Computers them. Engng Vol. 19, Suppl., pp. S821-S826,1995 Copyright 0 1995 Elsevier Science Ltd zyxwvutsrqpo 009%1354(95)OOll7-4 Printed in Great Britain. All rights reserved 0098-1354/95 $9.50 + 0.00 CASEBASED REASONING SYSTEM FOR MIXING EQUIPMENT SELECTION A. Kraslawski, T. Koiranen, L. Nystrom Lappeenranta University of Technology Department of Chemical Technology, P.O.Box 20, FIN-53851 Lappeenranta, Finland ABSTRACT Case-based reasoning (CBR) is an alternative approach to rule-based and object-oriented systems. CBR is based on the retrieval and adaptation of the old solutions to the new problems. There are five steps in CBR: presentation of a new problem, retrieval of the most similar cases, adaptation of the most similar old solutions, validation of the current solution and updating of the system by adding the verified solution to the database of cases. The main advantages of CBR are the easy knowledge acquisition and simple explanatory system. Other important features are easy maintenance and learning capabilities. Determination of the most important features in mixing equipment selection and their importance is studied in this work. The main features discussed are liquid volume and rheological parameters, content of particles and/or gas bubbles as well as the type of application and the aim of the process. The retrieval search has been organized by using flat memory and serial search. The following data are given as the output values of the system: impeller and entering type, scale of agitation, mixing power, number of impellers and geometry of tank. An example of CBR applications to the mixing equipment selection in wastewater industry is given. KEYWORDS Case-based reasoning, knowledge-based systems, mixing equipment, wastewater treatment, INTRODUCTION The most common forms of knowledge-based tools are rule-based and object oriented systems. However there are several difficulties with the real-world applications of both techniques, Vargas and Raj (1993). They are following problems in rule-based systems (RBS). The experts present their knowledge in the form of examples. It is a difficult and S821