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Browsing by Author "Gandhi, Ashit R."

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    A CAD/CAM interface for computer-aided design of cams
    Gandhi, Ashit R. (Virginia Tech, 1985-12-15)
    The purpose of this thesis is to provide a complete package for the design and three dimensional modeling display of cams. The software produced as a part of this work will operate as a module of CADAM to produce cam designs and enter the resulting cam as a CAD model and produce the graphical display of the cam. In addition to the introductory material, this thesis is divided into four sections. The section on the graphics packages used in this thesis includes a brief history and capabilities of each of the packages. The second section details the procedure to be adopted in order to design a cam. The next section details ANICAM, the program that has been developed to incorporate the design and display procedure. The fourth section of this thesis contains recommendations for further work in this area. The theoretical work in this project is a combination of original derivations and applications of the theory in the design literature.
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    Feature-based geometric modeling using B-spline surfaces and a natural language approach
    Gandhi, Ashit R. (Virginia Polytechnic Institute and State University, 1989)
    Traditionally, design geometries are represented using orthographic views which require a human being to interpret them and recognize geometric features to evaluate the design. Solid modeling systems have made the task somewhat easier, but they often require tedious and complex operations using simple geometric primitives. This has led to investigation of modeling systems which allow the creation of assemblies the way engineers conceive them - as features. To be able to efficiently describe models in terms of features, a rich set of feature descriptors are necessary. An exhaustive study of English words describing form, shape, feature, shape altering transformations and surface conditions was done to establish a wide vocabulary for feature based description. Classification based on topology and form was done and prototype constraint relations were implemented to differentiate between some features. A feature is created from a topological group by computing points and interpolating them with uniform rational B-spline patches. Control points needed to compute the patches are computed from the interpolation points by an inverse relation. A designer-oriented modeling language, based on simple English syntax, was devised to specify procedures to be executed by the modeler in order to create features using minimal user input.