Hannu T. Toivonen

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Association rules are statements of the form "for 90 % of the rows of the relation, if the row has value 1 in the columns in set X, then it has 1 also in the columns in set Y ". EEcient methods exist for discovering association rules from large collections of data. The number of discovered rules can, however, be so large that the rules cannot be presented(More)
A state-space solutionof the H1 control problem for periodic multirate sampled-data systems is presented. The solution is characterized in terms of a pair of discrete algebraic Riccati equations with a set of associated matrix positive deeniteness conditions and coupling criteria. The solution is derived using two diierent approaches. In the rst approach,(More)
A new discretization based solution to the sampled-data H 1 control problem is given. In contrast to previous solution procedures, the method is not based on the lifting technique. Instead, an equivalent nite-dimensional discrete problem representation is derived directly from a description of the sampled-data system. This is achieved via a closed-loop(More)
A state-space solution to the H 1 control problem for periodic multirate systems is presented. The solution is based on the lifting method, where an equivalent time-invariant system description is derived for the original periodic multirate problem. The H 1-optimal controller for the multirate system is expressed in terms of two algebraic Riccati equations.(More)
A multimodel controller design procedure combined with gain scheduling methods is evaluated for a highly nonlinear chemical process. The controller synthesis method is based on a mixed H 2 /H ∞ problem to achieve good quadratic performance and robustness for a multimodel plant description. The performance obtained with the optimal multimodel controller,(More)