Showing papers on "Process architecture published in 1998"

The application of Petri-nets to workflow management

Abstract: Workflow management promises a new solution to an age-old problem: controlling, monitoring, optimizing and supporting business processes. What is new about workflow management is the explicit representation of the business process logic which allows for computerized support. This paper discusses the use of Petri nets in the context of workflow management. Petri nets are an established tool for modeling and analyzing processes. On the one hand, Petri nets can be used as a design language for the specification of complex workflows. On the other hand, Petri net theory provides for powerful analysis techniques which can be used to verify the correctness of workflow procedures. This paper introduces workflow management as an application domain for Petri nets, presents state-of-the-art results with respect to the verification of workflows, and highlights some Petri-net-based workflow tools.

Continuous and hybrid Petri nets

Abstract: Petri nets are widely used to model discrete event dynamic systems (computer systems, manufacturing systems, communication systems…). When a PN contains a large number of tokens, the number of reachable states explodes. This is a practical limitation to the use of Petri nets. Continuous models may provide very good approximations for discrete event systems: this is the basic idea leading to the definition of continuous Petri nets. A continuous PN is a model in which the marking of each place is a real number. In a timed continuous PN, a firing speed is associated with each transition (this basic model is unique although the firing speed may be defined in several ways). Various timed continuous PN models have been defined and they correspond to a specific calculation of the firing speeds. They provide good approximations for performance evaluation when a PN contains a large number of tokens. Modeling a number of parts in a buffer by a real number may generally be an acceptable approximation. However, the s...

Supervisory Control of Discrete Event Systems Using Petri Nets

Abstract: From the Publisher: Supervisory Control of Discrete Event Systems Using Petri Nets presents a novel approach for the supervisory control of discrete event systems using Petri nets. The concepts of supervisory control and discrete event systems are explained, and the background material on general Petri net theory necessary for using the book's control techniques is provided. A large number of examples are used to illustrate the concepts and techniques presented in the text, and there are plenty of references for those interested in additional study or more information on a particular topic. Supervisory Control of Discrete Event Systems Using Petri Nets is intended for graduate students, advanced undergraduates, and practicing engineers who are interested in the control problems of manufacturing, communication and computer networks, chemical process plants, and other high level control applications.

Petri Nets as Token Objects: An Introduction to Elementary Object Nets

Abstract: The model of Elementary Object System is introduced and motivated by several examples and applications. Object systems support a modeling of systems by Petri nets following the paradigm of Object-Oriented Modeling. They are composed of a System Net and one or more Object Nets which can be seen as token objects of the system net. By this approach an interesting and challenging two-level system modeling technique is introduced. Similar to the object-oriented approach, complex systems are modeled close to their real appearance in a natural way to promote clear and reliable concepts. Applications in fields like workflow, flexible manufacturing or agent-oriented approaches (mobile agents and/or intelligent agents as in AI research) are feasible. This paper gives an introduction with several examples, but only few definitions and no theorems, which can be found, however, in a more elaborated paper.

Modeling, analysis, simulation, scheduling, and control of semiconductor manufacturing systems: A Petri net approach

Abstract: This paper presents a Petri net approach to modeling, analysis, simulation, scheduling, and control of semiconductor manufacturing systems. These systems can be characterized as discrete event systems that exhibit sequential, concurrent, and conflicting relations among the events and operations. Their evolution is dynamic over time. The system complexity is tremendous owing to the complex semiconductor manufacturing processes and test procedures. A formal approach such as Petri nets enables one to describe such complex discrete event systems precisely and thus allows one to perform both qualitative and quantitative analysis, scheduling and discrete-event control of them. This paper also serves as a tutorial paper. It briefly reviews applications of Petri nets in semiconductor manufacturing automation. It then introduces definitions and concepts of Petri nets. It proceeds with a discussion of basic Petri net modules in system modeling, a modeling method and a practical system's modeling example. Next, the paper presents their properties and their implications in manufacturing systems, as well as their analysis methods. Timed Petri nets are introduced for system simulation, performance evaluation, and scheduling purposes. An application-oriented case study is presented. Finally, the paper concludes with the active research areas in applying Petri nets to design of semiconductor manufacturing systems.

Place/transition Petri nets

Abstract: This contributions provides an introduction to the theory of place/transition Petri nets. Topics include the sequential and the concurrent behavior of place/transition Petri nets, marking graphs and coverability trees, and some analysis techniques that are based on the structure of place/transition Petri nets.

Performance Modelling with Deterministic and Stochastic Petri Nets

Abstract: From the Publisher: This text provides an up-to-date treatment of the fundamental techniques and algorithms for numerical analysis of deterministic and stochastic Petri nets, a particular stochastic modelling formalism, and the application of this modelling formalism to performance analysis for parallel computer architectures.

Excellence By Design: Transforming Workplace and Work Practice

Abstract: Workplace-Making Beyond the Stable State. Concepts of Process Architecture. From Stereotype to Dynamic Coherence. The Design Game. The Practice and Tools of Process Architecture. A Synthesis of Ideas and Practices: The LX Workplace Experiment. Process Architecture Revisited. Learning Process Architecture. Epilogue. Notes. Index.

In terms of nets : system design with Petri nets and process algebra

Abstract: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.

Fault Detection and Diagnosis in Distributed Systems: An Approach by Partially Stochastic Petri Nets

Abstract: We address the problem of alarm correlation in large distributed systems. The key idea is to make use of the concurrence of events in order to separate and simplify the state estimation in a faulty system. Petri nets and their causality semantics are used to model concurrency. Special partially stochastic Petri nets are developed, that establish some kind of equivalence between concurrence and independence. The diagnosis problem is defined as the computation of the most likely history of the net given a sequence of observed alarms. Solutions are provided in four contexts, with a gradual complexity on the structure of observations.

Differential Petri nets: representing continuous systems in a discrete-event world

Abstract: Differential Petri nets are a new extension of Petri nets. Through the introduction of the differential place, the differential transition, and suitable evolution rules, it is possible to model concurrently discrete-event processes and continuous-time dynamic processes, represented by systems of linear ordinary differential equations. This model can contribute to the performance analysis and design of industrial supervisory control systems and of hybrid control systems in general.

Recent developments in non-markovian stochastic petri nets

Abstract: Analytical modeling plays a crucial role in the analysis and design of computer systems. Stochastic Petri Nets represent a powerful paradigm, widely used for such modeling in the context of dependability, performance and performability. Many structural and stochastic extensions have been proposed in recent years to increase their modeling power, or their capability to handle large systems. This paper reviews recent developments by providing the theoretical background and the possible areas of application. Markovian Petri Nets are first considered together with very well established extensions known as Generalized Stochastic Petri Nets and Stochastic Reward Nets. Key ideas for coping with large state spaces are then discussed. The challenging area of non-Markovian Petri nets is considered, and the related analysis techniques are surveyed together with the detailed elaboration of an example. Finally new models based on Continuous or Fluid Stochastic Petri Nets are briefly discussed.

Workflow management based on process model repositories

Abstract: Workflow management is an area of increasing interest. Nonetheless there are only a few workflow systems which are actually used for supporting business processes in an industrial context. Most of these systems only deal with processes which create and manipulate unstructured pieces of information, like documents and images. Our workflow management approach, called the FUNSOFT net approach, additionally supports the management of structured pieces of information, called objects. In doing so, we use a repository which is used to store information about process models and about individual processes. This repository is particularly useful for processes dealing with highly structured information, such as software processes. We describe the experience in using such a repository. We point out which of these experiences may be useful for developers of other workflow management systems as well.

Modeling Petri Nets as Local Constraint Equations for Hybrid Systems Using Modelica

Abstract: To model complex mixed continuous/discrete, hybrid, systems, the continuous part can be described by differential and algebraic equations using an object-oriented modeling language such as Modelica. It is shown how a discrete formalism such as Petri nets can be incorporated by describing all components by strictly local equations. This allows a unifying treatment since both the continuous and the discrete part of a system are described by equations. The resulting Petri net library is applied to model the redundancy management control of the elevator subsystem of an aircraft.

Web-based enterprise management architecture

Abstract: This article is a description of the Web-Based Enterprise Management initiative. It discusses both the substance of the initiative itself, in the form of the overall architectural approach implied by WBEM, and the industry context that gave rise to WBEM. The industry context is the current state of management systems and software, standardization efforts, and the actual systems being managed. These provided the major influences in shaping the evolution of the WBEM initiative. The substance of the initiative is provided by the WBEM process and information architectures that support a scalable and heterogeneous management structure. The various aspects of the process architecture are covered, including the object manager, object providers, schema management, and protocols required for communication among the various components of the architecture. An overview of the information architecture is provided in the form of a summary of the Desktop Management Taskforce's Common Information Model schema implemented by WBEM.

Use of Petri nets for resource allocation in projects

Abstract: Traditional models for project management have not adequately incorporated a number of factors that are important for resource allocation. This paper describes the use of Petri nets to facilitate resource allocation in projects under some conditions commonly encountered in practice. Petri nets provide a powerful formalism for representing and analyzing concurrent systems. To date, however, very little has been done to integrate this graphical and mathematical tool with the area of project management. Petri net models can be used to analyze interdependencies, criticality, substitution, conflicting resource priorities and variations in the availability of resources. This paper proposes a new model and demonstrates the usefulness of the model for real-time activity scheduling in a resource-constrained project environment. The model has been computerized using the C language, and a simple project is chosen as an example to provide step-by-step explanations of the simulation carried out. This paper also discusses the implications of the model and the analysis it supports.

ESTL: A Temporal Logic for Events and States

Abstract: In some phases of system development state-based methods are adequate; in others event-based methods are adequate. Petri nets provide a system model which supports both methods and thus allow a smooth transition between the different phases of system development. Most temporal logics for Petri nets, however, do not support both methods. In this paper we introduce a temporal logic for Petri nets which allows to argue about states as well as to argue about events. This way, specifications in the early phases can be event-based and verification in later phases can be state-based within a single formalism.

Timed Petri Nets in Hybrid Systems: Stability and SupervisoryControl

Abstract: In this paper, timed Petri nets are used to model and control hybrid systems. Petri nets are used instead of finite automata primarily because of the advantages they offer in dealing with concurrency and complexity issues. A brief overview of existing results on hybrid systems that are based on Petri nets is first presented. A class of timed Petri nets named programmable timed Petri nets (PTPN) is then used to model hybrid systems. Using the PTPN, the stability and supervisory control of hybrid systems are addressed and efficient algorithms are introduced. In particular, we present sufficient conditions for the uniform ultimate boundness of hybrid systems composed of multiple linear time invariant plants which are switched between using a logical rule described by a Petri net. This paper also examines the supervisory control of a hybrid system in which the continuous state is transfered to a region of the state space in a way that respects safety specifications on the plant‘s discrete and continuous dynamics.

Petri nets in performance analysis : An introduction

Abstract: In this tutorial paper, the authors discuss the motivations that led to the adoption of Petri nets for performance evaluation, define the class of Petri nets that is most frequently used for performance analysis, and present the subclasses that allow a simpler derivation of performance metrics. Definitions and discussions are paralleled with examples, thus visualizing the strong and weak points of the different alternatives.

Petri Nets and Digital Hardware Design

Abstract: Petri nets are a powerful language for describing processes in digital hardware, and particularly asynchronous or self-timed circuits. Self-timed circuits are designed to operate without the use of a global clock signal. Applications for such circuits are likely to increase during the next decade, due to problems with on-chip event coordination as VLSI technology approaches a density of one hundred million transistors per chip. Designing such circuits without help of formal tools does not seem to be possible. We present an overview of the methods for specification, verification and synthesis of asynchronous circuits with the aid of Petri nets. We present a number of design examples which are used to illustrate the authors' belief that Petri nets could become widely accepted by digital system designers as a design method.

Creating executable models of influence nets with colored Petri nets

Abstract: This paper describes a methodology for converting an influence net to a dynamic executable model, implemented using the colored Petri net (CPN) formalism and tools, so that it can be used to assess the impact of a set of controllable events or actions on outcomes of interest; specifically, assess the impact of various sequences and timing of those actionable events With this methodology, alternative courses of action, first defined using influence nets, which are static equilibrium models, can be refined by adding sequence and timing information for analysis and comparison The techniques developed offer a means to integrate intelligence and operational planning models to improve course of action development The paper includes a description of the automated algorithms that convert an influence net to a colored Petri net and illustrates how that model can be used for the analysis of alternative courses of action

Modeling and simulation of an electronic component manufacturing system using hybrid Petri nets

Abstract: Modelling and analysis for the design and operation of manufacturing systems is a vital need. For semiconductor manufacturing systems, which are large scale systems, discrete Petri nets do not constitute an adequate tool for modeling and analysis. In fact, use of discrete Petri nets is confronted with tile state explosion and the high cost of simulation. In this paper, hybrid Petri nets are presented as powerful tools for modeling and simulation of semiconductor manufacturing systems. This model has been used for modeling and simulation of a real life electronic components manufacturing system. It provides an accurate and first simulation of this system.

Net structure and control logic synthesis of controlled Petri nets

Abstract: Control logic synthesis of discrete-event systems is considered in the setting of controlled Petri nets. The problem is to find a control policy that restricts the behavior of a controlled Petri net so that a collection of forbidden state conditions is satisfied. S-decreases are introduced as a tool for the control synthesis. The S-decreases are weight vectors defined on the places of a net such that the weighted sum of tokens in the net never increases with any transition firing. On the basis of S-decreases, the authors propose an efficient method for the synthesis of the maximally permissive state feedback control polity for a class of controlled Petri nets whose uncontrolled subnets are forward and backward conflict-free nets. This method upgrades all integer linear programming-based methods for which one only requires to solve the much simpler linear programming problems to determine maximally permissive controls.

Lectures on Petri nets : advances in Petri nets

Abstract: Petri nets, process algebras and concurrent programming languages.- Petri nets and production systems.- Computer Supported Cooperative Work and Petri Nets.- Petri nets and digital hardware design.- An introduction to the practical use of coloured Petri Nets.- Protocol specification using P-graphs, a technique based on coloured Petri Nets.- Distributed algorithms for networks of agents.- Efficient performance analysis techniques for stochastic well-formed nets and stochastic process algebras.- Modelling and analysis of distributed software using GSPNs.