Dissertations / Theses on the topic 'Petri nets Computer simulation'
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1
Sellami, Hatem. "Parallel simulation of marked graphs." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13045.
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Jones, Robert Linzey III. "Simulation and numerical solution of stochastic Petri nets with discrete and continuous timing." W&M ScholarWorks, 2002. https://scholarworks.wm.edu/etd/1539623410.
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We introduce a novel stochastic Petri net formalism where discrete and continuous phase-type firing delays can appear in the same model. By capturing deterministic and generally random behavior in discrete or continuous time, as appropriate, the formalism affords higher modeling fidelity and efficiencies to use in practice. We formally specify the underlying stochastic process as a general state space Markov chain and show that it is regenerative, thus amenable to renewal theory techniques to obtain steady-state solutions. We present two steady-state analysis methods depending on the class of problem: one using exact numerical techniques, the other using simulation. Although regenerative structures that ease steady-state analysis exist in general, a noteworthy problem class arises when discrete-time transitions are synchronized. In this case, the underlying process is semi-regenerative and we can employ Markov renewal theory to formulate exact and efficient numerical solutions for the stationary distribution. We propose a solution method that shows promise in terms of time and space efficiency. Also noteworthy are the computational tradeoffs when analyzing the "embedded" versus the "subordinate" Markov chains that are hidden within the original process. In the absence of simplifying assumptions, we propose an efficient regenerative simulation method that identifies hidden regenerative structures within continuous state spaces. The new formalism and solution methods are demonstrated with two applications.
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Mabry, Ryan. "Gate Level Dynamic Energy Estimation In Asynchronous Circuits Using Petri Nets." Scholar Commons, 2007. http://scholarcommons.usf.edu/etd/3826.
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This thesis introduces a new methodology for energy estimation in asynchronous circuits. Unlike existing probabilistic methods, this is the first simulative work for energy estimation in all types of asynchronous circuits.
The new simulative methodology is based on Petri net modeling. A real delay model is incorporated to capture both gate delays and interconnect delays. The switching activity at each gate is captured to measure the average dynamic energy consumed per request/acknowledge handshaking pair. The new type of Petri net is called Hierarchical Colored Asynchronous Hardware Petri net (HCAHPN). The HCAHPN is able to capture the temporal and spatial correlations of signals within a circuit, while preserving gate logic behavior and timing information.
While Petri nets have been previously used for simulating combinational and sequential circuits, this is the first work that uses Petri nets for simulating asynchronous circuits. While different asynchronous design styles make various assumptions on the gate and wire delays present with the circuit, the physical implementations of these circuits always have gate and interconnect delays. Unlike previous methods, the proposed methodology is independent of the asynchronous design style used and it can be adapted for all types of asynchronous circuits that use handshaking communication.
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Wang, Yi-ke. "Using an extended object model for object-oriented parallel simulation of VLSI microprocessors /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9823320.
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Habib, Zadeh Esmaeil. "Modelling and Quantitative Analysis of Performance vs Security Trade-offs in Computer Networks: An investigation into the modelling and discrete-event simulation analysis of performance vs security trade-offs in computer networks, based on combined metrics and stochastic activity networks (SANs)." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/17412.
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Performance modelling and evaluation has long been considered of paramount
importance to computer networks from design through development, tuning and
upgrading. These networks, however, have evolved significantly since their first introduction
a few decades ago. The Ubiquitous Web in particular with fast-emerging
unprecedented services has become an integral part of everyday life. However, this
all is coming at the cost of substantially increased security risks. Hence cybercrime is
now a pervasive threat for today’s internet-dependent societies. Given the frequency
and variety of attacks as well as the threat of new, more sophisticated and destructive
future attacks, security has become more prevalent and mounting concern in
the design and management of computer networks. Therefore equally important if
not more so is security.
Unfortunately, there is no one-size-fits-all solution to security challenges. One security
defence system can only help to battle against a certain class of security threats. For overall security, a holistic approach including both reactive and proactive
security measures is commonly suggested. As such, network security may have
to combine multiple layers of defence at the edge and in the network and in its
constituent individual nodes.
Performance and security, however, are inextricably intertwined as security measures
require considerable amounts of computational resources to execute. Moreover, in
the absence of appropriate security measures, frequent security failures are likely
to occur, which may catastrophically affect network performance, not to mention
serious data breaches among many other security related risks.
In this thesis, we study optimisation problems for the trade-offs between performance
and security as they exist between performance and dependability. While
performance metrics are widely studied and well-established, those of security are
rarely defined in a strict mathematical sense. We therefore aim to conceptualise and
formulate security by analogy with dependability so that, like performance, it can
be modelled and quantified.
Having employed a stochastic modelling formalism, we propose a new model for a
single node of a generic computer network that is subject to various security threats.
We believe this nodal model captures both performance and security aspects of a
computer node more realistically, in particular the intertwinements between them.
We adopt a simulation-based modelling approach in order to identify, on the basis
of combined metrics, optimal trade-offs between performance and security and facilitate
more sophisticated trade-off optimisation studies in the field.
We realise that system parameters can be found that optimise these abstract combined
metrics, while they are optimal neither for performance nor for security individually.
Based on the proposed simulation modelling framework, credible numerical
experiments are carried out, indicating the scope for further work extensions for a
systematic performance vs security tuning of computer networks.
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Propes, Nicholas Chung. "Hybrid Systems Diagnosis and Control Reconfiguration for Manufacturing Systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5150.
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A methodology for representing and analyzing manufacturing systems in a hybrid systems framework for control reconfiguration purposes in the presence of defects and failures at the product and system levels is presented. At the top level, a supervisory Petri net directs parts/jobs through the manufacturing system. An object-based hybrid systems model that incorporates both Petri nets at the event-driven level and differential equations at the time-driven level describes the subsystems. Rerouting capabilities utilizing this model at the product and operation levels were explained. Simulations were performed on a testbed model for optimal time and mode transition cost to determine the route for parts. The product level reconfiguration architecture utilizes an adaptive network-based fuzzy inference system (ANFIS) to map histogram comparison metrics to set-point adjustments when product defects were detected. Tests were performed on good and defective plastic parts from a plastic injection molding machine. In addition, a mode identification architecture was described that incorporates both time- and event-driven information to determine the operating mode of a system from measured sensor signals. Simulated data representing the measured process signals from a Navy ship chiller system were used to verify that the appropriate operating modes were detected.
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Soltani-Moghaddam, Alireza. "Network simulator design with extended object model and generalized stochastic petri-net /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9999317.
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Wang, Xiaobo. "Design and Implementation of a Tool for Modeling, Simulation and Verification of Component-based Embedded Systems." Thesis, Linköping University, Department of Computer and Information Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2655.
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Nowadays, embedded systems are becoming more and more complex. For this reason, designers focus more and more to adopt component-based methods for their designs. Consequently, there is an increasing interest on modeling and verification issues of component-based embedded systems.
In this thesis, a tool, which integrates modeling, simulation and verification of component-based embedded systems, is designed and implemented. This tool uses the PRES+, Petri Net based Representation for Embedded Systems, to model component-based embedded systems. Both simulation and verification of systems are based on the PRES+ models.
This tool consists of three integrated sub-tools, each of them with a graphical interface, the PRES+ Modeling tool, the PRES+ Simulation tool and the PRES+ Verification tool. The PRES+ Modeling tool is a graphical editor, with which system designers can model component-based embedded systems easily. The PRES+ Simulation tool, which is used to validate systems, visualizes the execution of a model in an intuitive manner. The PRES+ Verification tool provides a convenient access to a model checker, in which models can be formally verified with respect to temporal logic formulas.
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Kyratzoglou, I. M. (Ioannis M. ). "Computer aided design for Petri Nets." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14669.
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Djemame, Karim. "Distributed simulation of high-level algebraic Petri nets." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301624.
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Cui, Qing Ming. "Parallel and distributed simulation of timed Petri nets." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245946.
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Dahlbom, Anders. "Petri nets for situation recognition." Doctoral thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-13089.
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Situation recognition is a process with the goal of identifying a priori defined situations in a flow of data and information. The purpose is to aid decision makers with focusing on relevant information by filtering out situations of interest. This is an increasingly important and non trivial problem to solve since the amount of information in various decision making situations constantly grow. Situation recognition thus addresses the information gap, i.e. the problem of finding the correct information at the correct time. Interesting situations may also evolve over time and they may consist of multiple participating objects and their actions. This makes the problem even more complex to solve. This thesis explores situation recognition and provides a conceptualization and a definition of the problem, which allow for situations of partial temporal definition to be described. The thesis then focuses on investigating how Petri nets can be used for recognising situations. Existing Petri net based approaches for recognition have some limitations when it comes to fulfilling requirements that can be put on solutions to the situation recognition problem. An extended Petri net based technique that addresses these limitations is therefore introduced. It is shown that this technique can be as efficient as a rule based techniques using the Rete algorithm with extensions for explicitly representing temporal constraints. Such techniques are known to be efficient; hence, the Petri net based technique is efficient too. The thesis also looks at the problem of learning Petri net situation templates using genetic algorithms. Results points towards complex dynamic genome representations as being more suited for learning complex concepts, since these allow for promising solutions to be found more quickly compared with classical bit string based representations. In conclusion, the extended Petri net based technique is argued to offer a viable approach for situation recognition since it: (1) can achieve good recognition performance, (2) is efficient with respect to time, (3) allows for manually constructed situation templates to be improved and (4) can be used with real world data to find real world situations.Anders Dahlbom is also affiliated to Skövde Artificial Intelligence Lab (SAIL), Information Fusion Research Program, Högskolan i Skövde
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English, Sarah L. "Coloured Petri Nets for object-oriented modelling." Thesis, University of Brighton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334740.
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Wiley, Richard Paul. "Performance analysis of Stochastic Timed Petri Nets." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15002.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 305-310.
by Richard Paul Wiley.
Sc.D.
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Bilinski, Krzysztof. "Application of Petri nets in parallel controller design." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336830.
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Usher, Michelle M. "A concurrent visual language based on Petri nets." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366506.
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Fu, Mo. "An analytic model for agent systems with Petri nets." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289933.
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The agent system specification, the agent system implementation and the agent system verification are three essential issues to build an agent system. Many works have been done for the first two issues in recent years. However, as a result of a lack in formal agent modeling techniques, little effort has been made to address the verification issue, which impedes the agent technique a smooth transition from the research lab to the desk of everyday computer engineers. Motivated by this fact and its significance, it is our objective in this dissertation to establish a systematic method for modeling and analysis of agent systems. An approach to combine the agent belief-desire-intention (BDI) theory and the Petri net transducer (PNT) theory is proposed. The resulting belief-planner-actuator model specifies individual behaviors of agents successfully and bridges the gap among belief, desire and intention of agents seamlessly. A set of agent communication protocols is developed to specify the agent social behavior. Theorems on analyzing the Petri Net underlying those protocols are proposed and proved. Based upon the proposed communication protocols, three agent social behavior models are proposed here: direct coordination, meeting-oriented coordination and blackboard-based coordination. To further exploits the power of the agent communication protocols, a framework to model the mobility of agents is proposed. The framework includes a set of stationary agents (SA) and mobile agents (MA). The agent learning ability is modeled based upon the probabilistic Petri net transducer theory. The individual agent learning behavior is then extended to multiple-agent systems, where the game theory and the agent learning model are combined to achieve a number of agent interaction strategies. These strategies include: self-interested learning, complete cooperative learning, bargaining learning and coordinated learning. Several simulation studies have been conducted to investigate the effectiveness of the proposed agent model. This model is further evaluated through its application to the WAVES (web based audio video educational systems) project and the results have indicated that the proposed method is ideal in analysis of agent systems.
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Pilon, Nadine. "Etude et modélisation d'une architecture multi-processeur à hautes performances." Paris 6, 1986. http://www.theses.fr/1986PA066190.
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L'architecture de Civa (calculateurs interconnectés pour l'analyse numérique) et les migrations des données, en particulier des grandes matrices creuses, sont étudiées tout d'abord. Une modélisation en deux volets permet ensuite d'évaluer les performances de Civa: réseau de pétri détaillé pour étudier l'effet des synchronisations et le partage des ressources, et modèle simplifié, à files d'attente, pour les grandes configurations.
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Remy, Pascal A. "On the generation of organizational architectures using Petri nets." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14937.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 185-187.
by Pascal A. Remy.
M.S.
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Pereira, Filipe Gonçalves. "Modeling and simulation of healthcare pharmaceutical environments: a Petri nets approach." Master's thesis, Instituto Politécnico de Bragança, Escola Superior de Tecnologia e Gestão, 2010. http://hdl.handle.net/10198/3421.
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This study examines the drug distribution procedure in hospital, based
on a bibliographic research and an interview with the pharmacy director of
“Hospital de l Rio Ortega” in Vallado lid, Spain. It was necessary to elaborate a
theoretical flux-gram of the medication distribution procedure describing the
various stages in the process, as well as the objectives of the system, and its
critical issues. All these steps depend on various health care providers and
health care assistants directly linked. This systemization allowed the
observance of the critical knots, understood as the processes and elements
with critical impact over the quality of the distribution system. The
understandi ng of the possible causes of the system‟s problems serves here as
the basis for the formulation issues that make the evaluation possible.
There are two basic known types of drug distribution systems:
collective and individual. The collective system is the most primitive,
although there are hospitals worldwide that adopt this system, considered to
be the simplest and lowest in cost of deployment. The individual distribution
system is more complex, it needs more professional pharmacists and a
hospital pharmacy working around the clock and has as main features the fact
that the product or drug is dispensed per patient, and not for the sector in
which one may find himself hospitalized. The research of medication errors
due to the type of distribution system adopted by hospitals has created a
debate on the advantages and disadvantages of the existing systems. The use
of a system model for distribution of medicines will provide a more
appropriate reduction in risk of errors and foremost a reduction in hospital
costs. One objective of this study is to show the best method of distribution of
medicines in a hospital pharmacy, that is, the method of distribution in which
the chance to experience a medication error would be smaller, and
distribution times as well as staff needs were reduced to a minimum.
The main objective of this work is to model the medication distribution
process in Health-care environments, using Petri Net formalism, and extract information from those models through simulation, to support the decision
making relating human resource availability.
This work was done during a stage at the Cartif Foundation in Valladolid
Spain, with the cooperation of the Valladolid University‟s School of Industrial
Engineering. Este estudo examina o procedimento para distribuição de medicamentos
dentro de um hospital, baseado numa pesquisa bibliográfica e uma entrevista
com o director da farmácia do hospital “Hospital del Rio Ortega” em
Valladolid, Espanha. Foi necessário elaborar um fluxogram teórico do
procedimento de distribuição de medicamentos descrevendo os vários passos
do processo, e ainda os objectivos do sistema e os seus pontos críticos. Todos
estes passos dependem de vários assistentes e auxiliares de saúde
directamente ligadas. Esta sistematização permitiu observar os pontos
críticos, compreendido como os elementos com impacto critico na qualidade
do sistema de distribuição. A compreensão das possíveis causas dos problemas
do sistema servem de base para formular questões que tornam possível a sua
avaliação.
Existem dois sistemas básicos de distribuição de medicamentos:
Colectivo e Individual. O sistema colectivo é o tipo de distribuição mais
primitivo, mas apesar disso existem muitos hospitais do mundo que adoptam
este sistema por ser considerado o mais simples e de implementação mais
barata. O sistema individual é mais complexo e necessita de mais profissionais
qualificados, nomeadamente farmacêutico e\ou técnico de farmácia, a
trabalhar 24 horas por dia, tendo como principal característica o facto de que
cada produto ou medicamento é dispensado por pessoa e não por sector ou
andar em que um possa estar hospitalizado. A pesquisa de erros médicos
devido ao tipo de distribuição de medicamentos adoptado pelos hospitais tem
criado debate sobre as vantagens e desvantagens dos sistemas existentes. O
uso de um modelo para a distribuição de medicamentos levará á redução de
erros e acima de tudo pode contribuir para a redução de custos do hospital.
Um dos objectivos deste estudo é mostrar o melhor método de distribuição de
medicamentos de uma farmácia hospitalar, isto é, o método de distribuição
em que se minimiza o risco de erros de medicação, tempos de distribuição
assim como necessidade de recursos humanos. O objectivo principal deste trabalho é modelar o processo de
distribuição de medicamentos em ambiente hospitalar, usando o formalismo
das Redes de Petri, e extrair informação desses modelos através de simulação
para apoiar tomadas de decisão relativas á disponibilidade de recursos
humanos.
Este trabalho foi desenvolvido durante uma estadia na Fundação Cartif
de Valladolid em Espanha com a cooperação da Escola de Engenharias
Industriais da Universidade de Valladolid.
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Karlsson, Daniel. "Verification of Component-based Embedded System Designs." Doctoral thesis, Linköping : Department of Computer and Information Science, Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7473.
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Abou-Loukh, S. J. "Petri nets for computer sequence generation to control batch processes." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355212.
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Ding, Junhua. "An approach for model checking petri nets based software architecture." FIU Digital Commons, 2000. http://digitalcommons.fiu.edu/etd/2821.
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With the inevitable increase in complexity of both hardware and software systems, there is a growing demand for methodologies that can increase confidence in correct system design and construction. Such methodologies will result in improved quality, as well as in a reduction to the total development cost of a system. Our main goal is the development of practical and effective techniques to support for analyzing the behavior of complex systems. More specifically, we focus on model checking method that can be easily introduced into the system development process Software Architecture Methodology (SAM). We chose symbolic model checking method to verify complex software systems, so the verification procedure is automated. In this thesis, our works include: 1. Design a global method for checking SAM software architecture model. 2 Present a compositional model checking method for SAM software architecture methodology. 3. Implement a system to translate SAM model into Symbolic Model Verifier (SMV) model automatically. 4. Prove the correctness of the translation method. Using the compositional model checking method, we check some properties such as reachability and deadlock in a Flexible Manufacturing System (FMS) which is modeled using SAM, and we improve the previous model through the help of the counter example produced from the checking system.
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Bradfield, Julian Charles. "Verifying temporal properties of systems with applications to petri nets." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/6565.
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This thesis provides a powerful general-purpose proof technique for the verification of systems, whether finite or infinite. It extends the idea of finite local model-checking, which was introduced by Stirling and Walker: rather than traversing the entire state space of a model, as is done for model-checking in the sense of Emerson, Clarke et al. (checking whether a (finite) model satisfies a formula), local model-checking asks whether a particular state satisfies a formula, and only explores the nearby states far enough to answer that question. The technique used was a tableau method, constructing a tableau according to the formula and the local structure of the model. This tableau technique is here generalized to the infinite case by considering sets of states, rather than single states; because the logic used, the propositional modal mu-calculus, separates simple modal and boolean connectives from powerful fix-point operators (which make the logic more expressive than many other temporal logics), it is possible to give a relatively straightforward set of rules for constructing a tableau. Much of the subtlety is removed from the tableau itself, and put into a relation on the state space defined by the tableau-the success of the tableau then depends on the well-foundedness of this relation. This development occupies the second and third chapters: the second considers the modal mu-calculus, and explains its power, while the third develops the tableau technique itself The generalized tableau technique is exhibited on Petri nets, and various standard notions from net theory are shown to play a part in the use of the technique on nets-in particular, the invariant calculus has a major role. The requirement for a finite presentation of tableaux for infinite systems raises the question of the expressive power of the mu-calculus. This is studied in some detail, and it is shown that on reasonably powerful models of computation, such as Petri nets, the mu-calculus can express properties that are not merely undecidable, but not even arithmetical. The concluding chapter discusses some of the many questions still to be answered, such as the incorporation of formal reasoning within the tableau system, and the power required of such reasoning.
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Maqbool, Shahbaz. "Transformation of a core scenario model and activity diagrams into Petri nets." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26971.
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For any software development project it is important to capture the requirements in a clear and concise manner. Standardization efforts, such as the development of version 2 of the Unified Modeling Language (UML) by the Object Management Group, and the development of the User Requirements Notation (URN) by the International Telecommunication Union, propose visual languages for capturing requirements in terms of scenario notations. Activity Diagrams and Use Case Maps (UCM) are examples of such scenario languages in UML and in URN, respectively. The developers of these languages have concentrated on the visual notations and only a small amount of effort has been spent in defining precise and formal semantics for these languages.
Core Scenario Model (CSM) is a step towards defining formal semantics to the scenario based languages like UCM, Activity Diagrams and Interaction Diagrams. It includes common scenario information found in the UCM notation and in UML 2.0 Activity Diagrams and Interaction Diagrams, and has been developed as an intermediate language before transformation into formal languages like Petri Nets, Layered Queuing Network etc.
The thesis proposes a transformation method that takes UML Activity Diagrams as input and generates equivalent Petri Nets as output. The transformation approach takes into account the concurrency characteristics of Activity Diagrams.
The thesis also proposes a method for transforming a Core Scenario Model (CSM) representation into equivalent Petri Nets. A Java tool was designed and built for realizing the proposed transformation from CSM to Petri Nets. The application takes as input XML files produced by an existing tool, which contain CSM in XML format. The Petri Nets produced by our transformation is in XML format. It can be used for validating the original models by simulation. The results from this analysis can be traced back to improve design decisions.
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Tatar, Mohammed I. "A method for the performance evaluation of computer systems based on Petri net simulations /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59432.
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This thesis presents a method for evaluating the performance of computer systems. The method is based on generating a graphical model of the system using Petri nets and simulating that model to obtain the required performance measures. The collected performance indexes are then analyzed to determine the functionality of the modeled system.The method we present is a hybrid implementation of two very powerful strategies, namely: Petri nets and object-oriented programming. The Petri net model is used to generate precise graphical representations that can model such aspects as synchronization, parallelism, control flow, and data flow. Furthermore, we will emphasize the capabilities of Petri nets to provide a model that can be easily evaluated using event-driven object-oriented simulations.
The simulation environment is based on the object-oriented capabilities of C++ (a super set of C) which provides an excellent tool for evaluating and analyzing Petri net models. The simulator utilizes the concepts of class hierarchies, application-specific instance variables, application-specific instance methods, and object interactions that are typical of object-oriented programming (OOP) languages. The simulator is capable of producing all the required information for calculating the performance measures of the system. It contains a dedicated scheduler and debugger, and can perform with a polynomial (of the second order) time complexity.
The method is mainly used for performance evaluation purposes in the areas of systems design and synthesis.
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Kabutz, Heinz Max. "Analytical performance evaluation of concurrent communicating systems using SLD and stochastic Petri nets." Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/13524.
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Bibliography: leaves 113-117.In this thesis, the performance analysis of SDL with a new type of stochastic Petri net is described. This new net is called SDL-net. The Concurrent Communicating System is described, and the need for qualitative and quantitative analysis of such systems is motivated. Formal methods are demonstrated which can be used to represent such Concurrent Communicating Systems. The Specification and Description Language (SDL) is shown in the context of Concurrent Communicating Systems and the software development cycle is described for SDL systems. Correctness and performance of SDL are discussed and it is shown how the semantics of time for performance can be introduced into SDL by adding external information, by extending the SDL syntax or by using compiler directives. In this thesis only external information is added.
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Inkpen, Christopher John. "The application of Petri-nets and stochastic processes to knowledge based project planning." Thesis, University of Brighton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305771.
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Reyes, Moro Antonio. "Scheduling of flexible manufacturing systems integrating Petri nets and artificial intelligence methods." Thesis, Liverpool John Moores University, 2000. http://researchonline.ljmu.ac.uk/5527/.
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The work undertaken in this thesis is about the integration of two well-known methodologies: Petri net (PN) model Ii ng/analysis of industrial production processes and Artificial Intelligence (AI) optimisation search techniques. The objective of this integration is to demonstrate its potential in solving a difficult and widely studied problem, the scheduling of Flexible Manufacturing Systems (FIVIS). This work builds on existing results that clearly show the convenience of PNs as a modelling tool for FIVIS. It addresses the problem of the integration of PN and Al based search methods. Whilst this is recognised as a potentially important approach to the scheduling of FIVIS there is a lack of any clear evidence that practical systems might be built. This thesis presents a novel scheduling methodology that takes forward the current state of the art in the area by: Firstly presenting a novel modelling procedure based on a new class of PN (cb-NETS) and a language to define the essential features of basic FIVIS, demonstrating that the inclusion of high level FIVIS constraints is straight forward. Secondly, we demonstrate that PN analysis is useful in reducing search complexity and presents two main results: a novel heuristic function based on PN analysis that is more efficient than existing methods and a novel reachability scheme that avoids futile exploration of candidate schedules. Thirdly a novel scheduling algorithm that overcomes the efficiency drawbacks of previous algorithms is presented. This algorithm satisfactorily overcomes the complexity issue while achieving very promising results in terms of optimality. Finally, this thesis presents a novel hybrid scheduler that demonstrates the convenience of the use of PN as a representation paradigm to support hybridisation between traditional OR methods, Al systematic search and stochastic optimisation algorithms. Initial results show that the approach is promising.
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Salum, Latif. "Improvements in manufacturing cell design based on new classes of high level Petri Nets." Thesis, Cranfield University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267499.
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Li, Yingmin. "Diagnosis of Large Software Systems Based on Colored Petri Nets." Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00551301.
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Cette thèse porte sur le diagnostic à base de modèles. Nous focalisons notre intérêt sur le diagnostic d'un ensemble interagissant de composants logiciels. L'originalité de ce travail se situe dans l'utilisation des Réseaux de Petri Colorés (RdPC) comme modèle de faute. L'utilisation des RdPC est originale et avantageuse à plusieurs titres. Premièrement, Les RdPC permettent la représentation des données, dans notre cas ça nous permet de manipuler les données de manière symbolique même si leur domaine de valeurs est infini (seul le statut des données est représenté par des jetons colorés : rouge pour fautif, noir pour correct et étoile pour inconnu). Deuxièmement, chaque transition en RdPC peut avoir plusieurs modalités de franchissement, nous avons donc défini pour chaque activité deux modalités de transition, fautif et correct, auxquelles on a associé des fonctions de propagation de couleur. Finalement, La sémantique RdPC porte de manière implicite la notion d'ordre partiel des observations. La contribution principale de cette thèse consiste à réduire le problème de diagnostic à la résolution d' un système d'inéquation algébrique en se fondant sur l'équation fondamentale de la dynamique des RdPs. La résolution de ce système d'inéquation permet de calculer le diagnostic sans dépliage de la trajectoire même dans les cas d'itération d'activités et ceci sans perte de la précision du diagnostic. Nous avons également, en se fondant sur la notion de sous-réseaux fonctionnels, proposé une version décentralisée de la résolution du système d'inéquation. La dimension applicative de cette thèse concerne le diagnostic d'orchestration de services Web. Une traduction du langage d'orchestration BPEL en RdPC a été donné ainsi qu'une application détaillée sur un scénario.
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Pong, Lih, and 龐立. "Formal data flow diagrams (FDFD): a petri-netbased requirements specification language." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207406.
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Scruggs, James N. "Power system availability determination through Petri net simulation." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178910568.
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Rodríguez, César. "Verification based on unfoldings of Petri nets with read arcs." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00927064.
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Humans make mistakes, especially when faced to complex tasks, such as the construction of modern hardware or software. This thesis focuses on machine-assisted techniques to guarantee that computers behave correctly. Modern computer systems are large and complex. Automated formal verification stands as an alternative to testing or simulation to ensuring their reliability. It essentially proposes to employ computers to exhaustively check the system behavior. Unfortunately, automated verification suffers from the state-space explosion problem: even relatively small systems can reach a huge number of states. Using the right representation for the system behavior seems to be a key step to tackle the inherent complexity of the problems that automated verification solves. The verification of concurrent systems poses additional issues, as their analysis requires to evaluate, conceptually, all possible execution orders of their concurrent actions. Petri net unfoldings are a well-established verification technique for concurrent systems. They represent behavior by partial orders, which not only is natural but also efficient for automatic verification. This dissertation focuses on the verification of concurrent systems, employing Petri nets to formalize them, and studies two prominent verification techniques: model checking and fault diagnosis. We investigate the unfoldings of Petri nets extended with read arcs. The unfoldings of these so-called contextual nets seem to be a better representation for systems exhibiting concurrent read access to shared resources: they can be exponentially smaller than conventional unfoldings on these cases. Theoretical and practical contributions are made. We first study the construction of contextual unfoldings, introducing algorithms and data structures that enable their efficient computation. We integrate contextual unfoldings with merged processes, another representation of concurrent behavior that alleviates the explosion caused by non-determinism. The resulting structure, called contextual merged processes, is often orders of magnitude smaller than unfoldings, as we experimentally demonstrate. Next, we develop verification techniques based on unfoldings. We define SAT encodings for the reachability problem in contextual unfoldings, thus solving the problem of detecting cycles of asymmetric conflict. Also, an unfolding-based decision procedure for fault diagnosis under fairness constraints is presented, in this case only for conventional unfoldings. Finally, we implement our verification algorithms, aiming at producing a competitive model checker intended to handle realistic benchmarks. We subsequently evaluate our methods over a standard set of benchmarks and compare them with existing unfolding-based techniques. The experiments demonstrate that reachability checking based on contextual unfoldings outperforms existing techniques on a wide number of cases. This suggests that contextual unfoldings, and asymmetric event structures in general, have a rightful place in research on concurrency, also from an efficiency point of view.
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Marsal, Gaëlle. "Evaluation of time performances of ethernet-based automation systems by simulation of high-level Petri nets." Cachan, Ecole normale supérieure, 2006. http://tel.archives-ouvertes.fr/tel-00162228.
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Nous évaluons dans cette thèse deux performances temporelles des architectures d’automatisation distribuées sur Ethernet commuté et utilisant un modèle de coopération client/serveur : Le temps de réponse entre une occurrence d’un événement d’entrée et l’occurrence de l’événement de sortie correspondant ; Le temps de cycle réeseau pour la scrutation par un contrôleur de l’ensemble de ses modules d’entrées / sorties déportées. La conjonction de trois mécanismes de consommation de temps rend ces deux performances variables et difficiles à déterminer de manière analytique. Par conséquent, la méthode proposée se base sur la simulation d’un modèle en réseau de Petri temporisé et coloré du comportement dynamique de l’architecture complète. Les résultats obtenus sur six architectures test permettent de : Montrer que les architectures multi-contrôleurs utilisant le modèle de coopération client / serveur donnent des temps de cycle réseau plus rapide que celles basées sur les modèles maître / esclave et producteur / consommateur ; Quantifier l’influence du réseau et des mécanismes de consommation du tempsIn this work, two time performances of switched Ethernet automation systems that use a client/server cooperation model are evaluated : The response time from an occurrence of an input event to the occurrence of the corresponding output event ; The network cycle time for the scanning by a controller of the whole set of its remote inputs / outputs modules. The conjunction of three time consumption mechanisms makes both time performances variable and difficult to compute in an analytic fashion. Thus, the proposed method is based on simulation of a timed and coloured Petri net model of the dynamic behaviour of the whole automation architecture. The results which have been obtained on six benchmark architectures enabled us : To show that multi-controllers architectures using a client/server cooperation model provide faster network cycle times than those based on master/slave and producer/consumer models ; To quantify the influence of the time consumption mechanisms on these performances
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Cortés, Luis Alejandro. "A Petri Net based Modeling and Verification Technique for Real-Time Embedded Systems." Licentiate thesis, Linköping University, Linköping University, ESLAB - Embedded Systems Laboratory, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5751.
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Embedded systems are used in a wide spectrum of applications ranging from home appliances and mobile devices to medical equipment and vehicle controllers. They are typically characterized by their real-time behavior and many of them must fulfill strict requirements on reliability and correctness.
In this thesis, we concentrate on aspects related to modeling and formal verification of realtime embedded systems.
First, we define a formal model of computation for real-time embedded systems based on Petri nets. Our model can capture important features of such systems and allows their representations at different levels of granularity. Our modeling formalism has a welldefined semantics so that it supports a precise representation of the system, the use of formal methods to verify its correctness, and the automation of different tasks along the design process.
Second, we propose an approach to the problem of formal verification of real-time embedded systems represented in our modeling formalism. We make use of model checking to prove whether certain properties, expressed as temporal logic formulas, hold with respect to the system model. We introduce a systematic procedure to translate our model into timed automata so that it is possible to use available model checking ools. Various examples, including a realistic industrial case, demonstrate the feasibility of our approach on practical applications.
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鄭則平 and Chuk-ping Cheng. "Noodle: a three-dimensional net-based object-oriented development environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211276.
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Cheng, Chuk-ping. "Noodle : a three-dimensional net-based object-oriented development environment /." [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13867659.
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Marsal, Gaelle [Verfasser]. "Evaluation of time performances of Ethernet-based Automation Systems by simulation of High-level Petri Nets / Gaelle Marsal." Aachen : Shaker, 2007. http://d-nb.info/1166512339/34.
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Mueller, Ralph. "Specification and Automatic Generation of Simulation Models with Applications in Semiconductor Manufacturing." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16147.
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The creation of large-scale simulation models is a difficult and time-consuming task. Yet simulation is one of the techniques most frequently used by practitioners in Operations Research and Industrial Engineering, as it is less limited by modeling assumptions than many analytical methods. The effective generation of simulation models is an important challenge. Due to the rapid increase in computing power, it is possible to simulate significantly larger systems than in the past. However, the verification and validation of these large-scale simulations is typically a very challenging task.
This thesis introduces a simulation framework that can generate a large variety of manufacturing simulation models. These models have to be described with a simulation data specification. This specification is then used to generate a simulation model which is described as a Petri net. This approach reduces the effort of model verification.
The proposed Petri net data structure has extensions for time and token priorities. Since it builds on existing theory for classical Petri nets, it is possible to make certain assertions about the behavior of the generated simulation model.
The elements of the proposed framework and the simulation execution mechanism are described in detail. Measures of complexity for simulation models that are built with the framework are also developed.
The applicability of the framework to real-world systems is demonstrated by means of a semiconductor manufacturing system simulation model.
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Wang, Renzhong. "Executable system architecting using systems modeling language in conjunction with Colored Petri Nets - a demonstration using the GEOSS network centric system." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Wang_09007dcc803a6d5e.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 30, 2007) Includes bibliographical references (p. 199-209).
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Ďuriš, Anton. "Simulace distribuovaných systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442811.
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This thesis is focused on distributed systems modeling using Petri nets. Distributed systems are increasingly being implemented in applications and computing systems, where their task is to ensure sufficient performance and stability for a large number of its users. When modeling a distributed systems, stochastic behavior of Petri nets is important, which will provide more realistic simulations. Therefore, this thesis focuses mainly on timed Petri nets. The theoretical part of this thesis summarizes distributed systems, their properties, types and available architectures, as well as Petri nets, their representation, types and the principle of an operation. In the practical part, two models were implemented, namely a horizontally scaled web application divided into several services with a distributed database and a large grid computing system, more precisely the BOINC platform with the Folding@home project. Both models were implemented using the PetNetSim library of Python. The goal of this thesis is to perform simulations on the created models for different scenarios of their behavior.
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Mahmood, Imran. "A Verification Framework for Component Based Modeling and Simulation : “Putting the pieces together”." Doctoral thesis, KTH, Programvaruteknik och Datorsystem, SCS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116678.
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The discipline of component-based modeling and simulation offers promising gains including reduction in development cost, time, and system complexity. This paradigm is very profitable as it promotes the use and reuse of modular components and is auspicious for effective development of complex simulations. It however is confronted by a series of research challenges when it comes to actually practice this methodology. One of such important issue is Composability verification. In modeling and simulation (M&S), composability is the capability to select and assemble components in various combinations to satisfy specific user requirements. Therefore to ensure the correctness of a composed model, it is verified with respect to its requirements specifications.There are different approaches and existing component modeling frameworks that support composability however in our observation most of the component modeling frameworks possess none or weak built-in support for the composability verification. One such framework is Base Object Model (BOM) which fundamentally poses a satisfactory potential for effective model composability and reuse. However it falls short of required semantics, necessary modeling characteristics and built-in evaluation techniques, which are essential for modeling complex system behavior and reasoning about the validity of the composability at different levels.In this thesis a comprehensive verification framework is proposed to contend with some important issues in composability verification and a verification process is suggested to verify composability of different kinds of systems models, such as reactive, real-time and probabilistic systems. With an assumption that all these systems are concurrent in nature in which different composed components interact with each other simultaneously, the requirements for the extensive techniques for the structural and behavioral analysis becomes increasingly challenging. The proposed verification framework provides methods, techniques and tool support for verifying composability at its different levels. These levels are defined as foundations of a consistent model composability. Each level is discussed in detail and an approach is presented to verify composability at that level. In particular we focus on theDynamic-Semantic Composability level due to its significance in the overallcomposability correctness and also due to the level of difficulty it poses in theprocess. In order to verify composability at this level we investigate the application ofthree different approaches namely (i) Petri Nets based Algebraic Analysis (ii) ColoredPetri Nets (CPN) based State-space Analysis and (iii) Communicating SequentialProcesses based Model Checking. All the three approaches attack the problem ofverifying dynamic-semantic composability in different ways however they all sharethe same aim i.e., to confirm the correctness of a composed model with respect to itsrequirement specifications. Beside the operative integration of these approaches inour framework, we also contributed in the improvement of each approach foreffective applicability in the composability verification. Such as applying algorithmsfor automating Petri Net algebraic computations, introducing a state-space reductiontechnique in CPN based state-space analysis, and introducing function libraries toperform verification tasks and help the molder with ease of use during thecomposability verification. We also provide detailed examples of using each approachwith different models to explain the verification process and their functionality.Lastly we provide a comparison of these approaches and suggest guidelines forchoosing the right one based on the nature of the model and the availableinformation. With a right choice of an approach and following the guidelines of ourcomponent-based M&S life-cycle a modeler can easily construct and verify BOMbased composed models with respect to its requirement specifications.Overseas Scholarship for PHD in selected Studies Phase II Batch I
Higher Education Commision of Pakistan.
QC 20130224
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Bucchianeri, Juliano Resende. "MODELAGEM DOS SISTEMAS DE PROTEÇÃO E FALHAS DE UMA SUBESTAÇÃO DE DISTRIBUIÇÃO UTILIZANDO REDES DE PETRI." Pontifícia Universidade Católica de Goiás, 2018. http://tede2.pucgoias.edu.br:8080/handle/tede/4070.
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The appropriated and secure supply of electrical energy directly impacts on the present society. The increase in demand favors the growth of electrical systems, especially in distribution networks and substations, since they are responsible for lowering the electrical voltage, allowing energy distribution to the population. To keep distribution networks and substations running, without interruption or discontinuity, is utmost importance for the maintenance of electric power supply, and it is necessary to implement means to locate and improve the electrical protections in order to reduce failures or to suspend the electricity distribution. Distribution failures may result from lightning, overcurrent, short circuits, overvoltages, oil leakage on transformers, impedance failure etc. The present work presents the problem of possible defects that result in the substation power blackout, and aims to reduce the amount and frequency of substation power blackouts, contributing to the increase in industrial production. In this regard, qualitative and quantitative models using Petri nets of an electrical substation of distribution were developed, using simulation scenarios to indicate possible improvements in the electrical protections, reducing the inaccuracies and interruptions.
O fornecimento adequado e seguro de energia elétrica impacta diretamente na sociedade atual. O aumento da demanda torna favorável o crescimento dos sistemas de eletricidade, sobretudo nas redes e subestações de distribuição, pois estas são responsáveis por rebaixar a tensão elétrica, permitindo assim distribuição de energia para a população. Manter as redes e subestações de distribuição funcionando, sem interrupções ou descontinuidade, é de suma importância para a manutenção do fornecimento de eletricidade, sendo necessário implementar meios para localizar e melhorar as proteções elétricas afim de diminuir as falhas ou a suspensão da distribuição desta. As falhas da distribuição podem resultar de descargas atmosféricas, sobrecorrente, curtoscircuitos, sobretensões, vazamento de óleo nos transformadores, falha de impedância etc. O presente trabalho expõe o problema dos possíveis defeitos que resultam no desligamento da subestação e objetiva reduzir a quantidade e a frequência dos desligamentos da subestação, colaborando para o aumento na produção industrial. Para isso, desenvolveu modelos qualitativos e quantitativos utilizando redes de Petri de uma subestação elétrica de distribuição, utilizando cenários de simulação para apontar possíveis melhorias nas proteções diminuindo as incorreções e interrupções.
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Cristini, Frédéric. "Amélioration de la résilience de systèmes spatiaux soumis à des menaces : vers des réseaux de satellites autonomes." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0025/document.
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Un environnement spatial naturel hostile, les systèmes spatiaux de télédétection traditionnels,monolithiques et téléopérés depuis le sol, demeurent vulnérables face à un nombre croissant de menaces émergentes issues de l’environnement spatial artificiel (armes antisatellites,débris). Plutôt que de chercher à protéger physiquement les satellites, nous proposons d’adopter une stratégie fondée sur le concept de résilience, qui traduit la capacité d’un système à poursuivre sa mission face à des aléas imprévisibles, fût-ce en mode dégradé. En nous appuyant sur de récentes innovations dans les technologies spatiales, nous nous sommes intéressés à la conception et à l’évaluation d’architectures système fondées sur la mise en réseau de constellations de microsatellites hétérogènes, autonomes et communicants.Afin d’étudier de telles architectures, appelées réseaux de constellations autonomes (RCA),nous proposons une approche de modélisation ainsi qu’un outil de simulation à base de réseaux de Petri imbriqués. Grâce à des métriques issues des réseaux de télécommunication ainsi que des systèmes multiagents, nous avons évalué les RCA au travers de leurs performances opérationnelles et de leurs capacités de communication, nominales puis dans divers modes dégradés. Du point de vue de la résilience, les résultats présentés mettent en évidence l’intérêt de disposer de réseaux de communication denses et de modules de reconfiguration autonomes embarqués au sein même des satellitesAlthough Earth observation space systems are designed with strong safety requirements due to an hostile natural space environment, they remain vulnerable to an increasing range of emerging space threats such as antisatellite weapons or orbital debris. Instead of a physical protection of these monolithic and remote-controlled assets, we propose a design strategy based on the concept of resilience which is the ability of a system to maintain an acceptable level of performance in the presence of unforeseeable disturbance.Thanks to the latest space technology innovations, we devised new system architectures composed of networked constellations of heterogeneous and autonomous interacting microsatellites. We decided to model these architectures, called autonomous networked constellations (RCA in French), thanks to Petri nets, and more specifically their nets-within-nets variant. Using telecommunication and multiagent metrics, we assessed different RCA configurations through their operational performance and communicability, for nominal as wellas degraded modes. From the resilience point of view, we present quantitative results that point out the benefits of dense space networks and embedded autonomous reconfiguration modules
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Hayrapetyan, Anush. "Formalized, validated and executable CPN models of SIP-based presence and dynamic discovery protocols for mobile applications." Click here for download, 2007. http://proquest.umi.com/pqdweb?did=1288671611&sid=2&Fmt=2&clientId=3260&RQT=309&VName=PQD.
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Oliveira, Ítalo Romani de. "Análise de risco da operação de espaçamento temporal aerotransportado por meio de um modelo em rede de Petri estocástica e dinamicamente colorida." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-09012008-164233/.
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A segurança do espaço aéreo pode aumentar consideravelmente com o uso de operações de espaçamento e separação aerotransportados. Sob este paradigma, a tarefa de manter distância em relação a outras aeronaves é delegada aos pilotos, que contarão com o Sistema de Assistência de Separação Aerotransportado (ASAS). Com este sistema, ainda em fase experimental, os pilotos tornam-se cientes dos riscos do tráfego circundante com até 15 minutos de antecedência, sem necessitar de auxílio dos controladores de tráfego aéreo. Esta antecedência é muito maior que a do atual sistema anti-colisão (TCAS), que é de menos de 1 minuto. O sistema ASAS utiliza uma tecnologia de comunicação mais avançada que a tecnologia do transponder modo C, utilizado atualmente pelo sistema anti-colisão. O novo sistema ASAS está sendo desenvolvido intensivamente no Eurocontrol e em outras iniciativas nos Estados Unidos da América, e funcionará em conjunto com o atual sistema anti-colisão, proporcionando redundância, ou seja: se o antigo sistema falhar, o novo ainda pode emitir um alerta, ou vice-versa. O presente trabalho de pesquisa aborda a aplicação do ASAS para aumentar a precisão do espaçamento entre aeronaves que chegam sequencialmente a um determinado aeroporto, por meio de um formalismo matemático denominado \"Rede de Petri Estocástica e Dinamicamente Colorida\", com a obtenção de dados quantitativos sobre o risco de acidente. Esses dados indicam que o risco de acidente é significativamente menor com o uso do ASAS do que sem o uso do ASAS.The safety in the airspace can considerably increase with the use of airborne spacing and separation operations. Under this paradigm, the task of maintaining a safe distance between aircraft is delegated to the pilots, which will be supported by the Airborne Separation Assistance System (ASAS). With this system, which is still in experimental phase, pilots become aware of the surrounding air traffic risks with up to 15 minutes in advance, without the help of air traffic controllers on the ground. This antecedence is much greater than the one provided by the current Traffic Collision Avoidance System (TCAS). ASAS uses a more advanced communication technology than Mode-C transponder, broadly used in the current civil aviation for collision avoidance purposes. The development of ASAS is being carried out intensively in Eurocontrol and in other initiatives in the United States of America, and this novel system is intended to work in parallel with the current collision avoidance systems, acting as safety nets. The present study approaches the ASAS application to improve the precision of spacing between aircraft that sequentially arrive at an airport, using the so called mathematical formalism \"Stochastically and Dynamically Coloured Petri Net\", for evaluating quantitative data about accident risk. These data indicate that the accident risk is significantly smaller when aircraft pairs use ASAS Spacing than when aircraft pairs do not use ASAS Spacing.
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LIU, Baisi. "An Efficient Approach for Diagnosability and Diagnosis of DES Based on Labeled Petri Nets, Untimed and Timed Contexts." Phd thesis, Ecole Centrale de Lille, 2014. http://tel.archives-ouvertes.fr/tel-01064597.
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Cette thèse s'intéresse à l'étude des problèmes de diagnostic des fautes sur les systèmes à événements discrets dans des contextes atemporel et temporel sur la base de modèles réseau de Petri. Des techniques d'exploration incrémentale et à-la-volée sont développées pour combattre le problème de l'explosion de l'espace d'état. Dans le contexte atemporel, une représentation algébrique pour les réseaux de Petri labellisés (RdP-L) a été développée pour caractériser le comportement du système. La diagnosticabilité de modèles RdP-L est ensuite abordée par l'analyse d'une série de problèmes d'analyse de K -diagnosticabilité, où K peut être augmenté progressivement. Concrètement, l'analyse de la diagnosticabilité est effectuée sur la base de deux modèles nommés respectivement FM-graph et FM-set tree qui sont développés à-la-volée et qui contiennent les informations relatives aux fautes. Un diagnostiqueur peut facilement être dérivé à partir du FM-set tree pour le diagnostic en ligne. Dans le contexte temporel, une technique de fractionnement des intervalles de temps a été élaborée pour développer une représentation de l'espace d'état des réseaux de Petri labellisés et temporels (RdP-LT) pour laquelle des techniques d'analyse de la diagnosticabilité du contexte atemporel, peuvent être exploitées. Sur cette base, les conditions nécessaires et suffisantes pour la diagnosticabilité de RdP-LT ont été déterminées, et nous présentons la solution pour le délai minimum qui assure la diagnosticabilité. En pratique, l'analyse de la diagnosticabilité est effectuée sur la base de la construction à-la-volée d'une structure que l'on appelle ASG et qui contient des informations relatives à l'occurrence de fautes sur les états du RdP-LT. D'une manière générale, l'analyse effectuée sur la base des techniques à-la-volée et incrémentale permet de construire et explorer seulement une partie de l'espace d'état. Les résultats des analyses effectuées sur certains benchmarks montrent l'efficacité des techniques que nous avons développées en termes de temps et de mémoire par rapport aux approches traditionnelles basées sur l'énumération des états.
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Palma, Jandira Guenka. "Metamodelo para a modelagem e simulação de sistemas a eventos discretos, baseado em redes de Petri e realidade virtual: uma aplicação em sistema de manufatura." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-10042017-151610/.
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Uma vez que uma aplicação ou projeto tenha sido identificado como sujeito ao uso da simulação, decisões devem ser tomadas acerca de como conduzir os estudos. Embora não haja regras definitivas, alguns passos são geralmente recomendados, tais como: planejamento do estudo, definição do sistema, construção do modelo, execução dos experimentos, análise dos resultados e relatório final. E, a construção do modelo é uma das etapas mais demoradas e complexas. Na execução dos experimentos, e na análise dos resultados a Realidade Virtual (RV) é uma interface que pode fornecer um suporte importante para a tomada de decisões, pois a RV auxilia na criação de mundos virtuais semelhantes ao mundo real, que ajudam na compreensão do funcionamento dos sistemas. Este trabalho propõe um metamodelo para o desenvolvimento de sistemas de simulação de eventos discretos com interface de RV aplicados a ambientes ou estações de trabalho de manufatura. A proposta do metamodelo é composto por quatro módulos: i) de edição e validação de modelos, ii) de criação, edição e execução de ambientes virtuais, iii) de conexão para efetuar o elo entre os dois primeiros módulos e, iv) de controle para gerenciar a comunicação e controlar a simulação. Como resultado tem-se a simulação centralizada baseada no modelo descrito em Rede de Petris (RP) com interface de RV distribuída. O sistema computacional gerado pelo metamodelo auxiliará no aprendizado e compreensão do problema simulado, e ainda permitirá ao usuário o envolvimento através da iteração.The VR aids in the creation of virtual worlds similar to the real world, helping in understanding how a system works. This research work is concerned with the development of a discrete-event system simulation based on Petri Nets, with Virtual Reality interface for manufacturing environment or workstations. The system is composed of four modules, the first is model editing and validation, the second module is a modeling tool for virtual objects and/or a library of virtual elements, the third module makes the link between the two previous modules, and finally, the fourth is a simulation and control module. The centralized simulation is based on models described by Petri Nets with distributed RV interface resulting in a flexible and consistent system. The system will help users in learning and understanding the simulation problem, and it will also allow the user\'s integration with the environment through the interaction, and through distributed interface.
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Santos, Rossini Sálvio Bomfim dos. "Modelagem e análise de performance de sistemas flexíveis de manufatura baseado em redes de Petri temporizadas: estudo de caso na indústria automobilística." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-02102008-164301/.
Full textAbstract:
A necessidade de aumento de produção, da redução de custos e do aumento da qualidade de bens de consumo, tem motivado a constante evolução dos sistemas de produção, migrando os tradicionais sistemas de produção para os modernos e complexos sistemas de manufatura, onde a performance depende da eficiência dos equipamentos e do controle do processo. Por outro lado, a eficiência dos equipamentos depende de sua confiabilidade e manutenabilidade. Neste trabalho a análise de performance é avaliada com o uso de Rede de Petri p-t-Temporizada e através de simulações, incluindo a avaliação da confiabilidade do processo pela análise da otimização da saída do sistema, isto é, quantidade de itens produzidos. Nesta abordagem, uma lógica linear foi desenvolvida e validada utilizando-se uma comparação de resultados das classes de estados do algoritmo proposto com a ferramenta de simulação Tina para um modelo de um esquema produtor consumidor. Apresenta-se um estudo de caso na indústria automotiva, consistindo na análise dos problemas reais enfrentados em uma fábrica de carrocerias, com o uso da Rede de Petri p-t-Temporizada.The necessity of growing in production, with reduction of costs and improvement in the quality of consumption good, has motivated the constant evolution of production systems, transforming traditional production systems into the modern and complex manufacturing systems, where the performance depends on the efficiency of the equipment and process control. On the other hand, the equipment efficiency depends of their reliability and maintainability. In this work it is proposed a performance evaluation and analysis with the use of p-t- Timed Petri Nets using simulations, including process reliability analysis of the system through the throughput optimization, i.e., produced amount of goods. In this approach, a linear logic statement was developed and validated using a comparison of results of classes of states between the Tina simulation environment and the algorithm considered for a model of a producing consuming system. A case study in the automotive industry is presented, consisting of the analysis of the real problems found in a body shop plant, with the use of Timed Petri Net.