Timed petri net models of ATM LANs

The Asynchronous Transfer Mode (ATM) is a fast packet-switching communication method using small fixed-length cells. A model of an ATM LAN is presented which provides a realistic representation of data transmission by modeling both the ATM network and the applications running over it. Colored Petri nets are used to create a compact model that is capable of representing a variety of different protocols at a high level of detail. The model is designed to allow easy reconfiguration or addition of details at different levels of the system. Simulation is used to evaluate the performance of the modeled system, and some results are compared to actual data gathered from the campus network at Memorial University

Modeling and performance analysis of ATM LANs

Asynchronous Transfer Mode (ATM} is a method of data transmission using small fixed-length cells. This thesis presents a model of an ATM LAN which provides a realistic representation of data transmission over the system by explicitly modeling both the ATM network and the applications running over that network. Coloured timed Petri nets are used to create a compact model that is capable of representing a variety of different protocols at a high level of detail. The model is designed to allow easy reconfiguration or addition of detail at different levels of the system. Simulation is used to evaluate the performance of the model, and results are compared to actual data gathered from the Memorial University campus network

State Space Reduction on Wireless Sensor Network Verification Using Component-Based Petri Net Approach

With the recent advancement of Internet of Things, the applications of Wireless Sensor Networks (WSNs) are increasingly attracting attention from of both industry and research communities. However, since the deployment cost of a WSN is relatively large, one would want to make a logic model of a WSN and have the model verified beforehand to ensure that the WSN would work correctly and effectively once practically employed. Petri Net (PN) is very suitable to model a WSN, since PN strongly supports modeling concurrent and ad-hoc systems. However, verification of a PN-modeled system suffers from having to explore the huge state space of the system. In order to overcome it, in this paper we suggest a novel component-based approach to model and verify a PN-modeled WSN system. First of all, the original WSN system is divided into components, which can be further abstracted to reduce the model size. Moreover, when verifying the corresponding PN model produced from the abstracted WSN, we introduce a strategy of component-based firing, which can reduce the state space significantly. Compared to typical approach of PN-based verification, our method enjoys an impressive improvement of performance and resource consuming, as depicted in our experimental results

Ad hoc network security and modeling with stochastic petri nets

Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. These networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. Unlike the existing commercial wireless systems and fixed infrastructure networks, they do not rely on specialized routers for path discovery and traffic routing. Security is an important issue in such networks. Typically, mobile nodes are significantly more susceptible to physical attacks than their wired counterparts. This research intends to investigate the ad hoc network routing security by proposing a performance enhanced Secure ad hoc On-demand Routing protocol (SOR). Specifically, it presents a method to embed Security Level into ad hoc on-demand routing protocols using node-disjoint multipath, and to use maximum hopcount to restrict the number of routing packets in a specific area. The proposed scheme enables the use of security as a marked factor to improve the relevance of the routes discovered by ad hoc routing protocols. It provides customizable security to the flow of routing protocol messages. In general, SOR offers an alternative way to implement security in on-demand routing protocols. Ad hoc network is too complex to allow analytical study for explicit performance expressions. This research presents a Stochastic Petri net-based approach to modeling and analysis of mobile ad hoc network. This work illustrates how this model is built as a scalable model and used to exploit the characteristics of the networks. The proposed scheme is a powerful analytical model that can be used to derive network performance much more easily than a simulation-based approach. Furthermore, the proposed model is extended to study the performance of ad hoc network security by adding multipath selection and security measurement parameters. This research gives a quantificational measurement to analyze the performance of a modified SPN model under the effect of multipath and attack of a hypothetical compromised node

A petri-net based methodology for modeling, simulation, and control of flexible manufacturing systems

Global competition has made it necessary for manufacturers to introduce such advanced technologies as flexible and agile manufacturing, intelligent automation, and computer-integrated manufacturing. However, the application extent of these technologies varies from industry to industry and has met various degrees of success. One critical barrier leading to successful implementation of advanced manufacturing systems is the ever-increasing complexity in their modeling, analysis, simulation, and control. The purpose of this work is to introduce a set of Petri net-based tools and methods to address a variety of problems associated with the design and implementation of flexible manufacturing systems (FMSs). More specifically, this work proposes Petri nets as an integrated tool for modeling, simulation, and control of flexible manufacturing systems (FMSs). The contributions of this work are multifold. First, it demonstrates a new application of PNs for simulation by evaluating the performance of pull and push diagrams in manufacturing systems. Second, it introduces a class of PNs, Augmented-timed Petri nets (ATPNs) in order to increase the power of PNs to simulate and control flexible systems with breakdowns. Third, it proposes a new class of PNs called Realtime Petri nets (RTPNs) for discrete event control of FMS s. The detailed comparison between RTPNs and traditional discrete event methods such as ladder logic diagrams is presented to answer the basic question \u27Why is a PN better tool than ladder logic diagram?\u27 and to justify the PN method. Also, a conversion procedure that automatically generates PN models from a given class of logic control specifications is presented. Finally, a methodology that uses PNs for the development of object-oriented control software is proposed. The present work extends the PN state-of-the-art in two ways. First, it offers a wide scope for engineers and managers who are responsible for the design and the implementation of modem manufacturing systems to evaluate Petri nets for applications in their work. Second, it further develops Petri net-based methods for discrete event control of manufacturing systems

Supporting Real-Time Communication in CSMA-Based Networks : the VTP-CSMA Virtual Token Passing Approach

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

Reliability analysis of multiplex control system of subsea blowout preventer based on stochastic Petri net

Višestruki (MUX − multiplex) upravljački sustav za sprečavanje podmorske erupcije bušotine (BOP − blowout preventer) ima bitnu ulogu u stvaranju sigurnih radnih uvjeta kod podmorskih aktivnosti bušenja. U skladu s radnim stanjima i kritičnim načinima kvara višestrukog upravljačkog sustava, u radu se predstavlja njegov stohastički model Petri mreža (SPN), uzimajući u obzir nesavršenu sposobnost otkrivanja greške. Predlaže se metoda numeričke analize temeljena na istolikom (izomorfnom) trajnom Markovljevom lancu modela. Istraživani su i uspoređivani pokazatelji pouzdanosti, odnosno pouzdanost, raspoloživost i MTTF višestrukog (MUX) upravljačkog sustava i probnog hidrauličkog upravljačkog sustava. Uz to, istraživani su učinci faktora prikrivenosti grešaka na vjerojatnosti stanja i dostupnost MUX upravljačkog sustava, a izvršena je i analiza nesigurnosti brzina paljenja u odnosu na MTTF.The multiplex (MUX) control system of subsea blowout preventer (BOP) plays a vital role in providing safe working conditions for the subsea drilling activities. According to the working states and critical failure modes of the MUX control system, this paper presents its stochastic Petri nets (SPN) model, taking into account the imperfect fault detection capacity. The numerical analysis method is proposed based on the isomorphic continuous-time Markov chain of the model. The reliability indexes, namely reliability, availability and MTTF of the MUX control system and pilot hydraulic control system are obtained and compared. In addition, the effects of fault coverage factor on state probabilities and availability of the MUX control system are researched and the uncertainty analysis of the firing rates related to MTTF is also performed

Second Workshop on Practical Use of Coloured Petri Nets and Design/CPN.

This report contains the proceedings of the Second Workshop on Practical Use of Coloured Petri Nets and Design/CPN, October 13-15, 1999. The workshop was organised by the CPN group at the Department of Computer Science at the University of Aarhus, Denmark. The individual papers are available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop99

WiMAX (IEEE 802.16)-profıbus arabağlaşım elemanının petri ağlarla modellenmesi ve performans analizi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Endüstriyel kontrol uygulamalarında saha seviyesindeki dağıtık kontrolör cihazların haberleşmesinde sahayolu ağları kullanılmaktadır. PROFIBUS (PROcess FIeld BUS) uluslararası standartlarla (IEC61158, EN50170) tanımlanmış en popüler sahayoludur. Üretim (fabrika), süreç ve bina otomasyon uygulamalarında yaygın olarak kullanılan PROFIBUS, 100 m ile 1200 m mesafede 9.6 kbps ile 12 Mbps arasındaki iletişim hızlarını desteklemektedir. Bu durum, PROFIBUS'ın daha geniş kapsama alanları ve yüksek hızlarda kullanılabilmesi için omurga teknolojisine sahip arabağlaşım elemanlarının kullanımını gerektirir.Arabağlaşım için kullanılan omurga protokolü gereksinimleri gelişen teknolojilerle birlikte değişmektedir. Günümüzde, kurulum kolaylığı ve hareketlilik avantajlarından dolayı kablolu omurga çözümlerine karşılık, kablosuz omurga çözümleri de kullanılmaya başlanmış ve hızla yaygınlaşmaktadır. Kablosuz genişbant omurga teknolojisi olan IEEE 802.16-WiMAX, görüş hattında 50 km'lik bir kapsama alanı, 120 Mbps veri transfer hızı ve farklı servis sınıflarında (UGS, rtPS, nrtPS, BE, ErtPS) hizmet kalitesi sunan bir protokoldür.Bu çalışmada, farklı lokasyonlardaki PROFIBUS segmentlerini IEEE 802.16-WiMAX kablosuz omurga teknolojisi üzerinden UGS servis sınıfı kullanarak birbirine bağlayan bir arabağlaşım birimi önerilmektedir. Bu birimin, senkronizasyon, koşutzamanlılık, kilitlenmeyi önleyebilme, üstel dağılım ve sabit zaman gecikme özellikleri olan Genelleştirilmiş Stokastik Petri Ağlar modeli sunulmaktadır. Ayrıca, model içerisinde PROFIBUS paketlerinin IEEE 802.16 paketleri içerisine kapsüllendiği önerilmektedir.Tasarlanan PROFIBUS/IEEE 802.16-WiMAX arabağlaşım birimi, geçit çıkış tampon boyutu, geçit giriş tampon boyutu, master istasyon jeton tutma süresi ve geçit PROFIBUS ayağı jeton tutma süresi parametrelerine bakılarak değerlendirilmiştir. Benzetimlerden alınan sonuçlar, arabağlaşım biriminin, farklı yükler altında yeterli bir hizmet sağladığını ve fiziksel gerçeklemesini yapacak olan kişiler için de başarımı ölçülebilir bir tasarım modeli sunduğunu göstermektedir.In the application of industrial controlling, fieldbuses are used in the communication of distributed controller devices at field layer. PROFIBUS (PROcess FIeld BUS) which is defined with the international standards (IEC61158, EN50170) is the most popular fieldbus. PROFIBUS which is used frequently in manufacturing (factory), process and building automations, provides datarates from 9.6 kbps to 12 Mbps at distance from 100 to 1200 meters. This situation requires using of internetworking units which has backbone technology, for using PROFIBUS at more coverage area and high datarates.The requirements of a backbone protocol used for internetworking, are changed by the development in technology. Nowadays, because of advantages of easiness in installation and mobility, in addition to the wired backbone solutions, wireless backbone solutions began to be used and rapidly became common. As a wireless broadband backbone technology, IEEE 802.16-WiMAX is a protocol that can serve a 50 km coverage area, a 120 Mbps datarate and a QoS at different service classes (UGS, rtPS, nrtPS, BE, ErtPS) in line-of-sight.In this study, an internetworking unit is proposed that interconnects PROFIBUS segments placed at different locations through a wireless backbone technology of IEEE 802.16-WiMAX by using UGS service class. By the features of synchronization, concurrent, deadlock avoidance, exponential distribution and constant time delay, Generalized Stochastic Petri Nets model of the unit is done. Also in the model, it is proposed that PROFIBUS packets are encapsulated into IEEE 802.16 packets.The designed PROFIBUS/IEEE 802.16-WiMAX internetworking unit is analyzed according to gateway output buffer size, gateway input buffer size, master station token holding time and gateway PROFIBUS side token holding time parameters. The outputs of simulations show that internetworking unit can support a sufficient service under different loads and present a designed model with a measurable performance for the people who want to implement it physically