5,822 research outputs found
ConStaBL -- A Fresh Look at Software Engineering with State Machines
Statechart is a visual modelling language for systems. In this paper, we
extend our earlier work on modular statecharts with local variables and present
an updated operational semantics for statecharts with concurrency. Our variant
of the statechart has local variables, which interact significantly with the
remainder of the language semantics. Our semantics does not allow transition
conflicts in simulations and is stricter than most other available semantics of
statecharts in that sense. It allows arbitrary interleaving of concurrently
executing action code, which allows more precise modelling of systems and
upstream analysis of the same. We present the operational semantics in the form
of the simulation algorithm. We also establish the criteria based on our
semantics for defining conflicting transitions and valid simulations. Our
semantics is executable and can be used to simulate statechart models and
verify their correctness. We present a preliminary setup to carry out fuzz
testing of Statechart models, an idea that does not seem to have a precedent in
literature. We have used our simulator in conjunction with a well-known fuzzer
to do fuzz testing of statechart models of non-trivial sizes and have found
issues in them that would have been hard to find through inspection.Comment: 24 page
Towards a new methodology for design, modelling, and verification of reconfigurable distributed control systems based on a new extension to the IEC 61499 standard
In order to meet user requirements and system environment changes, reconfigurable control systems must dynamically adapt their structure and behaviour without disrupting system operation. IEC 61499 standard provides limited support for the design and verification of such systems. In fact, handling different reconfiguration scenarios at runtime is difficult since function blocks in IEC 61499 cannot be changed at run-time. Hence, this thesis promotes an IEC 61499 extension called reconfigurable function block (RFB) that increases design readability and smoothly switches to the most appropriate behaviour when a reconfiguration event occurs. To ensure system feasibility after reconfiguration, in addition to the qualitative verification, quantitative verification based on probabilistic model checking is addressed in a new RFBA approach. The latter aims to transform the designed RFB model automatically into a generalised reconfigurable timed net condition/event system model (GRTNCES) using a newly developed environment called RFBTool. The GR-TNCES fits well with RFB and preserves its semantic. Using the probabilistic model checker PRISM, the generated GR-TNCES model is checked using defined properties specified in computation tree logic. As a result, an evaluation of system performance and an estimation of reconfiguration risks are obtained. The RFBA methodology is applied on a distributed power system case study.Dynamische Anforderungen und Umgebungen erfordern rekonfigurierbare Anlagen und Steuerungssysteme. Rekonfiguration ermöglicht es einem System, seine Struktur und sein Verhalten an interne oder externe Änderungen anzupassen. Die Norm IEC 61499 wurde entwickelt, um (verteilte) Steuerungssysteme auf Basis von Funktionsbausteinen zu entwickeln. Sie bietet jedoch wenig Unterstützung für Entwurf und Verifikation. Die Tatsache, dass eine Rekonfiguration das System-Ausführungsmodell verändert, erschwert die Entwicklung in IEC 61499 zusätzlich. Daher schlägt diese Dissertation rekonfigurierbare Funktionsbausteine (RFBs) als Erweiterung der Norm vor. Ein RFB verarbeitet über einen Master-Slave-Automaten Rekonfigurationsereignisse und löst das entsprechende Verhalten aus. Diese Hierarchie trennt das Rekonfigurationsmodell vom Steuerungsmodell und vereinfacht so den Entwurf. Die Funktionalität des Entwurfs muss verifiziert werden, damit die Ausführbarkeit des Systems nach einer Rekonfiguration gewährleistet ist. Hierzu wird das entworfene RFB-Modell automatisch in ein generalised reconfigurable timed net condition/event system übersetzt. Dieses wird mit dem Model-Checker PRISM auf qualitative und quantitative Eigenschaften überprüft. Somit wird eine Bewertung der Systemperformanz und eine Einschätzung der Rekonfigurationsrisiken erreicht. Die RFB-Methodik wurde in einem Softwarewerkzeug umgesetzt und in einer Fallstudie auf ein dezentrales Stromnetz angewendet
Developing a distributed electronic health-record store for India
The DIGHT project is addressing the problem of building a scalable and highly available information store for the Electronic Health Records (EHRs) of the over one billion citizens of India
Component-based control system development for agile manufacturing machine systems
It is now a common sense that manufactures including machine suppliers and system
integrators of the 21 st century will need to compete on global marketplaces, which are
frequently shifting and fragmenting, with new technologies continuously emerging.
Future production machines and manufacturing systems need to offer the "agility"
required in providing responsiveness to product changes and the ability to
reconfigure. The primary aim for this research is to advance studies in machine
control system design, in the context of the European project VIR-ENG - "Integrated
Design, Simulation and Distributed Control of Agile Modular Machinery"
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