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Geometric Modelling (geometric + modelling)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

Geometry and New and Future Spatial Patterns

ARCHITECTURAL DESIGN, Issue 6 2009
Helmut Pottman
Abstract Despite architects' preoccupation with designing geometric surfaces, there has remained a gap between design and construction. The realisation of complex architectural freeform shapes and the generation of panel patterns continues to be especially challenging, limited by material and manufacturing constraints. Here, Helmut Pottmann, Head of Geometric Modelling and the Industrial Geometry Group within the Institute of Discrete Mathematics and Geometry at Vienna University of Technology (TU Vienna), explores the possibilities thrown up by new research employing fabrication-aware design software. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A pathomechanical concept explains muscle loss and fatty muscular changes following surgical tendon release

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2004
Dominik C. Meyer
Abstract Following tendon tear, the musculo-tendinous unit retracts permanently, looses muscle fibre volume and is infiltrated with fat. This is currently considered to be an unexplained degenerative process. In a sheep model of chronic tendon tear with delayed tendon repair (35 weeks after tendon release), we studied the nature of these muscle changes in eight experimental animals. At sacrifice (75 weeks after tendon release) the muscle had retracted by 1.7±0.5 cm (9% of entire length, P < 0.0001), the pennation angle had increased from 22±2.5° to 50±11° (P < 0.0001) and the mean muscle fibre length had shortened from 32±3 to 16±5 mm (50%, P < 0.0001). In electron and light microscopy, we found essentially normal muscle fibres with an unaltered fibre diameter and myofibrillar structure, while interstitial fat and fibrous tissue had increased from 3.9% to 45.9% (P < 0.0001) of the muscle volume. Geometric modelling showed that the increase of the pennation angle separates the muscle fibre bundles mechanically like limbs of a parallelogram. Infiltrating fat cells fill the created space between the reoriented muscle fibres which may be quantitatively calculated without affecting the structural properties of the muscle cells. Fatty infiltration is therefore not seen as a degenerative process but a necessary rearrangement of the tissue after macroarchitectural changes caused by musculo-tendinous retraction. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]

A survey on Mesh Segmentation Techniques

COMPUTER GRAPHICS FORUM, Issue 6 2008
Ariel Shamir
Abstract We present a review of the state of the art of segmentation and partitioning techniques of boundary meshes. Recently, these have become a part of many mesh and object manipulation algorithms in computer graphics, geometric modelling and computer aided design. We formulate the segmentation problem as an optimization problem and identify two primarily distinct types of mesh segmentation, namely part segmentation and surface-patch segmentation. We classify previous segmentation solutions according to the different segmentation goals, the optimization criteria and features used, and the various algorithmic techniques employed. We also present some generic algorithms for the major segmentation techniques. [source]

Potential field based geometric modelling using the method of fundamental solutions

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2006
Roman Tankelevich
Abstract We propose a new geometric modelling method based on the so-called potential field (PF) modelling technique. The harmonic problem associated with this technique is solved numerically using the method of fundamental solutions (MFS). We investigate the applicability of the proposed approach to parametrically defined curves of varying complexity. Based on the MFS, we also provide definitions of the Boolean operations associated with the geometric modelling. Finally, we give practical applications of the method to computer-aided design and manufacturing problems. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Aspects Regarding the Conception, Modeling and Implementation of an Articulated Robot in Space with Noises and Vibrations

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008
Virgil Ispas
The authors want to conceive and to model a structure of a 6R serial modular industrial robot with six freedom degrees. Some specific points are followed: the direct geometric modelling of the robot using the matrix of rotation method, the given in 3D modelling of the robot, the presentation of its components having some possible applications in the processes of production in the spaces with noises and vibrations. The direct geometrical modelling will be determinate the relative orientation matrices, which express the position of each system Ti, (i=1-6), according to the system Ti,1, also expressing the vectors of relative position of origin Oi of the systems Ti. They will be expressed the orientation of each system Ti in account to the fixed system To attached to the robot base, the set of independent parameters of orientation then are obtained the final equation of the column vector of the generalized coordinates, which express the position and the orientation of the clamping device. The paper presents the two possible applications of the studied robot implementation in a flexible manufacturing cel for the manipulation operations of parts. The robot will be used on the other side for the execution of weld in a points applied to the car carcases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]