Showing papers on "Petri net published in 2004"

Workflow mining: discovering process models from event logs

Abstract: 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 also demonstrate that it is not possible to discover arbitrary workflow processes. We explore a class of workflow processes that can be discovered. We show that the /spl alpha/-algorithm can successfully mine any workflow represented by a so-called SWF-net.

Discrete, continuous, and hybrid Petri Nets

Abstract: Petri Nets were introduced and still successfully used to analyze and model discrete event systems especially in engineering and computer sciences such as in automatic control. Recently this discrete Petri Nets formalism was successfully extended to continuous and hybrid systems. This monograph presents a well written and clearly organized introduction in the standard methods of Petri Nets with the aim to reach an accurate understanding of continuous and hybrid Petri Nets, while preserving the consistency of basic concepts throughout the book. The book is a monograph as well as a didactic tool which is easy to understand due to many simple solved examples and detailed figures. In its second completely reworked edition various sections, concepts and recently developed algorithms are added as well as additional examples/exercises.

Elementary siphons of Petri nets and their application to deadlock prevention in flexible manufacturing systems

Abstract: A variety of important Petri net-based methods to prevent deadlocks arising in flexible manufacturing systems (FMS) are to add some control places and related arcs to strict minimal siphons (SMS) such that no siphon can be emptied. Since the number of minimal siphons grows in general exponentially with respect to a Petri net size, their disadvantages lie in that they often add too many additional places to the net, thereby making the resulting net model much more complex than the original one. This paper explores ways to minimize the new additions of places while achieving the same control purpose. It proposes for the first time the concept of elementary siphons that are a special class of siphons. The set of elementary siphons in a Petri net is generally a proper subset of the set of all SMS. Its smaller cardinality becomes evident in large Petri net models. This paper proves that by adding a control place for each elementary siphon to make sure that it is marked, deadlock can be successfully prevented. Compared with the existing methods, the new method requires a much smaller number of control places and, therefore, is suitable for large-scale Petri nets. An FMS example is used to illustrate the proposed concepts and policy, and show the significant advantage over the previous methods.

Timed automata: Semantics, algorithms and tools

Abstract: This chapter is to provide a tutorial and pointers to results and related work on timed automata with a focus on semantical and algorithmic aspects of verification tools. We present the concrete and abstract semantics of timed automata (based on transition rules, regions and zones), decision problems, and algorithms for verification. A detailed description on DBM (Difference Bound Matrices) is included, which is the central data structure behind several verification tools for timed systems. As an example, we give a brief introduction to the tool UPPAAL.

The tool TINA – Construction of abstract state spaces for petri nets and time petri nets

Abstract: In addition to the graphic-editing facilities, the software tool Tina proposes the construction of a number of representations for the behaviour of Petri nets or Time Petri nets. Various techniques are used to extract views of the behaviour of nets, preserving certain classes of properties of their state spaces. For Petri nets, these abstractions help prevent combinatorial explosion, relying on so-called partial order techniques such as covering steps and/or persistent sets. For Time Petri nets, which have, in general, infinite state spaces, they provide a finite symbolic representation of their behaviour in terms of state classes.

Deadlock control methods in automated manufacturing systems

Abstract: As more and more producers move to use flexible and agile manufacturing as a way to keep them with a competitive edge, the investigations on deadlock resolution in automated manufacturing have received significant attention for a decade. Deadlock and related blocking phenomena often lead to catastrophic results in automated manufacturing systems. Their efficient handling becomes a necessary condition for a system to gain high productivity. This paper intends to present a tutorial survey of state-of-the art modeling and deadlock control methods for discrete manufacturing systems. It presents the updated results in the areas of deadlock prevention, detection and recovery, and avoidance. It focuses on three modeling methods: digraphs, automata, and Petri nets. Moreover, for each approach, the main and relevant contributions are selected enlightening pros and cons. The paper concludes with the future research needs in this important area in order to bridge the gap between the academic research and industrial needs.

Lectures on Concurrency and Petri Nets

Abstract: Over the last decade there has been a shift from “data-aware” information systems to “process-aware” information systems. To support business processes an enterprise information system needs to be aware of these processes and their organizational context. Business Process Management (BPM) includes methods, techniques, and tools to support the design, enactment, management, and analysis of such operational business processes. BPM can be considered as an extension of classical Workflow Management (WFM) systems and approaches. This tutorial introduces models, systems, and standards for the design, analysis, and enactment of workflow processes. Petri nets are used for the modeling and analysis of workflows. Using Petri nets as a formal basis, contemporary systems, languages, and standards for BPM and WFM are discussed. Although it is clear that Petri nets can serve as a solid foundation for BPM/WFM technology, in reality systems, languages, and standards are developed in an ad-hoc fashion. To illustrate this XPDL, the “Lingua Franca” proposed by the Workflow Management Coalition (WfMC), is analyzed using a set of 20 basic workflow patterns. This analysis exposes some of the typical semantic problems restricting the application of BPM/WFM technology.

Service-oriented Design : A Multi-viewpoint Approach

Abstract: As the technology associated to the ?Web Services? trend gains significant adoption, the need for a corresponding design approach becomes increasingly important. This paper introduces a foundational model for designing (composite) services. The innovation of this model lies in the identification of four interrelated viewpoints (interface behaviour, provider behaviour, choreography, and orchestration) and their formalization from a control-flow perspective in terms of Petri nets. By formally capturing the interrelationships between these viewpoints, the proposal enables the static verification of the consistency of composite services designed in a cooperative and incremental manner. A proof-of-concept simulation and verification tool has been developed to test the possibilities of the proposed model.

Workflow Management: Models, Methods, and Systems

Abstract: This book offers a comprehensive introduction to workflow management, the management of business processes with information technology. By defining, analyzing, and redesigning an organization's resources and operations, workflow management systems ensure that the right information reaches the right person or computer application at the right time. The book provides a basic overview of workflow terminology and organization, as well as detailed coverage of workflow modeling with Petri nets. Because Petri nets make definitions easier to understand for nonexperts, they facilitate communication between designers and users. The book includes a chapter of case studies, review exercises, and a glossary. A special Web site developed by the authors, www.workflowcourse.com, features animation, interactive examples, lecture materials, exercises and solutions, relevant links, and other valuable resources for the classroom.

Fault diagnosis of electric power systems based on fuzzy Petri nets

Abstract: In this paper, Fuzzy Petri Nets (FPN) is used as a modeling tool to build fault diagnosis models aimed to accurately diagnose faults when some incomplete and uncertain alarm information of protective relays and circuit breakers is detected. In order to understand the significance of fault diagnosis models more conveniently, the definition and structure of FPNs are necessarily introduced at first. Then, models of fault diagnosis based on FPN are built, and their corresponding logical testifications are carried out. Finally, the validity and feasibility of this method is illustrated by simulation examples. It is shown from seven cases that the faulted system elements can be diagnosed correctly by use of these models, and a satisfying result can also be achieved even in the situation with large amount of incomplete and uncertain alarm information.

Design and Implementation of the YAWL System

Abstract: This paper describes the implementation of a system supporting YAWL (Yet Another Workflow Language). YAWL is based on a rigorous analysis of existing workflow management systems and related standards using a comprehensive set of workflow patterns. This analysis shows that contemporary workflow systems, relevant standards (e.g. XPDL, BPML, BPEL4WS), and theoretical models such as Petri nets have problems supporting essential patterns. This inspired the development of YAWL by taking Petri nets as a starting point and introducing mechanisms that provide direct support for the workflow patterns identified. As a proof of concept we have developed a workflow management system supporting YAWL. In this paper, we present the architecture and functionality of the system and zoom into the control-flow, data, and operational perspectives.

Service-oriented Design: A Multi-viewpoint Approach

Abstract: As the technology associated with the "Web Services" trend gains significant adoption, the need for a corresponding design approach becomes increasingly important. This paper introduces a foundational model for designing (composite) services. The innovation of this model lies in the identification of four interrelated viewpoints (interface behaviour, provider behaviour, choreography, and orchestration) and their formalization from a control-flow perspective in terms of Petri nets. By formally capturing the interrelationships between these viewpoints, the proposal enables the static verification of the consistency of composite services designed in a cooperative and incremental manner. A proof-of-concept simulation and verification tool has been developed to test the possibilities of the proposed model.

Urban traffic control structure based on hybrid Petri nets

Abstract: An urban network of signalized intersections can be suitably modeled as a hybrid system, in which the vehicle flow behavior is described by means of a time-driven model and the traffic light dynamics are represented by a discrete event model. In this paper, a model of such a network via hybrid Petri nets is used to state and solve the problem of coordinating several traffic lights with the aim of improving the performance of some classes of special vehicles, i.e., public and emergency vehicles. The proposed model has been validated using real traffic data relevant to the city of Torino, Italy. Some relevant experimental results are reported and discussed.

Performance modeling and analysis of workflow

Abstract: Workflow model analysis is performed at logic, temporal, and performance levels. This paper mainly deals with the performance level issues. Workflow net (WF-net) is extended with time information to the timing workflow net (TWF-net). To provide a formal framework for modeling and analyzing workflow, this paper proposes a multidimension workflow net (MWF-net) that include multiple TWF-nets and the organization and resource information. The algorithm to decompose a free-choice and acyclic Petri nets (PN) into a set of T-components is extended to a TWF-net containing iteration structures. Then, resource availability and workload analysis is performed. A method for computing the lower bound of average turnaround time of transaction instances processed in a MWF-net is proposed. Finally a case study is used to show that the proposed method can be effectively utilized in practice.

Modeling and simulation of molecular biology systems using petri nets: modeling goals of various approaches

Abstract: Petri nets are a discrete event simulation approach developed for system representation, in particular for their concurrency and synchronization properties. Various extensions to the original theory of Petri nets have been used for modeling molecular biology systems and metabolic networks. These extensions are stochastic, colored, hybrid and functional. This paper carries out an initial review of the various modeling approaches based on Petri net found in the literature, and of the biological systems that have been successfully modeled with these approaches. Moreover, the modeling goals and possibilities of qualitative analysis and system simulation of each approach are discussed.

Opacity Generalised to Transition Systems

Abstract: Recently, opacity has proved a promising technique for describing security properties. Much of the work has been couched in terms of Petri nets. Here, we extend the notion of opacity to the model of labelled transition systems and generalise opacity in order to better represent concepts from the literature on information flow. In particular, we establish links between opacity and the information flow concepts of anonymity and non-inference. We also investigate ways of verifying opacity when working with Petri nets. Our work is illustrated by two examples, one describing anonymity in a commercial context, and the other modelling requirements upon a simple voting system.

The use of the Petri net reduction approach for an optimal deadlock prevention policy for flexible manufacturing systems

Abstract: In a flexible manufacturing system (FMS) with multiple products, deadlocks can arise due to limited shared resources, such as machines, robots, buffers, fixtures etc. The development of efficient deadlock prevention policies, which can optimise the use of system resources, while preventing deadlocks from occurring, has long been an important issue to be addressed. In [1], an optimal deadlock prevention policy was proposed, based on the use of reachability graph (RG) analysis of the Petri net model (PNM) of a given FMS and the synthesis of a set of new net elements, namely places with initial marking and related arcs, to be added to the PNM, using the theory of regions. The policy proposed in [1] is optimal in the sense that it allows the maximal use of resources in the system according to the production requirements. For very big PNMs, the reachability graph of the PNMs becomes very large and the necessary computations to obtain an optimal deadlock prevention policy become more difficult. In this paper, we propose the use of the Petri net reduction approach to simplify very big PNMs so as to make necessary calculations easily in order to obtain an optimal deadlock prevention policy for FMSs. An example is provided for illustration.

Model validation of biological pathways using Petri nets--demonstrated for apoptosis.

Abstract: This paper demonstrates the first steps of a new integrating methodology to develop and analyse models of biological pathways in a systematic manner using well established Petri net technologies. The whole approach comprises step-wise modelling, animation, model validation as well as qualitative and quantitative analysis for behaviour prediction. In this paper, the first phase is addressed how to develop and validate a qualitative model, which might be extended afterwards to a quantitative model. The example used in this paper is devoted to apoptosis, the genetically programmed cell death. Apoptosis is an essential part of normal physiology for most metazoan species. Disturbances in the apoptotic process could lead to several diseases. The signal transduction pathway of apoptosis includes highly complex mechanisms to control and execute programmed cell death. This paper explains how to model and validate this pathway using qualitative Petri nets. The results provide a mathematically unique and valid model enabling the confirmation of known properties as well as new insights in this pathway.

Modeling traffic signal control using Petri nets

Abstract: 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.

An extensible editor and simulation engine for Petri nets: RENEW

Abstract: Renew is a computer tool that supports the development and execution of object-oriented Petri nets, which include net instances, synchronous channels, and seamless Java integration for easy modelling. Renew is available free of charge including the Java source code. Due to the growing application area more and more requirements had to be fulfilled by the tool set. Therefore, the architecture of the tool has been refactored to gain more flexibility. Now new features allow for plug-ins on the level of concepts (net formalisms) and on the level of applications (e.g. workflow or agents).

Representation and Recognition of Events in Surveillance Video Using Petri Nets

Abstract: Detection of events is an essential task in surveillance applications. This task requires finding a general event representation method and developing efficient recognition algorithms dealing with this representation. In this paper, we describe an interactive system for querying surveillance video about events. The queries may not be known in advance and have to be composed from primitive events and previously defined queries. We propose using Petri nets as both representation and recognition methods. The Petri net representation for users' queries is derived automatically from simpler event nets. Recognition is then performed by tokens moving through the Petri nets.

Modelling Opacity using Petri Nets

Abstract: We consider opacity as a property of the local states of the secure (or high-level) part of the system, based on the observation of the local states of a low-level part of the system as well as actions. We propose a Petri net modelling technique which allows one to specify different information flow properties, using suitably defined observations of system behaviour. We then discuss expressiveness of the resulting framework and the decidability of the associated verification problems.

Modeling and deadlock control of automated guided vehicle systems

Abstract: This paper presents a colored resource-oriented Petri net (CROPN) modeling method to deal with conflict and deadlock arising in automated guided vehicles (AGV) systems. It can handle both bidirectional and unidirectional paths. The former offer additional flexibility, efficiency, and cost saving when compared with the latter. Yet, they exhibit more challenging AGV management problems. Unlike jobs that can enter and leave automated manufacturing systems, AGVs always stay in the system. By modeling nodes with places and lanes with transitions, the proposed method can construct CROPN models for changing AGV routes. A control policy suitable for real-time implementation is presented.

Deadlock Resolution in Computer-Integrated Systems

Abstract: LIST OF CONTRIBUTORS PREFACE INTRODUCTION TO DEADLOCK RESEARCH IN COMPUTER-INTEGRATED SYSTEMS M.P. Fanti and M.C. Zhou DEADLOCK AVOIDANCE IN AUTOMATED MANUFACTURING SYSTEMS USING FINITE AUTOMATA AND STATE SPACE SEARCH A. Yalcin, T. Tai, and T.O. Boucher SYNTHESIS OF DEADLOCK-FREE SUPERVISORY CONTROLLERS USING AUTOMATA A. Ramirez-Serrano and B. Benhabib DEADLOCK AVOIDANCE AND DYNAMIC ROUTING FLEXIBILITY IN AUTOMATED MANUFACTURING SYSTEMS M. Lawley DIGRAPH-BASED TECHNIQUES FOR DEADLOCK RESOLUTION IN AUTOMATED MANUFACTURING SYSTEMS M.P. Fanti, B. Maione, G. Maione, and B. Turchiano DEADLOCK-FREE SUPERVISORY CONTROL FOR ASSEMBLY AND DISASSEMBLY SYSTEMS E. Roszkowska DEADLOCK AVOIDANCE ALGORITHMS AND IMPLEMENTATION: A MATRIX-BASED APPROACH J. Mireles Jr., F. Lewis, A. Gurel, and S. Bogdan DEADLOCK DETECTION AND PREVENTION OF AUTOMATED MANUFACTURING SYSTEMS USING PETRI NETS AND SIPHONS M.D. Jeng, and X. Xie SIPHON-BASED CHARACTERIZATION OF LIVENESS AND LIVENESS-ENFORCING SUPERVISION FOR SEQUENTIAL RESOURCE ALLOCATION SYSTEMS S. Reveliotis ELEMENTARY SIPHONS OF PETRI NETS FOR EFFICIENT DEADLOCK CONTROL Z. Li and M.C. Zhou RESOURCE-ORIENTED PETRI NETS IN DEADLOCK PREVENTION AND AVOIDANCE N. Wu and M.C. Zhou THE EFFECT OF MODELING AND CONTROL TECHNIQUES ON THE MANAGEMENT OF DEADLOCKS IN FMS L. Ferrarini and L. Piroddi DEADLOCK CHARACTERIZATION AND RESOLUTION IN INTERCONNECTION NETWORKS T. M. Pinkston DEADLOCK MODELS FOR A MULTI-SERVICE MEDIUM ACCESS PROTOCOL EMPLOYING A SLOTTED ALOHA OR Q-ARY TREE BASED SIGNALING CHANNEL M.V. Ivanovich DEADLOCK-FREE TCP OVER HIGH-SPEED INTERNET R.K.C. Chang, H.Y. Chan and A.W. Yeung DEADLOCK RESOLUTION IN LARGE-SCALE INTERNET COMPUTING J. Park MODELS USED IN STATIC ANALYSIS FOR DEADLOCKS OF ADA TASKING PROGRAMS M. Tiusanen and T. Murata DEADLOCK HANDLING IN DATABASE SYSTEMS M. Weske INDEX

Timed state space analysis of real-time preemptive systems

Abstract: A modeling notation is introduced which extends time Petri nets with an additional mechanism of resource assignment making the progress of timed transitions be dependent on the availability of a set of preemptable resources The resulting notation, which we call preemptive time Petri nets, permits natural description of complex real-time systems running under preemptive scheduling, with periodic, sporadic, and one-shot processes, with nondeterministic execution times, with semaphore synchronizations and precedence relations deriving from internal task sequentialization and from interprocess communication, running on multiple processors A state space analysis technique is presented which supports the validation of preemptive time Petri net models, combining tight schedulability analysis with exhaustive verification of the correctness of logical sequencing The analysis technique partitions the state space in equivalence classes in which timing constraints are represented in the form of difference bounds matrixes This permits it to maintain a polynomial complexity in the representation and derivation of state classes, but it does not tightly encompass the constraints deriving from preemptive behavior, thus producing an enlarged representation of the state space False behaviors deriving from the approximation can be cleaned-up through an algorithm which provides a necessary and sufficient condition for the feasibility of a behavior along with a tight estimation of its timing profile

Semantics of Control-Flow in UML 2.0 Activities

Abstract: The recent major revision of the UML has introduced significant changes and additions. In particular, the metamodel portion underlying Activity Diagrams has been completely reengineered, with Activity being the central concept, the successor of ActivityGraph in UML 1.5. A denotational and compositional semantics for Activities is defined as a mapping from Activities into procedural Petri nets. The semantics excludes data type annotations and all features based on them, but includes all kinds of control flow, including non well-formed concurrency and, particularly, procedure calling

Intelligent decision making in disassembly process based on fuzzy reasoning Petri nets

Abstract: Practical disassembly process planning is extremely important for efficient material recycling and components reuse. The research work for the process planning in literature focuses on the generation of optimal sequences based on the predictive information of products. The used products, unfortunately, exhibit high uncertainty since products may experience very different conditions during their use stage. The indeterminate characteristics associated to used products often makes the predetermined plan unrealistic. Their disassembly process has to be decided dynamically adaptive to the products' specific status. To be able to deal with uncertainty in a dynamic decision making process, this paper presents a fuzzy reasoning Petri net (FRPN) model to represent related decision making rules in disassembly process. Using the proposed fuzzy reasoning algorithm based on the FRPN model, the multicriterion disassembly rules can be considered in the parallel way to make the decision automatically and quickly. Instead of producing the disassembly sequences before disassembling a whole product, the proposed method makes intelligent decisions based on dynamically updated status of components in the product at each disassembly step. Therefore, it is adaptive to the changes that arise during the process. Finally, an example is used to illustrate the application of the proposed methodology.

Ladder diagram and Petri-net-based discrete-event control design methods

Abstract: Ladder diagrams (LDs) for a programmable logic controller are a dominant method in discrete event control of industrial automated systems. Yet, the ever-increasing functionality and complexity of these systems have challenged the use of LDs to design their discrete-event controllers. Researchers are constantly pursuing integrated tools that eliminate the limitations of LDs. These tools are aimed not only for control but also system analysis, evaluation, and simulation. For the past several decades, Petri nets (PNs) have emerged as an important tool to provide an integrated solution for modeling, analysis, simulation, and control of industrial automated systems. Different types of PN-based controllers are proposed and intended to apply in the industry. There is a need for more benchmark studies of PN and LD methods in order to form a structured and integrated framework for logic control software development. This paper, for the first time, presents a comprehensive survey on the recent methods for discrete event control design.