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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

CSG solid modelling and automatic NC machining of blend surfaces

Zhang, Dayong January 1986 (has links)
No description available.
2

Influence of frequency, stress ratio and stress state on fatigue crack growth in nickel base superalloys at elevated temperature

Ventura Antunes, Fernando Jorge January 1999 (has links)
No description available.
3

Parameterized Shape Grammar for n-fold Generating Islamic Geometric Motifs

Sayed, Zahra, Ugail, Hassan, Palmer, Ian J., Purdy, J., Reeve, Carlton January 2015 (has links)
No / The complex formation of Islamic geometric Patterns (IGP) is one of the distinctive features in Islamic art and architecture. Many have attempted to reproduce these patterns in digital form, using various pattern generation techniques. Shape grammars are an effective pattern generation method, providing good aesthetic results. In this paper we present a novel approach in generating 3D IGP using an extended shape grammar: Parametrized Shape Grammar (PSG). PSG allows a user to generate both original and novel forms of Islamic geometric motifs (a repeated unit of a pattern). PSG is generalized to generate n-fold Islamic geometric motifs in a 3D environment, practically implemented as a 3D modeling tool within Autodesk Maya. The parametrization within each grammar rule is the key to generating numerous original and novel Islamic geometric motifs.
4

Partial differential equations for function based geometry modelling within visual cyberworlds

Ugail, Hassan, Sourin, A. January 2008 (has links)
We propose the use of Partial Differential Equations (PDEs) for shape modelling within visual cyberworlds. PDEs, especially those that are elliptic in nature, enable surface modelling to be defined as boundary-value problems. Here we show how the PDE based on the Biharmonic equation subject to suitable boundary conditions can be used for shape modelling within visual cyberworlds. We discuss an analytic solution formulation for the Biharmonic equation which allows us to define a function based geometry whereby the resulting geometry can be visualised efficiently at arbitrary levels of shape resolutions. In particular, we discuss how function based PDE surfaces can be readily integrated within VRML and X3D environments
5

Towards a definition of virtual objects with Partial Differential Equations

Ugail, Hassan, Sourin, A., Sourina, O., Gonzalez Castro, Gabriela January 2009 (has links)
No / We propose an efficient alternative to commonly used parametric surfaces such as NURBS surfaces for definition of complex geometry in shared virtual spaces. Our mathematical model allows to define objects by only providing coordinates of the section curves in 3-space. The resulting parametric functions allow fast calculation of the coordinates of the points on the surface of the objects. We devise an algorithm which evaluates the coefficients of these functions in real time. Given the small size of the resulting formulas and interactive rates for their calculation, we are able to efficiently use such PDE-based models for making virtual objects in shared virtual spaces. We describe the modeling framework and illustrate the proposed theoretical concepts with our function-based extension of VRML and X3D.
6

Automatic segmentation and analysis of Magnetic Resonance images of the knee bones and cartilages

Mr Jurgen Fripp Unknown Date (has links)
No description available.
7

Modelling the mechanical behaviour of a pharmaceutical tablet using PDEs

Ahmat, Norhayati, Ugail, Hassan, Gonzalez Castro, Gabriela 01 1900 (has links)
yes / Detailed design of pharmaceutical tablets is essential nowadays in order to produce robust tablets with tailor-made properties. Compressibility and compactibility are the main compaction properties involved in the design and development of solid dosage forms. The data obtained from measured forces and displacements of the punch are normally analysed using the Heckel model to assess the mechanical behaviour of pharmaceutical powders. In this paper, we present a technique for shape modelling of pharmaceutical tablets based on the PDE method. We extended the formulation of the PDE method to a higher dimensional space in order to generate a solid tablet and a cuboid mesh is created to represent the tablet’s components. We also modelled the displacement components of a compressed PDE-based representation of a tablet by utilising the solution of the axisymmetric boundary value problem for a finite cylinder subject to a uniform axial load. The experimental data and the results obtained from the developed model are shown in Heckel plots and a good agreement is found between both. / Available in full text since 5th Feb 2013 following the publisher's embargo period.
8

Auto-Parameterized Shape Grammar for Constructing Islamic Geometric Motif-Based Structures

Sayed, Zahra, Ugail, Hassan, Palmer, Ian J., Purdy, J., Reeve, Carlton 29 June 2016 (has links)
Yes / The complex formation of Islamic Geometric Patterns (IGP) is one of the distinctive features in Islamic art and architecture. Many have attempted to reproduce these patterns in digital form, using various pattern generation techniques, in 2D. Shape grammars are an e ective pattern generation method, providing good aesthetic results. In this pa- per we describe a novel approach in generating 3D IGP using the shape grammar method. The particular emphasis here is to generate the motifs (repeated units with the pattern) in 3D using parameterization. These can then be manipulated within the 3D space to construct architec- tural structures. In this work we have developed two distinctive Shape Grammars in 3D namely Parameterized Shape Grammar (PSG) and Auto-Parameterized Shape Grammar (APSG). Here the PSG generates the motifs and the APSG enables construction of the structures using the generated motifs. Both grammars are practically implemented as a 3D modelling tool within Autodesk Maya. The parameterization within each grammar is the key to generate both Islamic geometric motifs and Islamic geometric motif-based structures.

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