J.L. Top

Tasks and ontologies in engineering modelling

Constructing models of physical systems is a recurring activity in engineering problem solving. This paper presents a generic knowledge-level analysis of the task of engineering modelling. Starting from the premise that modelling is a design-like activity, it proposes the Specify-Construct-Assess (SCA) problem-solving method for decomposition of the modelling task. A second structuring principle is found in the distinction between and separation of different ontological viewpoints. Here, we introduce three engineering ontologies that have their own specific roles and methods in the modelling task: functional components, physical processes, mathematical constraints. The combination of the proposed task and ontology decompositions leads to a particular approach to modelling that we call evolutionary modelling. This approach is supported by a knowledge-based system called QuBA. The implications of evolutionary modelling for structuring the modelling process, the content of produced models, as well as for the organization of reusable model fragment libraries are discussed.

Reusability of simulation models

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 generally important in physical systems engineering. In addition, the paper suggests that such libraries need to support various kinds of modelling assumptions about model fragments. Modelling can be usefully approached as a form of assumption management, as a means of reflecting the metalevel knowledge that is employed by experienced engineers. A categorization of modelling assumptions is proposed that aims at further support for reusability and shareability.

Automatic revision of simulation models

We have developed 007, an intelligent modeling assistant that assists a human modeler in three main revision tasks: (i) representation of the physical models, (ii) clarification of goals and formulation of explicit requirements, and (iii) modification of the physical model. 007 helps users to formulate explicit, testable requirements and to assess the current model. It then executes generic repair plans and revises the model until the requirements are met.