Bisimilarity and Behaviour-Preserving Reconfigurations of Open Petri Nets

We propose a framework for the specification of behaviour-preserving reconfigurations of systems modelled as Petri nets. The framework is based on open nets, a mild generalisation of ordinary Place/Transition nets suited to model open systems which might interact with the surrounding environment and endowed with a colimit-based composition operation. We show that natural notions of bisimilarity over open nets are congruences with respect to the composition operation. The considered behavioural equivalences differ for the choice of the observations, which can be single firings or parallel steps. Additionally, we consider weak forms of such equivalences, arising in the presence of unobservable actions. We also provide an up-to technique for facilitating bisimilarity proofs. The theory is used to identify suitable classes of reconfiguration rules (in the double-pushout approach to rewriting) whose application preserves the observational semantics of the net.Comment: To appear in "Logical Methods in Computer Science", 41 page

Modeling and formal verification of probabilistic reconfigurable systems

In this thesis, we propose a new approach for formal modeling and verification of adaptive probabilistic systems. Dynamic reconfigurable systems are the trend of all future technological systems, such as flight control systems, vehicle electronic systems, and manufacturing systems. In order to meet user and environmental requirements, such a dynamic reconfigurable system has to actively adjust its configuration at run-time by modifying its components and connections, while changes are detected in the internal/external execution environment. On the other hand, these changes may violate the memory usage, the required energy and the concerned real-time constraints since the behavior of the system is unpredictable. It might also make the system's functions unavailable for some time and make potential harm to human life or large financial investments. Thus, updating a system with any new configuration requires that the post reconfigurable system fully satisfies the related constraints. We introduce GR-TNCES formalism for the optimal functional and temporal specification of probabilistic reconfigurable systems under resource constraints. It enables the optimal specification of a probabilistic, energetic and memory constraints of such a system. To formally verify the correctness and the safety of such a probabilistic system specification, and the non-violation of its properties, an automatic transformation from GR-TNCES models into PRISM models is introduced. Moreover, a new approach XCTL is also proposed to formally verify reconfigurable systems. It enables the formal certification of uncompleted and reconfigurable systems. A new version of the software ZIZO is also proposed to model, simulate and verify such GR-TNCES model. To prove its relevance, the latter was applied to case studies; it was used to model and simulate the behavior of an IPV4 protocol to prevent the energy and memory resources violation. It was also used to optimize energy consumption of an automotive skid conveyor.In dieser Arbeit wird ein neuer Ansatz zur formalen Modellierung und Verifikation dynamisch rekonfigurierbarer Systeme vorgestellt. Dynamische rekonfigurierbare Systeme sind in vielen aktuellen und zukünftigen Anwendungen, wie beispielsweise Flugsteuerungssystemen, Fahrzeugelektronik und Fertigungssysteme zu finden. Diese Systeme weisen ein probabilistisches, adaptives Verhalten auf. Um die Benutzer- und Umgebungsbedingungen kontinuierlich zu erfüllen, muss ein solches System seine Konfiguration zur Laufzeit aktiv anpassen, indem es seine Komponenten, Verbindungen zwischen Komponenten und seine Daten modifiziert (adaptiv), sobald Änderungen in der internen oder externen Ausführungsumgebung erkannt werden (probabilistisch). Diese Anpassungen dürfen Beschränkungen bei der Speichernutzung, der erforderlichen Energie und bestehende Echtzeitbedingungen nicht verletzen. Eine nicht geprüfte Rekonfiguration könnte dazu führen, dass die Funktionen des Systems für einige Zeit nicht verfügbar wären und potenziell menschliches Leben gefährdet würde oder großer finanzieller Schaden entstünde. Somit erfordert das Aktualisieren eines Systems mit einer neuen Konfiguration, dass das rekonfigurierte System die zugehörigen Beschränkungen vollständig einhält. Um dies zu überprüfen, wird in dieser Arbeit der GR-TNCES-Formalismus, eine Erweiterung von Petrinetzen, für die optimale funktionale und zeitliche Spezifikation probabilistischer rekonfigurierbarer Systeme unter Ressourcenbeschränkungen vorgeschlagen. Die entstehenden Modelle sollen über probabilistische model checking verifiziert werden. Dazu eignet sich die etablierte Software PRISM. Um die Verifikation zu ermöglichen wird in dieser Arbeit ein Verfahren zur Transformation von GR-TNCES-Modellen in PRISM-Modelle beschrieben. Eine neu eingeführte Logik (XCTL) erlaubt zudem die einfache Beschreibung der zu prüfenden Eigenschaften. Die genannten Schritte wurden in einer Softwareumgebung für den automatisierten Entwurf, die Simulation und die formale Verifikation (durch eine automatische Transformation nach PRISM) umgesetzt. Eine Fallstudie zeigt die Anwendung des Verfahren

Measurements, Models, Systems and Design

531 s.

Formalization of Petri Nets with Individual Tokens as Basis for DPO Net Transformations

Reconfigurable place/transition systems are Petri nets with initial markings and a set of rules which allow the modification of the net structure during runtime. They have been successfully used in different areas like mobile ad-hoc networks. In most of these applications the modification of net markings during runtime is an important issue. This requires the analysis of the interaction between firing and rule-based modification. For place/transition systems this analysis has been started explicitly without using the general theory of M-adhesive transformation systems, because firing cannot be expressed by rule-based transformations for P/T systems in this framework. This problem is solved in this paper using the new approach of P/T nets with individual tokens. In our main results we show that on one hand this new approach allows to express firing by transformation via suitable transition rules. On the other hand transformations of P/T nets with individual tokens can be shown to be an instance ofM-adhesive transformation systems, such that several well-known results, like the local Church-Rosser theorem, can be applied. This avoids a separate conflict analysis of token firing and transformations. Moreover, we compare the behavior of P/T nets with individual tokens with that of classical P/T nets. Our new approach is also motivated and demonstrated by a network scenario modeling a distributed communication system

Design and Management of Manufacturing Systems

Although the design and management of manufacturing systems have been explored in the literature for many years now, they still remain topical problems in the current scientific research. The changing market trends, globalization, the constant pressure to reduce production costs, and technical and technological progress make it necessary to search for new manufacturing methods and ways of organizing them, and to modify manufacturing system design paradigms. This book presents current research in different areas connected with the design and management of manufacturing systems and covers such subject areas as: methods supporting the design of manufacturing systems, methods of improving maintenance processes in companies, the design and improvement of manufacturing processes, the control of production processes in modern manufacturing systems production methods and techniques used in modern manufacturing systems and environmental aspects of production and their impact on the design and management of manufacturing systems. The wide range of research findings reported in this book confirms that the design of manufacturing systems is a complex problem and that the achievement of goals set for modern manufacturing systems requires interdisciplinary knowledge and the simultaneous design of the product, process and system, as well as the knowledge of modern manufacturing and organizational methods and techniques

Safety in Supervisory Control for Critical Systems

Part 10: Control and DecisionInternational audienceRecent studies show the designs of automated systems are becoming increasingly complex to meet the global competitive market. Additionally, organizations have focused on policies to achieve people’s safety and health, environmental management system, and controlling of risks, based on standards. In this context, any industrial system in the event of a fault that is not diagnosed and treated correctly could be considered to pose a serious risk to people’s health, to the environment and to the industrial equipment. According to experts, the concept of Safety Instrumented Systems (SIS) is a practical solution to these types of issues. They strongly recommend layers for risk reduction based on control systems organized hierarchically in order to manage risks, preventing or mitigating faults, or to bringing the process to a safe state. Additionally, the concept of Risk and Hazard Control can be applied to accomplish the required functionalities. It is based on problem solving components and considers a cooperative way to find a control solution. In this context, the software architecture can be based on a service-oriented architecture (SOA) approach. This paper initially proposes a new architecture for design of safety control systems for critical systems, based on Safety Supervisory Control Architecture, in accordance with standards IEC 61508 and IEC 61511. Furthermore, a method is also proposed for design the control layer of risk prevention within Safety Supervisory Control Architecture

Engineering framework for service-oriented automation systems

Tese de doutoramento. Engenharia Informática. Universidade do Porto. Faculdade de Engenharia. 201

Formal Models for Biological Systems

In the last thirty years, formal models have been thoroughly employed in the realm of biological systems for many reasons: (i) preventing those ambiguities that may arise when informal notations are used for system description, (ii) supporting the development of simulators, (iii) supporting the development of tools, such as model checkers, allowing for verifying whether a system satisfies a given behavioural property, (iv) offering several instruments allowing for comparing the behaviour of different systems. The work in this thesis can be divided into two contributions concerning formal models for biological systems. The first contribution is related to the study of the robustness of biochemical networks. In particular, we take inspiration from the notion of alpha-robustness, which, intuitively, verifies how by varying the initial concentration of some species, called conventionally the input species, the concentration of other species of interest, called the output species, varies at steady state. Robustness in our sense captures random effects and temporary effects that are typical of the stochastic model. We will employ: (i) the process calculi approach for specifying systems of interest, (ii) the semantic model of evolution sequences, which, intuitively, model the behaviour of a system as the sequence of probability measures over the attainable configurations, (iii) a formal notion of robustness, defined on the semantic model, and (iv) an algorithm allowing us to estimate the robustness of a system starting from its specification. We validate our approach on three case studies EnvZ/OmpR Osmoregulatory Signaling System in Escherichia Coli, which is an example of the regulatory network, the mechanism of Bacterial Chemotaxis of Escherichia Coli, and an abstract chemical reaction network, called Enzyme Activity at Saturation. We have provided a Python implementation available at https://github.com/dmanicardi/spebnr. Our second contribution is showing how the features of CospanSpan(Graph) can be exploited in modelling biological systems. CospanSpan(Graph) offers an algebraic approach for the compositional description of variable topology networks that has been only partially exploited so far for the formalisation of that kind of systems. In particular, we provide a simplified model of a human heart and a model of a dual-chamber pacemaker that can interact with the model of the heart. Then, we model a gene regulatory network, namely the Lac Operon of Escherichia Coli.In the last thirty years, formal models have been thoroughly employed in the realm of biological systems for many reasons: (i) preventing those ambiguities that may arise when informal notations are used for system description, (ii) supporting the development of simulators, (iii) supporting the development of tools, such as model checkers, allowing for verifying whether a system satisfies a given behavioural property, (iv) offering several instruments allowing for comparing the behaviour of different systems. The work in this thesis can be divided into two contributions concerning formal models for biological systems. The first contribution is related to the study of the robustness of biochemical networks. In particular, we take inspiration from the notion of alpha-robustness, which, intuitively, verifies how by varying the initial concentration of some species, called conventionally the input species, the concentration of other species of interest, called the output species, varies at steady state. Robustness in our sense captures random effects and temporary effects that are typical of the stochastic model. We will employ: (i) the process calculi approach for specifying systems of interest, (ii) the semantic model of evolution sequences, which, intuitively, model the behaviour of a system as the sequence of probability measures over the attainable configurations, (iii) a formal notion of robustness, defined on the semantic model, and (iv) an algorithm allowing us to estimate the robustness of a system starting from its specification. We validate our approach on three case studies EnvZ/OmpR Osmoregulatory Signaling System in Escherichia Coli, which is an example of the regulatory network, the mechanism of Bacterial Chemotaxis of Escherichia Coli, and an abstract chemical reaction network, called Enzyme Activity at Saturation. We have provided a Python implementation available at https://github.com/dmanicardi/spebnr. Our second contribution is showing how the features of CospanSpan(Graph) can be exploited in modelling biological systems. CospanSpan(Graph) offers an algebraic approach for the compositional description of variable topology networks that has been only partially exploited so far for the formalisation of that kind of systems. In particular, we provide a simplified model of a human heart and a model of a dual-chamber pacemaker that can interact with the model of the heart. Then, we model a gene regulatory network, namely the Lac Operon of Escherichia Coli