems ◽  
Population Mobility ◽  
Railway Transport ◽  
Transport Networks ◽  
Modeling And Analysis ◽  
Increasing Demand

The importance of public transport systems continues to grow. These systems must respond to an increasing demand for population mobility and traffic disturbances. Rail transport networks can be considered as Discrete Event Systems (DES) with time constraints. The time factor is a critical parameter, since it includes dates to be respected in order to avoid overlaps, delays, and collisions between trains. P-time Petri Nets have been recognized as powerful modeling and analysis tools for railway transport systems. Temporal disturbances in these systems include railway infrastructure, traffic management, and disturbances (weather, obstacles on the tracks, malice, social movement, etc.). The developments presented in this paper are devoted to the modeling and the study of the robustness of the railway transport systems in order to evaluate the stability and the efficiency of these networks. In this study two robust control strategies towards time disturbances are presented. The first one consists of compensating the disturbance as soon as it is observed in order to avoid constraints violation. The second one allows generating, by the control, a temporal lag identical to the disturbance in order to avoid the death of marks on the levels of synchronization transitions of the P-time Petri net model.

Robust control for railway transport networks based on stochastic P-timed Petri net models

2019 ◽  
Vol 233 (7) ◽  
pp. 830-846
Author(s):  
Mouhaned Gaied ◽  
Anis M’halla ◽  
Dimitri Lefebvre ◽  
Kamel Ben Othmen
Keyword(s):  
Robust Control ◽  
Petri Nets ◽  
Discrete Event Systems ◽  
Optimization Problems ◽  
Discrete Event ◽  
Transport Systems ◽  
Time Constraints ◽  
Railway Transport ◽  
Transport Networks ◽  
Event Systems

This article is devoted to the modeling, performance evaluation and robust control of the railway transport network in Sahel Tunisia. The regular increase in the number of passengers makes the management of transportation systems more and more complex. Railway transport requires specific needs. Indeed, many decision and optimization problems occur from the planning phase to the implementation phase. Railway transport networks can be considered as discrete event systems with time constraints. The time factor is a critical parameter, since it includes schedules to be respected in order to avoid overlaps, delays and collisions between trains. The uncertainties affect the service and the availability of transportation resources and, consequently, the transport scheduling plan. Petri nets have been recognized as powerful modeling and analysis tools for discrete event systems with time constraints. Consequently, they are suitable for railway transport systems. In this article, stochastic P-time Petri nets are used for the railway transport networks in Sahel Tunisia. A global model is first detailed. Then, this model is used to analyze the network traffic and evaluate the performance of the system. Robustness again disturbances is introduced and a control strategy is developed to reduce the consequences of the disturbances in order to maintain the expected schedule.

scholarly journals A Monitoring Approach Based on Fuzzy Stochastic P-Timed Petri Nets of a Railway Transport Network

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Anis M’hala
Keyword(s):  
Petri Nets ◽  
Stochastic Petri Nets ◽  
Transport Systems ◽  
Railway Transport ◽  
Timed Petri Nets ◽  
Transport Networks ◽  
Railway Network ◽  
Fuzzy Petri Nets ◽  
Traffic Disturbance

This paper proposes a monitoring approach based on stochastic fuzzy Petri nets (SFPNs) for railway transport networks. In railway transport, the time factor is a critical parameter as it includes constraints to avoid overlaps, delays, and collisions between trains. The temporal uncertainties and constraints that may arise on the railway network may degrade the planned schedules and consequently affect the availability of the transportation system. This leads to many problems in the decision and optimization of the railway transport systems. In this context, we propose a new fuzzy stochastic Petri nets for monitoring (SFPNM). The main goal of the proposed supervision approach is to allow an early detection of traffic disturbance to avoid catastrophic scenarios and preserve stability and security of the studied railway networks. Finally, to demonstrate the effectiveness and accuracy of the approach, an application to the case study of the Tunisian railway network is outlined.

scholarly journals Static Integration Based on Stochastic P-Time Petri Nets of Maintenance Scheduling for Railway Transport Equipment

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Anis M’halla
Keyword(s):  
Petri Nets ◽  
Maintenance Scheduling ◽  
Transport Systems ◽  
Time Petri Nets ◽  
Railway Transport ◽  
Transport Networks ◽  
Transport Equipment ◽  
Corrective Maintenance ◽  
Railway Systems ◽  
Computing Algorithm

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.

scholarly journals Supervisors of Petri Nets

2019 ◽  
Vol 27 (45) ◽  
pp. 33-41
Author(s):  
Jana Flochová ◽  
Tomáš Lojan
Keyword(s):  
Petri Nets ◽  
Communication Networks ◽  
Supervisory Control ◽  
Manufacturing Systems ◽  
Discrete Event Systems ◽  
Discrete Event ◽  
Modeling And Analysis ◽  
Industrial Systems ◽  
Software Application ◽  
Event Systems

Abstract The design and operation of modern industrial systems require modeling and analysis in order to select the optimal design alternative and operational policy. Discrete event system models are encountered in a variety of fields, for example computers, communication networks, manufacturing systems, sensors or actuators, faults diagnosis, robotics and traffic. The paper describes principles and methods of supervisory control of discrete event systems initiated by Ramadge and Wonham. Three supervisory control methods based on the Petri net models are introduced, and the key features of the Petri tool software application for the supervisory control of discrete event systems modeled by Petri nets are highlighted.

Method for evaluating the landing aircraft sequence under disturbed conditions with the use of Petri nets

2016 ◽  
Vol 120 (1227) ◽  
pp. 819-844 ◽  
Author(s):  
J. Skorupski ◽  
A. Florowski
Keyword(s):  
Petri Nets ◽  
Traffic Management ◽  
Control Strategies ◽  
Air Traffic ◽  
Control Algorithms ◽  
Air Traffic Controller ◽  
Airport Capacity ◽  
Evaluation Scores ◽  
Random Disturbances ◽  
Different Characteristics

ABSTRACTOne of the important tasks that air traffic management services are faced with today is the task of maximising airport capacity. This can be achieved at the tactical level through proper organisation of air traffic around an airport. In recent years, many methods and algorithms for scheduling aircraft landings have been developed; they take into account various optimisation goals. The aim of this paper was to create a method that would allow one to evaluate landing aircraft sequences resulting from these control algorithms, especially in the presence of random disturbances. This method involves modelling the landing aircraft sequence by using Petri nets. The model and the computer tool that have been developed make it possible to take into account different kinds of disturbances and examine the effectiveness of various control strategies under these conditions. This paper presents two experiments that test disturbances with different characteristics and of different intensities. It has been shown that small but more frequent disturbances lead to the worsening of evaluation scores for a given sequence to a lesser extent than rare but larger disturbances. This is particularly important for control algorithms in which the focus is on high aircraft density. If the type of particular disturbances is properly assessed, then it will be possible to assist the decision-maker (air traffic controller) by providing him/her with quantitative evaluations of possible solutions.

scholarly journals Robust control strategies facing disturbances in Railway Transport Networks

2021 ◽  
Vol 14 (42) ◽  
pp. 3133-3143
Author(s):  
Anis Mhalla ◽  
◽  
Mohanned Gaied ◽  
Dimitri Lefebre
Keyword(s):  
Robust Control ◽  
Control Strategies ◽  
Railway Transport ◽  
Transport Networks

Hybrid adaptive Petri nets: a conceptual framework for partial fluidization of Petri nets

1970 ◽  
pp. 50
Author(s):  
E. Fraca ◽  
J. Júlvez ◽  
M. Silva
Keyword(s):  
Petri Nets ◽  
Petri Net ◽  
Dynamic Systems ◽  
Discrete Event Systems ◽  
Discrete Event ◽  
Modeling And Analysis ◽  
Analysis Techniques ◽  
High Transition ◽  
Large Systems ◽  
Event Dynamic

Petri nets (PNs) constitute a well known family of formalisms for the modeling and analysis ofDiscrete Event Dynamic Systems (DEDS). As most formalisms for discrete event systems, PNssuffer from the state explosion problem, which renders enumerative analysis techniquesunfeasible for large systems. A technique to overcome the problem is to relax integralitycontraints of the discrete PN model, leading to continuous PN. This relaxation highly reducesthe complexity of analysis techniques but may not preserve important properties of theoriginal PN system such as deadlock‐freeness, liveness, reversibility, etc. This work focuses onHybrid Adaptive Petri nets (HAPNs), a Petri net based formalism in which the firing oftransitions is partially relaxed. The transitions of a HAPN can behave in two different modes:continuous mode for high transition workload, and discrete in other case. This way, a HAPN isable to adapt its behaviour to the net workload, it offers the possibility to represent morefaithfully the discrete model and use efficient analysis techniques by behaving as continuouswhen the load is high. Reachability space and the deadlock‐freeness property of hybridadaptive nets is studied in this work.

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