Predicting category intuitiveness with the rational model, the simplicity model, and the generalized context model.

Na?ve observers typically perceive some groupings for a set of stimuli as more intuitive than others. The problem of predicting category intuitiveness has been historically considered the remit of models of unsupervised categorization. In contrast, this article develops a measure of category intuitiveness from one of the most widely supported models of supervised categorization, the generalized context model (GCM). Considering different category assignments for a set of instances, the authors asked how well the GCM can predict the classification of each instance on the basis of all the other instances. The category assignment that results in the smallest prediction error is interpreted as the most intuitive for the GCM—the authors refer to this way of applying the GCM as “unsupervised GCM.” The authors systematically compared predictions of category intuitiveness from the unsupervised GCM and two models of unsupervised categorization: the simplicity model and the rational model. The unsupervised GCM compared favorably with the simplicity model and the rational model. This success of the unsupervised GCM illustrates that the distinction between supervised and unsupervised categorization may need to be reconsidered. However, no model emerged as clearly superior, indicating that there is more work to be done in understanding and modeling category intuitiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mathematical model of kinetics of filling the model during casting by gasified models

Based on an analysis of the thermal destruction of cellular polystyrene (CPS), an investigation into filling the mold during casting by gasified models is performed. A mathematical model of the process developed on the displacement of gaseous products of the thermal destruction of CPS from the region of gasifying the model by excess pressure in a gas gap between the CPS and liquid metal is made. The results of calculations are compared with the available experimental data on the time dependence of the pressure in the gas gap and measurements of the duration of the pouring time of actual castings. The satisfactory similarity of the calculated dependences and characteristics with experimental ones is shown. The formula for the calculation of the pressure in the thermal destruction region is suggested. This pressure determines the stability of the form and conditions of obtaining suitable castings, as well as the method for calculation of the filling time of the mold.