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The Global ETD Search service is a free service for researchers
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Showing 1 to 5 of 5 (0.151 seconds)Spelling suggestions: "subject:"parametric representation"" "subject:"arametric representation""
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Interactive design of complex mechanical parts using a parametric representationUgail, Hassan, Robinson, M., Bloor, M.I.G., Wilson, M.J. January 2000 (has links)
Yes / In CAD, when considering the question of new designs of complex mechanical parts, such as engine pistons, a parametric representation of the design is usually defined. However, in general there is a lack of efficient tools to create and manipulate such parametrically defined shapes.
In this paper, we show how the geometry of complex mechanical parts can be parameterised efficiently enabling a designer to create and manipulate such geometries within an interactive environment. For surface generation we use the PDE method which allows surfaces to be defined in terms of a relatively small number of design parameters. The PDE method effectively creates surfaces by using the information contained at the boundaries (edges) of the surface patch. An interactively defined parameterisation can then be introduced on the boundaries (which are defined by means of space curves) of the surface. Thus, we show how complex geometries of mechanical parts, such as engine pistons, can be efficiently parameterised for geometry manipulation allowing a designer to create alternative designs.
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Loewner Theory in Several Complex Variables and Related ProblemsVoda, Mircea Iulian 11 January 2012 (has links)
The first part of the thesis deals with aspects of Loewner theory in several complex variables.
First we show that a Loewner chain with minimal regularity assumptions (Df(0,t) of local bounded variation) satisfies an associated Loewner equation. Next we give a way of renormalizing a general Loewner chain so that it corresponds to the same increasing family of domains. To do this
we will prove a generalization of the converse of Carathéodory's kernel convergence theorem.
Next we address the problem of finding a Loewner chain solution to a given Loewner chain equation.
The main result is a complete solution in the case when the infinitesimal generator satisfies Dh(0,t)=A where inf {Re<Az,z>: ||z| =1}> 0. We will see that the existence of a bounded solution depends on the real resonances of A, but there always exists a polynomially bounded solution.
Finally we discuss some properties of classes of biholomorphic mappings associated to A-normalized Loewner chains. In particular we give a characterization of the compactness of the class of spirallike
mappings in terms of the resonance of A.
The second part of the thesis deals with the problem of finding examples of extreme points for some
classes of mappings. We see that straightforward generalizations of one dimensional extreme functions give examples of extreme Carathéodory mappings and extreme starlike mappings on the polydisc, but not on the ball. We also find examples of extreme Carathéodory mappings on the ball
starting from a known example of extreme Carathéodory function in higher dimensions.
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Loewner Theory in Several Complex Variables and Related ProblemsVoda, Mircea Iulian 11 January 2012 (has links)
The first part of the thesis deals with aspects of Loewner theory in several complex variables.
First we show that a Loewner chain with minimal regularity assumptions (Df(0,t) of local bounded variation) satisfies an associated Loewner equation. Next we give a way of renormalizing a general Loewner chain so that it corresponds to the same increasing family of domains. To do this
we will prove a generalization of the converse of Carathéodory's kernel convergence theorem.
Next we address the problem of finding a Loewner chain solution to a given Loewner chain equation.
The main result is a complete solution in the case when the infinitesimal generator satisfies Dh(0,t)=A where inf {Re<Az,z>: ||z| =1}> 0. We will see that the existence of a bounded solution depends on the real resonances of A, but there always exists a polynomially bounded solution.
Finally we discuss some properties of classes of biholomorphic mappings associated to A-normalized Loewner chains. In particular we give a characterization of the compactness of the class of spirallike
mappings in terms of the resonance of A.
The second part of the thesis deals with the problem of finding examples of extreme points for some
classes of mappings. We see that straightforward generalizations of one dimensional extreme functions give examples of extreme Carathéodory mappings and extreme starlike mappings on the polydisc, but not on the ball. We also find examples of extreme Carathéodory mappings on the ball
starting from a known example of extreme Carathéodory function in higher dimensions.
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Using a Catenary Equation in Parametric Representation for Minimizing Stress Concentrations at Notches / Minimierung der Spannungskonzentration an Kerben mittels einer Kettenlinie in parametrischer DarstellungJakel, Roland 26 June 2015 (has links) (PDF)
Der Vortrag beschreibt, wie sich mittels Kettenlinien als Kerbgeometrie der Spannungskonzentrationsfaktor an Querschnittsübergängen auf nahezu 1 reduzieren lässt. Mittels globaler Sensitivitätsstudien in der p-FEM-Software Creo Simulate wird mithilfe eines in Creo Parametric parametrisierten CAD-Modells der Kettenlinie in Parameterdarstellung ein normiertes Kerbzahldiagramm erstellt. Dieses erlaubt die Dimensionierung einer Kerbe, d.h. die Festlegung ihrer exakten Geometrie und der damit verbundenen Kerbzahl αk ohne die weitere Verwendung eines FEM-Programmes. / The presentation describes how to reduce the stress concentration factor at cross section transitions to nearly 1 by using a catenary curve as notch geometry (catenary fillet). With help of global sensitivity studies performed in the p-FEM-code Creo Simulate, a normalized stress concentration factor diagram is drawn. Therefore, a CAD-model of the catenary curve in parametric representation was developed. The diagram created allows to dimension the notch, that means to determine its exact geometry and stress concentration factor Kt, without further usage of a FEM code.
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Using a Catenary Equation in Parametric Representation for Minimizing Stress Concentrations at NotchesJakel, Roland 26 June 2015 (has links)
Der Vortrag beschreibt, wie sich mittels Kettenlinien als Kerbgeometrie der Spannungskonzentrationsfaktor an Querschnittsübergängen auf nahezu 1 reduzieren lässt. Mittels globaler Sensitivitätsstudien in der p-FEM-Software Creo Simulate wird mithilfe eines in Creo Parametric parametrisierten CAD-Modells der Kettenlinie in Parameterdarstellung ein normiertes Kerbzahldiagramm erstellt. Dieses erlaubt die Dimensionierung einer Kerbe, d.h. die Festlegung ihrer exakten Geometrie und der damit verbundenen Kerbzahl αk ohne die weitere Verwendung eines FEM-Programmes. / The presentation describes how to reduce the stress concentration factor at cross section transitions to nearly 1 by using a catenary curve as notch geometry (catenary fillet). With help of global sensitivity studies performed in the p-FEM-code Creo Simulate, a normalized stress concentration factor diagram is drawn. Therefore, a CAD-model of the catenary curve in parametric representation was developed. The diagram created allows to dimension the notch, that means to determine its exact geometry and stress concentration factor Kt, without further usage of a FEM code.
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