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Causality plays an important role in qualitative reasoning about physical systems. In this paper we show that the bond-graph method can be fruitfully applied to represent and generate causal order on a formal basis. Both physical and computational aspects of bond-graph causality are discussed. In particular we show that it provides a (inner physical(More)
  • Jan-Erik Strr, Jan Top, Ulf Ss Oderman
  • 1993
Current approaches to the problem of switching between modes in continuous dynamic system models tend to confound modelling and computation. Here we introduce an alternative approach ensuring a clear distinction between the physical and computational levels. Our method is centered around the idea that the variability of causal directions should be accepted(More)
Modelling and simulation are widely used methods in design and other engineering tasks. Providing libraries of reusable model fragments is a promising way of supporting engineering modelling. The paper discusses means of structuring such libraries in a generic and reusable way. Model content facts can be organized on the basis of the ontologies that are(More)
Setting up a simulation model is more than writing down state equations and running them on a computer. A lot of conceptual information about the physics and engineering aspects of the system must be taken into account to construct a useful simulation model. The role of a model library is to manage this information and to make model fragments reusable. This(More)
This paper describes the Ontology of units of Measure and related concepts (OM), an OWL ontology of the domain of quantities and units of measure. OM supports making quantitative research data more explicit, so that the data can be integrated, verified and reproduced. The various options for modeling the domain are discussed. For example, physical(More)
Formal veriication of safety and timing properties of engineering systems is only meaningful if based on models which are systematically derived. In this paper we report on our experience using switched bond graphs for the modelling of hardware components in hybrid systems. We present the basic ideas underlying bond graphs in general and switched bond(More)
A vast amount of information sources is stored as relational-like data and inaccessible to RDFS-based systems. In this paper we describe an approach to integration such information sources with RDFS-aware systems. The proposed solution is purely RDFS-based. We use RDF/S as a mechanism to specify and perform linking of relational data and a predefined domain(More)