The paper deals with application of the ortho-diagonal (O-D) method of finding the nondominated sets of solutions and evaluations for discrete polyoptimization problems. First, the (O-D) method was modified for finding minimum of a scalar function. The monotonicity property of a vector objective function is used by the (O-D) method for consecutive finding of j-th-criteria partial nondominated sets,

W. Moczulski. Methodology of knowledge acquisition for machinery diagnostics. CAMES 1999 (6)

The paper deals with a comprehensive methodology concerning knowledge acquisition on machinery for the purpose of expert systems suitable for aiding of diagnostic inference. The methodology includes selected methods of diagnostic knowledge representation, methods of knowledge acquisition from domain experts and from preclassified examples, methods of assessment of previously acquired knowledge and a scenario of knowledge acquisition process. All the methods have been implemented in a Knowledge Acquisition System. Moreover, some examples of applications of the elaborated methodology have been given.
*Keywords:* machinery diagnostics, knowledge acquisition, domain experts, machine learning, assessment of knowledge.

Z. Waszczyszyn and E. Pabisek. Hybrid NN/FEM analysis of the elastoplastic plane stress problem. CAMES 1999 (6)

The back-propagation neural network was trained off line in order to simulate operation of the return mapping algorithm. Selection of patterns and the neural network training as well as testing processes are discussed in detail. The network was incorporated into the FE computer code ANKA as a neural procedure. The hybrid neural-network/finite-element-method program ANKA-H was used for the analysis of two elastoplastic plane stress examples: i) perforated tension strip, ii) notched beam. The results of computations point out quite good accuracy of the hybrid analysis. Some prospects of development of hybrid NN/FEM programs are given at the end of paper.

P. Tauzowski and M. Kleiber. Parameter sensitivity formulation for viscoelastic structures. CAMES 1999 (6)

The problem of sensitivity of viscoelastic response with respect to material parameters is studied in the paper. The direct differentiation method is employed. The FEM-related implementation issues are discussed. A number of numerical examples illustrates the theory.

F.Z. Wilke and J.B.S. de Oliveira. Estimating the error of coordinate measuring machines. CAMES 1999 (6)

This paper presents a strategy to analyze the accuracy of measurements obtained in the calibration process of a Coordinate Measuring Machine (CMM). Thereafter, the operator will be able to find the most appropriate placement region for a part to be analyzed in order to reduce the error and take into account the shape of each part. Such strategy was developed through the visualization of error contours in the measurement space. Five different error indexes were developed for this analysis, associating different values to each point of the measurement space, allowing the user to choose the aspect he wants to take into consideration in the measurement process: centering of samples, dispersion, average errors, and others. Finally, the results are transformed into images, analysed and compared.

W. Szemplinska-Stupnicka, E. Tyrkiel and A. Zubrzycki Chaotic oscillations in a model of suspended elastic cable under planar excitation. CAMES 1999 (6)

The single mode equation of motion of a suspended elastic cable under planar excitation is considered, and numerical exploration is focused on the chaotic oscillations which occur in a certain domain of system control parameters. Bifurcations of the subharmonic resonance oscillation and their evolution into chaotic attractor are studied. Then the global bifurcation theory is applied to determine the critical system parameters for which the chaotic attractor undergoes the subduction destruction in the "boundary crisis'' scenario. The post-crisis transient motion, which in this case becomes the generic long-lasting chaotic system response, is also studied.

K. Cichocki, R. Adamczyk and M. Ruchwa. Material modelling for structures subjected to impulsive loading. CAMES 1999 (6)

The main results of numerical analyses of a possible design configuration of a submerged structure subjected to impulsive loading due to explosion, performed for various material models assumed for a plain concrete are presented and discussed. Three different models were considered - the modified Drucker-Prager plasticity model, brittle cracking model and the elastoplastic model with damage. The present study suggests problems and possible solutions to be applied into numerical analysis of such structures by means of available finite element computer codes.