The knowledge-based pattern recognition (KE) approach provides a basis for classification of state of fluid systems. The new method determines bubble size distribution at high pressure that is very important for the brewery industry and other alcoholic beverages (champagne). Conforming to the principle of "decreasing precision with increasing intelligence", the KE approach has been applied to the determination of bubble size distribution. An important feature of these architectures is that they do not require global mathematical modeling of the system. (c) 2005 Elsevier B.V. All rights reserved.