Petri Nets

Policies are increasingly used to manage large-scale distributed system. They usually adopt ECA rules that can 't express system i state transitions, enable policy servers to perform jlexible actions or cooperate eflciently. In this paper; a logic-based policy definition language LPDL is proposed. We define LPDL'S syntax, execution model and its semantic that provides a formal framework for policy-based network management. LPDL is proved to have Petri Net i expressive power and Turing Machine b computing power. Administrator can use LPDL to describe system b analysis and decision functions or encapsulate them into physical codes jlexibly based on actual need. Finally, a Cooperative Network Management Framework ( C N W ) , its protoqpe and application are presented to show that LPDL can meet the requirements of network management j. dynamic growth.

In Multi-Agent System (MAS), developers concentrate on creating design models and evolving them, from higher level models to lower level models, in several steps. Considerable part of MAS implementations is automatically produced from the design models. If a design model contains faults, they are passed to the generated implementations. Practical model validation techniques are required to discover and delete faults in abstract design models.

Dawson request a method for maually detecting deadlocks for his system. This reply provides a dynamic and interactive Petri Net diagram for his system. With this diagram, you can fire every enabled transition and see the corresponding marks and status update. You can also delegate the selection of an enabled transition and firing the selected enabled transition to the computer; in this case a deadlock may be reached (if there is one) via "simulation".

Abstract Programmable Logic Controllers (PLC) have been used in industrial environment to control several different tasks. Such devices can be programmed using one of the languages specified in the IEC 61131–3 standard, such as Ladder or Functional Logic ...

Synthesis of asynchronous circuits from Signal Transition Graphs (STGs) involves resolving state coding conflicts. The refinement process is generally done automatically using heuristics and often produces sub-optimal solutions, which have to be corrected manually. This paper presents a framework for an interactive refinement process aimed to help the designer. It is based on the visualization of conflict cores, i.e., sets of transitions causing coding conflicts, which are represented at the level of finite and complete prefixes of STG unfoldings.

In flexible manufacturing systems (FMS), each job is formed of a set of operations that should be executed consecutive. Determining the sequence of operations and assigning proper machine to each operation are two important problems in scheduling FMS's. This is an NP-hard problem. Recently using heuristic methods, numerous algorithms are presented for solving this problem. In this paper for scheduling of flexible manufacturing systems, a new algorithm called hybrid genetic algorithm-Petri net (HGA-PN) is presented using timed Petri net and combinational genetic algorithm. In our purposed algorithm, first the flexible manufacturing system is modeled by using timed Petri net, and then an appropriate scheduling is manufactured using combinational genetic algorithm. The experimental results illustrates that our proposed algorithm has higher efficiency over other existing algorithms.

The fusion of mechatronics, communication, control and information technologies has allowed the introduction of new automation paradigms into the production environment. The virtualization of the production environment facilitated by the application of the service-oriented architecture paradigm is one of major outcomes of that fusion. On one side, service-oriented automation works based on exposition, subscription and use of automation functions represented by e.g. web services. On the other side, the evolution of traditional industrial systems, particularly in the production area, as a response to architectural and behavioural (functional) viewpoints of the ISA95 enterprise architecture, where a close inter-relation between SCADA, DCS and MES systems facilitate the management and control of the production environment. Automation functions are increasingly performed by the composition and orchestration of services. Among other methods, the application of formal Petri net based orchestration approaches is being industrially established. This paper presents the major characteristics that such a Petri net based orchestration presents when it is developed, implemented and deployed in an industrial environment.

Software agents are a means to support socio-technical decentralised systems that increase the complexity of daily life. Designing multi-agent systems involves modelling methods for which it is currently not possible to check for soundness before a technical implementation. To improve the design process, the agent models require a mapping to a formalisation that is sufficiently expressive to represent equivalent model properties. The formalized presentation must cater for evaluating the model soundness, simulation and performance experimentation with different test data. The paper gives a set of mapping heuristics from agent models to a sufficiently expressive formalisation representation that follows a real life running case stemming from the healthcare domain.

This paper is devoted both to the study of observability criteria and the design of observers in the continuous Petri net setting. The concept of structural observability, regarding the possibility of estimating the marking of places, i.e., the system state, for any speed of the transitions is introduced and studied for the subclass of join-free Petri nets (JF). For non-join-free Petri nets, conditions to compute suitable state estimates are established. The proposed observers are piecewise linear systems that assure the continuity of the estimate even when a switch occurs. The system simulation may allow us to estimate even the unobservable space of the net system during a given time period.

According to our recent proposal, an information system is a combination of a process model captured as a Petri Net with Identifiers, an information model specified in the first-order logic over finite sets with equality, and a specification of how the transitions in the net manipulate information facts. The Information Systems Modeling (ISM) Suite is an integrated environment for developing, simulating, and analyzing models of information systems, released under an open-source license. This paper presents the basic features of the ISM Suite.

In this paper, we present our methodology proposal for cooperative remote systems modeling. Its aim is to develop models of existing or planned cooperative systems. These models are used to specify systems or to create dynamic working simulations. Comparative performances are deduced from the latter. The associated meta-model proposal is based, among other things, on the use of multi-agent systems, Petri nets and stochastics Petri nets. After having described the whole methodology concepts, we show a set of general results extracted from simulations.

This paper presents a fault-tolerant distributed system designed for real-time control applications (REBUS), which is one of the research basis of the industrial real-time system MODUMAT 800. It is made up of functional units, i.e., programmable multiloop regulators and operator displays, linked together by a communication structure. The communication hardware consists of a set of serial bus interface boards, one per functional unit, loosely coupled together by a double serial bus and linked to their functional units by a private parallel bus.

This paper addresses fault diagnosis in dynamic systems represented by discrete state-space models. The main idea of the paper is to propose a systematic way to implement a Petri net-based fault diagnosis system. This procedure consists of three main steps. In the first step, a fault diagnosis system is built based on the Luenberger observer. In the second step, the obtained fault diagnoser equations are transformed to a suitable format. Finally, in the third step, the obtained equations are implemented by a Petri net called continuous-time delay Petri net (CTDPN) that can realize difference equations. Based on this method, a systematic approach is proposed for realizing a classical fault diagnoser by CTDPN. By integrating the concept of state-space observers and PNs in this paper, new and effective methods are developed for the analysis and fault diagnosis of systemsknown as hybrid systems-that have both continuous and discrete variables. The performance of the proposed method is thoroughly investigated, and the obtained results show that the proposed CTDPN can precisely detect the occurred faults, their types and their occurrence time instances.

In this paper we deal with the problem of estimating the marking of a labeled Petri net system based on the observation of transitions labels. In particular, we assume that a certain number of transitions are labeled with the empty string ε, while a different label taken from a given alphabet is assigned to all the other transitions. Transitions labeled with the empty string are called silent because their firing cannot be observed. Under some technical assumptions on the structure of the Tε -induced subnet, where Tε denotes the set of silent transitions, we formally prove that the set of markings consistent with the observed word can be represented by a linear system with a fixed structure that does not depend on the length of the observed word.

Today, the world is moving towards becoming smart. Tools and equipment are somewhat smart and now it's time to use them for making smart the organizations and special places. Integration of smart devices and using them in a special place makes it to be smart place. Human is always looking for the best decision as soon as possible in an emergency situation. This becomes more important when we speak about human lives. Having a smart system for hospitals can reduce the concerns. In this paper first the ideas to have a smart hospital are presented and then a Petri Net model is designed for it. The detailed rules for design of Petri Net model make it easy to transform the initial heuristic selection criteria in formalized procedures of model construction. The model proposed in this paper can be used in different levels with proper and purposefully development.

Examples of live and quasi-live Petri Nets have been created in response to a request for examples form Salim (2018) at Comsputer Science Stack Exchange. The exmaples are dynamic and interactive PDF form applications that use JavaScript and the Acrobat/JavaScript API.

After a survey of some approaches for modeling hybrid systems by means of Petri nets (t-time Petri nets, colored Petri nets, hybrid Petri nets and differential predicate transition nets), this paper illustrates how these formal models can be used for simulation and validation. It is shown how it was possible to use aggregated qualitative models concurrently with detailed ones.

Attiq_Lone (2019) seems to be having a difficult time writing a sketch. He may find it worthwhile to draw a Petri Net diagram of his system and add the logic of his system as annotations to the diagram. Then write the sketch based on the Petri Net diagram and its annotations. It is the method I used to write the sketch for his system and the method I would use for all of my applications.

Contemporary workflow management systems are driven by explicit process models, i.e., a completely specified workflow design is required in order to enact a given workflow process. Creating a workflow design is a complicated time-consuming process and, typically, there are discrepancies between the actual workflow processes and the processes as perceived by the management. Therefore, we have developed techniques for discovering workflow models. The starting point for such techniques is a so-called "workflow log" containing information about the workflow process as it is actually being executed. We present a new algorithm to extract a process model from such a log and represent it in terms of a Petri net. However, we will also demonstrate that it is not possible to discover arbitrary workflow processes. In this paper, we explore a class of workflow processes that can be discovered. We show that the -algorithm can successfully mine any workflow represented by a so-called SWF-net.

Computer Automated Multi-Paradigm Modelling (CAM-PaM) is an enabler for domain-specific analysis and design. Traffic, a new untimed visual formalism for vehicle traffic networks, is introduced. The syntax of Traffic models is meta-modelled in the Entity-Relationship Diagrams formalism. From this, augmented with concrete syntax information, a visual modelling environment is synthesized using our CAMPaM tool AToM 3 , A Tool for Multi-formalism and Meta-Modelling. The semantics of the Traffic formalism is subsequently modelled by mapping Traffic models onto Petri Net models. As models' abstract syntax is graph-like, graph rewriting can be used to transform models. The advantages of a domain-specific formalism such as Traffic as opposed to a generic formalism such as Petri Nets are presented. We demonstrate how mapping onto Petri Nets allows one to employ the vast array of Petri Net analysis techniques. A Coverability Graph is generated and conservation analysis is automated by transforming this graph into an Integer Linear Programming specification.

This paper focuses on the use of Petri nets (PN) to model the control of signalized intersections. The application of PN to an eight-phase traffic signal controller is illustrated. Structural analysis of the control PN model is performed to demonstrate how the model enforces the traffic operation safety rules. This is followed by a discussion of why this modeling tool has future value as the use of more advanced control strategies continue to expand.

This work intends to carry out a preliminary study about the interference and benefits of installing a safety net in the Equalization and pH control sub-processes of the effluent treatment plant of the Laboratory of Automation and Industrial Networks (LARI), using Petri Net modeling with the help of the software CPNTools to perform the necessary tests until a conclusion is reached.

This article outlines the utilization of Petri nets as a computerized process modeling and analysis tool for the study of the Edmonton Mail Processing Plant (MPP). Development of new systems or designing improvement in existing system-such as the MPP-are some of the challenges faced by decision makers and managers on a regular basis in the industry. In order to make prudent decisions, modeling and analysis of the underlying processes that constitute new or existing systems has become essential. Usually process modeling and analysis is performed by initially developing a graphical portrayal of the process and then by dynamically studying the response of the process to external and internal factors. In this article an overview of Petri net based process modeling and analysis is provided. Petri net is a formal graphical modeling tool that can be efficiently utilized as a process modeling and analysis tool because it can graphically portray and dynamically simulate a process in an integrated manner. The objective of this article is to highlight the symbolic graphic format and dynamic simulation capabilities of Petri nets. The article contributes significantly in the area of computer based decision making and provides value to practicing engineers and project managers who manage complex tasks. ᭧ (A. Sawhney) www.elsevier.com/locate/advengsoft A. Sawhney et al. / Advances in Engineering Software 30 (1999) 543-549 546 Raw Mail Cull Culled Mail Cancellation 9 7 % 3 % Ready for M L O C R & O C R Ready for rerun Rerun Culling Machine Fig. 3. Petri net model of the ''culling and cancellation'' activity. 6 5 % 3 5 % Ready f o r M L O C R Ready for OCR Processing b y M L O C R Processing by OCR 9 5 % 5 % 1 0 % 9 0 %

The aim of this survey is to introduce Computer science/Petri nets specialists to the basic system level issues brought up by the development of Flexible Manufacturing and how Petri nets are used to aid the production engineers in their work. After some terminology concerning production engineering, the hierarchical decision and control level is briefly reviewed. Finally, the role and the presence of nets in CAE (Computer Aided Engineering) and in CAM (Computer Aided Manufacturing) for FMSs (Flexible Manufacturing Systems) are considered. From the design point of view, the use of nets have many advantages in modeling, qualitative analysis, performance evaluation and code generation. From the control of the plant perspective, scheduling on nets models, the coordination of the plant (global and partial) and the presence of nets in the local control level are discussed. Petri nets theory presents a relatively mature body, nevertheless efficient performance evaluation (even for P/T net models) and qualitative analysis of highlevel net models still requires important developments. The Babel-Tower-impression that the Petri net newcomer may have looking at the myriad of so-called high-level-nets formalisms may initially produce some kind of rejection. In any case, it is our opinion that Petri nets appears as a key formalism to describe, analyze and implement the control of FMSs. The merging of Petri nets and knowledge based techniques seems to be very promising to deal with large complex discrete event dynamic systems such as FMSs. Petri Nets and Flexible Manufaturing (rebuilt version January 24, 2005) Gentina, P. Muro, J.L. Villarroel, K. Voss and many other persons. 6 References. 6.1 References on general notions in manufacturing systems. BAL 69 Balas E., Machine sequencing via disjunctive graphs: an implicit enumeration algorithm, Oper. Res. 17 No 6. ERS 79 Erschler J., Fontan G., Roubellat F., Potentiels sur un graphe non conjonctif et analyse d'un problème d'ordonnancementà moyens limités, RAIRO, 13 No 4. ERS 86a J. Erschler, F. Roubellat, V. Thomas: Real-time Production Scheduling for Parts with Limit Times. TIMS/ORSA Joint National Meeting, Los Angeles, April. ERS 86b J. Erschler, P. Esquirol: Decision-aid in job-shop scheduling: a knowledge based approach. SIL 85 M. Silva: Las redes de Petri en la Automática y la Informática. Ed. AC, Madrid. SIL 87a M. Silva: Towards a synchrony theory for P/T nets. Concurrency and Nets (K. Voss et al., eds). Springer-Verlag, pp. 435-460. SIL 88 M. Silva, J.M. Colom: On the computation of structural synchronic invariants in P/T nets.

What is the background of this tutorial? During the last decade, the integrative research area of systems biology has constantly been gaining more importance. Experimental and computational approaches are combined to investigate biological systems systematically. To understand biology on its system level, the structural and dynamic properties of regulatory networks in biological systems have to be represented by a model describing the involved species and their interactions. Petri net theory offers the possibility to construct and analyse such models and to represent their structural and dynamic properties by various techniques.

Who should read this tutorial? This tutorial addresses scientists who are looking for an easy and intuitive way to translate a biological system into a Petri net model at an arbitrarily chosen level of abstraction with the option of representing time and space-dependent processes. The tutorial is equally suitable for experimental and theory oriented bio-scientists. The examples given in the tutorial can be used by the interested reader to model her/his biological system.

What can I learn? The tutorial offers an introduction to the Petri net formalism, how to construct a model of a biological system, analyse its structure and dynamic behaviour regarding time-dependent behaviour, which is shown by several intuitive examples. At the end of the tutorial, you will be able to model a biological system on your own using Petri nets. You will also know how to analyse the structure of your model, how to interpret the results and how to perform simulation studies to investigate the time-dependent dynamic behaviour. Also, we also provide a chapter about model checking, which might be helpful to evaluate your model by verifying specified properties that you are interested in. We also show how to use the two Petri net tools Snoopy [19] and Charlie [8]. Based on these instruments you will be able to enhance your knowledge about the modelled biological system and to draw new conclusions from that.

Why should I use Petri nets? The graphical notation and construction of Petri nets allow you to easily and intuitively construct models of biological systems and to characterise the structure, behavioural properties related to the structure and time-dependent dynamic behaviour of a model by several related techniques. Petri nets can describe concurrent and parallel processes, as well as communication and synchronisation in bipartite systems regardless of the abstraction level in a comprehensive and mathematically correct model [12]. Time, as well as space aspects, can be modelled by a Petri net. Several specialised Petri net classes are available to describe dierent scenarios and to consider dierent simulative approaches. Therefore, the kinetics of the qualitative Petri net model can be considered as stochastic, continuous or as a mixture of both (hybrid) [12]. In silico experiments with Petri net models, permit to analyse a biological system systematically by applying structural as well as dynamic analysing techniques to investigate perturbations. From the obtained results new insights can be achieved by the biological system. Thereby, you can increase your understanding, reveal gaps in knowledge, and detect missing and essential components. Based on a valid model it is possible to predict the system behaviour. This might be helpful to investigate pathological states and their molecular basis aimed at identifying potential targets to develop therapeutical intervention strategies. The Petri net formalism offers quite a few advantages over other and more broadly used modelling frameworks. The different Petri net classes are interconvertible with each other without changing the qualitative structure. Due to the graphical visualisation of molecular networks by Petri nets, a bioscientist can intuitively understand the modelled mechanisms. The user does not have to deal with many dierent representations of a molecular network which do not obviously correspond to each other like a biological cartoon, the structure of the biological network, the mathematical equations (stochastic, continuous, etc.) and the implementation of the equations. Besides, the transformation of a molecular network represented by a Petri net into e.g. ODE equations is unique, but not vice versa [24]. Several reliable analysis tools have been developing to investigate qualitative and quantitative properties of Petri nets by structural analysis, simulation of the time-dependent dynamic behaviour and model checking.

What is the scheme of this tutorial? First of all, you will learn all the basics about the Petri net formalism motivated by small biological examples that are easy to understand. Next, you will see how to analyse the structure of a model and how to interpret the obtained results and their biological meaning. Afterwards, you will learn how to perform simulations with your model. We also offer a chapter about model checking, where you can learn how to verify specific properties of your model. Then, we introduce the two Petri net tools Snoopy [19] and Charlie [8]. All sections, where theoretical concepts are explained, are divided into an informal and a formal part. We start with an informal introduction, where we explain the basics and the biological relations. Subsequently and to be complete, we give the formal definitions and a small help on \how to read" the definitions at the end of the section.

What tools do I need? Several tools are available to model biological systems, simulate their time-dependent dynamic behaviour and analyse their structure. Here, we use the Petri net editor Snoopy [19] to model biological systems and simulate/animate their time-dependent dynamic behaviour. Charlie [8] is used to analyse the Petri net structure. Both software tools were developed at the chair of Data Structures and Software Dependability at the Brandenburg University of Technology Cottbus and are freely available for non-commercial use. You can download them at http://www-dssz.informatik. tu-cottbus.de/DSSZ/Software/Software [1].

We know that increasing fuel consumption, high environmental pollution and time wasting are the visible results of high traffic density. Developing new directions or even highways is an alternative way to solve this problem. It may add several junctions. Therefore, we provided a method which declines the waiting time behind the red color in the first phase through controlling Fuzzy logic traffic light and following a fair performance. The density queue behind the red color and also the density of passing cars are the arrival parameters in this method. This Fuzzy controller system with receiving those two traffic parameters in regular condition provided timing operation according to the level of traffic or in front of a special traffic mode that will change traffic light condition. Junction controlling problem is raised in the second phase which has specific importance, because their usual operation will cause problems if they remain without control. This not only does not help to traffic managing, but also leads traffic towards deadlock conditions. Therefore, the second phase started through sending the time parameter to the control center (which is timing by Fuzzy traffic light). Then the control center sends appropriate output to the next traffic light after necessary validation of parameter value. We simulate Fuzzy intelligent traffic lights and junction controller systems by CPN Modeling tool to investigate the accuracy of system performance.

Resumo-Neste trabalho apresentamos uma técnica para a tradução de programas Ladder para modelos em Redes de Petri Coloridas (CPN). Ladderé usada no desenvolvimento de software para Controladores Lógico Programáveis, dispositivos usados na automação industrial (e.g.; plantas químicas, de gás e de petróleo). Neste contexto são necessários alto nível de confiança e de segurança, pois a ocorrência de faltas pode resultar em grandes perdas financeiras e até mesmo de vidas humanas. Assim, aspectos formais inerentesàs CPN e seu suporte ferramental podem ser usados para garantir o nível de confiança desejado de tais sistemas.

Petri nets (PNs) are widely used to model discrete event dynamic systems (computer systems, manu- facturing systems, communication systems, etc). Continuous Petri nets (in which the markings are real numbers and the transition firings are continuous) were defined more recently; such a PN may model a continuous system or approximate a discrete system. A hybrid Petri net can be obtained

Petri Nets is a family of modeling formalisms, with different interpretations and abstraction levels; the Petri nets family of modeling formalisms includes ordinary Petri Net, generalized Petri Net, and also all other extensions e.g. Colored Petri Net, Petri Net with priority, and Petri Net with inhibitor arcs. The availability of different formalisms of the Petri Net family is considered as its main strength, since a discrete system can be modeled with different Petri Net formalism, in order to achieve different abstraction levels and different interpretations. This work presents an application of a new Petri Net simulator known as GPenSIM; GPenSIM is used to model the classical Cigarette Smokers' Problem, using the different Petri Net extensions implemented in GPenSIM. Thus, this work can be considered as a benchmark to test the strengths and weakness of GPenSIM, in modeling and simulation of discrete event systems.

Manufacturing and production plants operate physical assets that deteriorate with usage and time, thus, maintenance actions are required to restore the assets back to their original predetermined operational conditions. But since, organizational resources are limited and scarce. The objective of an effective maintenance program is to minimize total cost of inspection and repair, and equipment downtime. In this paper, we describe a new multicriteria optimization framework for deriving optimal maintenance schedules for preventive maintenance which considers availability, maintenance cost and life cycle costs as the criteria for optimization. The Simulink toolbox of the Matlab has been interfaced with Genetic algorithm for optimization. After getting solution, Stochastic Petri nets has been used to model the system and find out the effect of optimized maintenance schedules on system performance. The application of the proposed framework has been discussed on a practical case of a paper plant.

Over the past two decades, research has focused on simplifying dependability analysis by looking at how we can synthesise dependability information from system models automatically. This has led to the field of model-based safety assessment (MBSA), which has attracted a significant amount of interest from industry, academia, and government agencies. Different model-based safety analysis methods, such as Hierarchically Performed Hazard Origin & Propagation Studies (HiP-HOPS), are increasingly applied by industry for dependability analysis of safety-critical systems. Such systems may feature multiple modes of operation where the behaviour of the systems and the interactions between system components can change according to what modes of operation the systems are in.

MBSA techniques usually combine different classical safety analysis approaches to allow the analysts to perform safety analyses automatically or semi-automatically. For example, HiP-HOPS is a state-of-the-art MBSA approach which enhances an architectural model of a system with logical failure annotations to allow safety studies such as Fault Tree Analysis (FTA) and Failure Modes and Effects Analysis (FMEA). In this way it shows how the failure of a single component or combinations of failures of different components can lead to system failure. As systems are getting more complex and their behaviour becomes more dynamic, capturing this dynamic behaviour and the many possible interactions between the components is necessary to develop an accurate failure model.

One of the ways of modelling this dynamic behaviour is with a state-transition diagram. Introducing a dynamic model compatible with the existing architectural information of systems can provide significant benefits in terms of accurate representation and expressiveness when analysing the dynamic behaviour of modern large-scale and complex safety-critical systems. Thus the first key contribution of this thesis is a methodology to enable MBSA techniques to model dynamic behaviour of systems. This thesis demonstrates the use of this methodology using the HiP-HOPS tool as an example, and thus extends HiP-HOPS with state-transition annotations. This extension allows HiP-HOPS to model more complex dynamic scenarios and perform compositional dynamic dependability analysis of complex systems by generating Pandora temporal fault trees (TFTs). As TFTs capture state, the techniques used for solving classical FTs are not suitable to solve them. They require a state space solution for quantification of probability. This thesis therefore proposes two methodologies based on Petri Nets and Bayesian Networks to provide state space solutions to Pandora TFTs.

Uncertainty is another important (yet incomplete) area of MBSA: typical MBSA approaches are not capable of performing quantitative analysis under uncertainty. Therefore, in addition to the above contributions, this thesis proposes a fuzzy set theory based methodology to quantify Pandora temporal fault trees with uncertainty in failure data of components.

The proposed methodologies are applied to a case study to demonstrate how they can be used in practice. Finally, the overall contributions of the thesis are evaluated by discussing the results produced and from these conclusions about the potential benefits of the new techniques are drawn.