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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)
In an attempt to characterize an unusual mycobacterial strain isolated from a 2-year-old Somali patient with lymphadenitis, we applied various molecular methods not previously used for the taxonomic classification of mycobacteria. This isolate, designated So93, did not differ from Mycobacterium tuberculosis in the biochemical tests and in its 16S rRNA(More)
In the USA, vancomycin-resistant Enterococcus faecium (VREF) is endemic in hospitals, despite lack of carriage among healthy individuals. In Europe, however, hospital outbreaks are rare, but VREF carriage among healthy individuals and livestock is common. We used amplified fragment-length polymorphism analysis to genotype 120 VREF isolates associated with(More)