UBC Theses and Dissertations

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UBC Theses and Dissertations

An expert system to diagnose quality problems in the continuous casting of steel billets Kumar, Sunil


Quality problems, such as cracks, rhomboidity and breakouts are often observed in continuously cast steel billets. Although information is available in the literature on the causes of, and solutions to, these problems, the transfer of this knowledge to operating personnel is not always an easy task. To address this issue, an expert system has been developed. The important features of knowledge engineering an expert system to diagnose quality problems in the continuous casting of steel billets are described in this thesis. The process used to extract knowledge from the Experts, the experiments employed to represent knowledge indifferent ways, the strategies adopted to accumulate evidence and the methodologies to present coherent recommendations to both experienced and inexperienced operating personnel are discussed. Expertise was derived from diverse sources. On the one hand fundamental knowledge about heat transfer, solidification and mechanical behaviour of steel was applied to identify the origin of a quality problem in the process; on the other, heuristic knowledge associated with billet characteristics, machine design and operating factors was required to focus on the problem causes. Integration of these two different types of knowledge was essential in developing a useful system. From the Experts' viewpoint, this exercise provided them with a formal representation of their knowledge to solve quality problems and identified new areas for future research. Moreover, the Experts actually generated new ideas about the domain which previously were unrecognized. For the users, this system serves two important functions - as a diagnostic tool for analyzing quality problems and as a teaching tool for new operating personnel.

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