The effects of feature frequency and similarity on object recognition have been examined through behavioral experiments, and a model of the formation of visual object representations and old/new recognition has been proposed. A number of experiments were conducted to test the hypothesis that frequency and similarity of object features affect the old/new responses to test stimuli in a later recognition task. In the first experiment, when the feature frequencies are controlled, there was a significant increase in the percentage of &ldquo / old&rdquo / responses for unstudied objects as the number of frequently repeated features (FRFs) on the object increased. In the second experiment, where all features had equal frequency, similarity of test objects did not affect old/new responses. An evaluation of the models on object recognition and categorization with respect to the experimental results showed that these models can only partially explain experimental results. A comprehensive model for the formation of visual object representations and old/new recognition, called CDZ-VIS, developed on the Convergence-Divergence Zone framework by Damasio (1989), has been proposed. According to this framework, co-occurring object features converge to upper layer units in the hierarchical representation which act as binding units. As more objects are displayed, frequent object features cause grouping of these binding units which converge to upper binding units. The performance of the CDZ-VIS model on the feature frequency and similarity experiments of the present study was shown to be closer to the performance of the human participants, compared to the performance of two models from the categorization literature.

During the conceptual design stage several concepts are generated, and a few are selected for detailed analyses. CAD models from conceptual design often follow the "over-the-wall" approach for downstream analyses such as FEA, CFD, heat transfer, and vibrations. A CAD-centric approach will be applied to the CAD-to-CFD process to help industry in an ongoing quest to shorten the design cycle time. The CAD-centric approach consists of using the CAD model as a source of data for downstream applications such as mesh generation, and CFD setup. The CAD model used in the CAD-centric approach contains the geometry to be analyzed and non-geometric data required to solve the CFD problem in the form of attributes. Attributes can be associated to entities of the geometry such as the faces, edges, and volumes. Any operations changing geometry require the CAD-centric model be reworked. One class of topology alterations is the discrete feature problem that is encountered when an array of features change in number. A method is proposed, developed and reported on that adapts the CAD-centric approach to account for discrete feature changes that occur during preliminary design.