Modelling passenger flows at a transport interchange using Petri nets

With the aim of solving the problems of the Petri nets to the place/transition nets automatic conversion and realization of Petri nets parallel control and running, the algorithm is proposed to transform Color Petri net systems transform into P/T nets. The algebraic model of colored Petri nets and P/T nets, and its intrinsic mechanism is analyzed, the process and theory verification of the colored Petri nets into P/T nets are given. The colored Petri nets into P/T network algorithm is proposed, through the network model of formal, colored Petri nets correlation matrix pretreatment. Experimental results show that it is an effective method to solve Color Petri Net systems transform into P/T nets, lay the foundation for various senior Petri nets system transformation into P/T nets and achieve the parallelism and simulation of running.

The context of our work is the complex systems simulation. Complex systems modelling and simulation require to take into account the interactions between the different components. For instance, an airport ground traffic simulation requires to model the planes with the pilots, the control tower, the

Specification and properties of a cache coherence protocol model.- GAMERU: A language for the analysis and design of human communication pragmatics within organizational systems.- Recent results on the complexity of problems related to Petri nets.- Algebraic structure of flows of a regular coloured net.- On equivalent execution semantics of concurrent systems.- Mathematical methods for calculating invariants in Petri nets.- On Petri nets with deterministic and exponentially distributed firing times.- An accurate performance model of CSMA/CD bus LAN.- Petri net models for the ?-calculus.- Fair processes.- Operational Petri net semantics for CCSP.- Infinitary languages of Petri nets and logical sentences.- A strong part of concurrency.- Concurrency and continuity.- Parallel systems specifications with coloured Petri nets and algebraic specifications.- Bibliography of Petri nets.

Petri Nets provide a graphical notation for modeling systems and performing analysis. Colored Petri Nets (CPNs) combine the strengths of ordinary Petri Nets with a high level programming language, making them more suitable for modeling large systems. A CPN model is an executable representation of a system that can be analyzed through simulation. CPN models are built using CPN Tools, a graphical software tool and interface used to create, edit, simulate, and analyze models. This tutorial is meant to introduce the reader to the vocabulary and constructs of CPNs and illustrate the use of CPN Tools in creating and simulating models by means of a familiar, simple example. In particular, we show how to create a CPN model of the call center example presented by White and Ingalls in their tutorial Introduction to Simulation.

The travelling salesman problem, which can be solved with various methods, is a traditional and typical problem in artificial intelligence (AI). As an evolution of Petri nets, colored Petri nets (CPN) can be dedicated to modeling and analysis of different systems as a new attempt. The paper shows the brief description of the given problem and CPN, we detail the implementation of the CPN model of the problem and analyze the simulation result. This CPN example shows the potentiality of CPN application in AI.

Petri net (PN) is a classical tool for modeling, simulation, and analysis. With the emergence of distributed manufacturing system (DMS), PN has been evolved into different forms such as colored PN (CPN) and timed PN (TPN). To fulfill the practical requirements, CPN has been extended to a larger and more complex model. Meanwhile, DMS becomes an important issue for industry, and how to model a complex manufacturing network for better throughput needs further investigation. A simple single type of PN only cannot fulfill all contemporary requirements at the same time. This paper proposes a new concept for a new PN-hierarchical timed CPN (HTCPN), which can be a powerful tool for modeling, simulation, and analysis for current large complex distributed manufacturing system. This paper presents a general structure of DMS and uses HTCPN to model the manufacturing system as discrete event with dynamic behavior. The proposed approach shows superiority on modeling large complex manufacturing system as it represents the material flow and transitions clearly and provides overview and detailed description for DMS.

In this work, the analysis of behavioural and structural features of automated systems has been investigated by using coloured Petri Nets (CPNs). CPN is one of the best modelling methods of the automated system. Many features of Petri Nets can be searched by reachability tree and invariants. They also show the features of CPN. Reachability tree shows the markings which can be reached by the net. With P invariants we can determine the correctness of the net. In this work, an algorithm to calculate reachability tree of automated systems is developed. P invariants of CPN is analysed and Martinez-Silva algorithm is applied to CPNs. Time performances of these methods are also determined.

The paper is a partial synthesis of the work that a team within the Faculty of Managerial and Technological Engineering has in the field of modeling and simulation of systems with Petri nets. The paper deals with three issues. The first part is Modeling and simulation of manufacturing systems with timed Petri nets. The first part presents the way in which the performances of some manufacturing systems are evaluated using timed Petri nets. The first example is a manufacturing system specific to the textile industry. The system has three production lines. In this case, the modeling with timed Petri nets allows the analysis of the operation of the flow lines and highlights the bottleneck. Another modeled manufacturing system is specific to a series production, more precisely it refers to the manufacture of gas cookers within a company from Oradea. The model with Petri nets also describes the supply sequences of the stocks of parts and subassemblies. The next modeled system is an automated manufacturing system for the packaging of detergents. The complexity of the Detergent Packing System and the high level of automation, require the use of efficient modeling and simulation methods to verify the validity of the solutions adopted. In this chapter is present the model of a robotic welding cell. The second part of the paper, the transition from timed Petri nets to hierarchical colored Petri nets, shows how Petri nets were developed for a robotic cell for metallographic analysis. The third part is dedicated to modeling with colored Petri nets timed with complex colors of the flexible manufacturing cell A007 within the Department of Industrial Engineering.

Coloured Petri Nets (CPNs) is a language for the modelling and validation of systems in which concurrency, communication, and synchronisation play a major role. Coloured Petri Nets is a discrete-ev...

Analysis of controlled technological systems using high level petri nets

Modern control systems are hybrid – continuous or mixed objects are controlled by discrete controllers. Colored Petri nets are theexcellent mean of simulation of control algorithms. Continuous objects can be described by differential equations. These equations canbe represented as a structural scheme. An interface between those to parts of a model is very important as well as evaluation of the time,because it can be one of the factors of control. The simulation system realized in the program package CENTAURUS-C is presented.Interface between both parts of a model is realized via specialized transition, in Petri net, named – process. Three default real variables– $Out, $In and $Prev are used in the interface. A process can carry the value of $Out into a structure of an object as a step signal andreceive signal from any output of blocks in structure as a value of the variable $In. Value of variable $Prev is a value of $Inremembered on previous step of simulation. Variable $Out can be used in an expression of input chord of a process and init the process.Variables $In and $Prev can be used in guard expression of a process to set the end of a process – firing of the specialized transition.Time in the presented system is an attribute of processes and transitions – delay. The delays of transitions are represented by specialexpressions and can be changed dynamically. Ill. 7, bibl. 11 (in Lithuanian; summaries in Lithuanian, English, Russian).Modern control systems are hybrid – continuous or mixed objects are controlled by discrete controllers. Colored Petri nets are theexcellent mean of simulation of control algorithms. Continuous objects can be described by differential equations. These equations canbe represented as a structural scheme. An interface between those to parts of a model is very important as well as evaluation of the time,because it can be one of the factors of control. The simulation system realized in the program package CENTAURUS-C is presented.Interface between both parts of a model is realized via specialized transition, in Petri net, named – process. Three default real variables– $Out, $In and $Prev are used in the interface. A process can carry the value of $Out into a structure of an object as a step signal andreceive signal from any output of blocks in structure as a value of the variable $In. Value of variable $Prev is a value of $Inremembered on previous step of simulation. Variable $Out can be used in an expression of input chord of a process and init the process.Variables $In and $Prev can be used in guard expression of a process to set the end of a process – firing of the specialized transition.Time in the presented system is an attribute of processes and transitions – delay. The delays of transitions are represented by specialexpressions and can be changed dynamically. Ill. 7, bibl. 11 (in Lithuanian; summaries in Lithuanian, English, Russian).

Matlab/Simulink is an industrial tool that is widely used to design and validate control algorithms for embedded control systems using numerical simulation. A Simulink model of a control system typically defines one or more control algorithms together with their environment. Such models exhibit both discrete and continuous dynamics, simulated by discretizing time. On the other hand, a colored Petri net (CPN) is a well known formalism for modeling behavior of discrete event systems. In this paper, we give a formal semantics to Simulink using the CPN formalism, by describing how Simulink models can be expressed as a CPN.We also show how Petri nets can be simulated in Simulink. Finally, we show how a CPN model can be used for performance analysis of a Simulink model.

Business Environments, such as shops, offices, automation plants, etc., are usually handled by the modeling and execution of business processes using languages such as Colored Petri Nets (CPN). CPN are a mathematical and graphical modeling language with powerful analysis techniques. However, current Petri nets formalisms are not aware of their execution context (i.e., Users and equipment location, temporal and environmental properties, etc.) and therefore it is not possible to manage business processes whose execution adapts to its context. To support this adaptation and make business processes smarter, this paper extends CPN with ontologies. Ontologies are powerful and very expressive techniques for modeling context and storing its data at execution time. To be aware of the current context, a context manager is used to sense the execution context using ubicomp technologies and represent it in the ontologies. This solution not only allows the modeling and execution of context-adaptive Petri nets, but also improves system design, reuse, and maintenance by dealing with context and business behavior as separate concerns.

We propose rewriting logic as a unifying framework for a wide range of nets models. We treat in detail place/transition nets and important extensions of the basic model by individual tokens, test arcs, and time. Based on the idea that Petri nets are monoids suggested by Meseguer and Montanari we define a rewriting semantics that maps place/transition nets into rewriting logic specifications. We furthermore generalize this result to a general form of algebraic net specifications subsuming also colored nets as a special case. The soundness and completeness results we state relate the commutative process semantics of nets proposed by Best and Devillers to the model-theoretic semantics of rewriting logic in the sense of natural isomorphisms between suitable functors. In addition we show how place/transition nets with test arcs and timed nets can be equipped with a rewriting semantics and discuss how other extensions can be treated along similar lines. Beyond the conceptual unification of quite different kinds of nets within a single framework, the rewriting semantics can provide a guide for future extensions of nets and help to cope with the growing diversity of models in this field. On the practical side, a major application of the rewriting semantics is its use as a logical and operational representation of net models for formal verification and for the efficient execution and analysis using a rewriting engine such as Maude, which also allows us to specify different execution and analysis strategies in the same rewriting logic language by means of reflection.

Usually, the maximally permissive control of Petri nets with an OR-logic constraint is difficult to implement. In this paper, OR-logic is easily enforced using a colored Petri net. A colored Petri net place, named colored monitor place, is designed to monitor the states of constraints. A so-called guard function of colored Petri nets that maps certain transitions into a Boolean expression is suitably defined on the colored sets. The maximally permissive control is then obtained via the guard function. In addition, a constraint transformation method for marked graphs with uncontrollable transitions is proposed.