Global ETD Search

1	Constructing a diffeomorphism between a trimmed domain and the unit square Randrianarivony, Maharavo, Brunnett, Guido, Schneider, Reinhold 31 August 2006 (has links) (PDF) This document has two objectives: decomposition of a given trimmed surface into several four-sided subregions and creation of a diffeomorphism from the unit square onto each subregion. We aim at having a diffeomorphism which is easy and fast to evaluate. Throughout this paper one of our objectives is to keep the shape of the curves delineating the boundaries of the trimmed surfaces unchanged. The approach that is used invokes the use of transfinite interpolations. We will describe an automatic manner to specify internal cubic Bezier-spline curves that are to be subsequently interpolated by a Gordon patch. Some theoretical criterion pertaining to the control points of the internal curves is proposed and proved so as to ensure that the resulting Gordon patch is a diffeomorphism. Numerical results are reported to illustrate the approaches. Our benchmarks include CAD objects which come directly from IGES files. Coons patch Gordon patch surface decomposition trimmed surface ddc:510 CAD Diffeomorphismus IGES
2	Gaminio modelio analizė ir koregavimas pritaikant CAM sistemoms / Model Analysis and Modification for Computer Aided Manufacturing Jankauskas, Kęstutis 29 May 2006 (has links) This research aims at the specifics of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) market. Through discussion of the digital model’s path since geometric construction till completion of a product the major trends are derived. Evolution of hardware for CAM challenges software developers to come up with new solutions. Growing numbers of CAD/CAM software proved to be considerable factor for incompatibility of data formats among systems. Therefore universal data exchange standards were claimed to enable communication. Also a few gaps of functionality among CAD/CAM software products encourages the development of new application, based on research. The set of functions to be integrated into application is supported theoretically according to researched information and tested practically during the realization of software. The most successful standards and tools are selected as the basis of new software. IGES (The Initial Graphics Exchange Specification) standard along with NURBS (Non-Uniform Rational BSpline) curves and surfaces is used for description of geometric data and OpenGL is used as drawing tool. Model analysis and modification for CAM includes following function description and realization: calculation of volume, non-uniform region scaling, 2D packing, curve control point reduction, curve conversion to lines and arcs. Testing results proves that most of the theoretic assumptions are correct and a development of such or similar software is truly... [to full text] Informatics IGES Modelio apdorojimo algoritmai Gaminio modelis Computer Aided Manufacturing NURBS CAM
3	Constructing a diffeomorphism between a trimmed domain and the unit square Randrianarivony, Maharavo, Brunnett, Guido, Schneider, Reinhold 31 August 2006 (has links) This document has two objectives: decomposition of a given trimmed surface into several four-sided subregions and creation of a diffeomorphism from the unit square onto each subregion. We aim at having a diffeomorphism which is easy and fast to evaluate. Throughout this paper one of our objectives is to keep the shape of the curves delineating the boundaries of the trimmed surfaces unchanged. The approach that is used invokes the use of transfinite interpolations. We will describe an automatic manner to specify internal cubic Bezier-spline curves that are to be subsequently interpolated by a Gordon patch. Some theoretical criterion pertaining to the control points of the internal curves is proposed and proved so as to ensure that the resulting Gordon patch is a diffeomorphism. Numerical results are reported to illustrate the approaches. Our benchmarks include CAD objects which come directly from IGES files. info:eu-repo/classification/ddc/510 ddc:510 CAD Diffeomorphismus IGES Coons patch Gordon patch surface decomposition trimmed surface
4	Geometric processing of CAD data and meshes as input of integral equation solvers Randrianarivony, Maharavo 23 November 2006 (has links) (PDF) Among the presently known numerical solvers of integral equations, two main categories of approaches can be traced: mesh-free approaches, mesh-based approaches. We will propose some techniques to process geometric data so that they can be efficiently used in subsequent numerical treatments of integral equations. In order to prepare geometric information so that the above two approaches can be automatically applied, we need the following items: (1) Splitting a given surface into several four-sided patches, (2) Generating a diffeomorphism from the unit square to a foursided patch, (3) Generating a mesh M on a given surface, (4) Patching of a given triangulation. In order to have a splitting, we need to approximate the surfaces first by polygonal regions. We use afterwards quadrangulation techniques by removing quadrilaterals repeatedly. We will generate the diffeomorphisms by means of transfinite interpolations of Coons and Gordon types. The generation of a mesh M from a piecewise Riemannian surface will use some generalized Delaunay techniques in which the mesh size will be determined with the help of the Laplace-Beltrami operator. We will describe our experiences with the IGES format because of two reasons. First, most of our implementations have been done with it. Next, some of the proposed methodologies assume that the curve and surface representations are similar to those of IGES. Patching a mesh consists in approximating or interpolating it by a set of practical surfaces such as B-spline patches. That approach proves useful when we want to utilize a mesh-free integral equation solver but the input geometry is represented as a mesh. Coons Foursided decomposition Mesh-free Quadrangulation Transfinite Interpolation Wavelet-Galerkin ddc:000 ddc:500 B-Spline CAD Diffeomorphismus Gittererzeugung IGES Integralgleichung Mannigfaltigkeit Viereck
5	Flexible Engineering Software: An Integrated Workstation Approach to Finite Element Analysis Ross, Brant Arnold 01 April 1985 (has links) (PDF) One obstacle preventing more engineers from using finite element analysis (FEA) is the difficulty of transferring data between steps in the modeling process. A Fortran computer program, Rosetta.BYU, has been developed to open data paths between finite element preprocessors (mesh generators) and finite element analysis programs, using a custom data structure. It accepts neutral data files, Version 2.0 IGES data files, and Movie.BYU files for input/output. An application of Rosetta is described. A general workstation manager program, Davinci.BYU, is reviewed that provides a support layer between the engineer and the operating system, organizes software and data files, and facilitates on-line documentation and demonstrations. Requirements of a good user interface are discussed and supporting software, Squire.BYU, is described. An application of this software in an industrial setting is described. Flexible Software Engineering Integrated Workstation Finite Element Analysis FEA Data Model Fortran Computer Program Rosetta.BYU Preprocessors Mesh Generators Neutral Version 2.0 IGES Movie.BYU Davinci.BYU Squire.BYU Mechanical Engineering
6	Geometric processing of CAD data and meshes as input of integral equation solvers Randrianarivony, Maharavo 30 September 2006 (has links) Among the presently known numerical solvers of integral equations, two main categories of approaches can be traced: mesh-free approaches, mesh-based approaches. We will propose some techniques to process geometric data so that they can be efficiently used in subsequent numerical treatments of integral equations. In order to prepare geometric information so that the above two approaches can be automatically applied, we need the following items: (1) Splitting a given surface into several four-sided patches, (2) Generating a diffeomorphism from the unit square to a foursided patch, (3) Generating a mesh M on a given surface, (4) Patching of a given triangulation. In order to have a splitting, we need to approximate the surfaces first by polygonal regions. We use afterwards quadrangulation techniques by removing quadrilaterals repeatedly. We will generate the diffeomorphisms by means of transfinite interpolations of Coons and Gordon types. The generation of a mesh M from a piecewise Riemannian surface will use some generalized Delaunay techniques in which the mesh size will be determined with the help of the Laplace-Beltrami operator. We will describe our experiences with the IGES format because of two reasons. First, most of our implementations have been done with it. Next, some of the proposed methodologies assume that the curve and surface representations are similar to those of IGES. Patching a mesh consists in approximating or interpolating it by a set of practical surfaces such as B-spline patches. That approach proves useful when we want to utilize a mesh-free integral equation solver but the input geometry is represented as a mesh. info:eu-repo/classification/ddc/000 ddc:000 info:eu-repo/classification/ddc/500 ddc:500 B-Spline CAD Diffeomorphismus Gittererzeugung IGES Integralgleichung Mannigfaltigkeit Viereck Coons Foursided decomposition Mesh-free Quadrangulation Transfinite Interpolation Wavelet-Galerkin

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