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Infinite Cylinder (infinite + cylinder)

Distribution by Scientific Domains
Engineering50%

Selected Abstracts

Adaptive remeshing in large plastic strain with damage

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2005
H. Borouchaki
Abstract The analysis of mechanical structures using the finite element method in the framework of large elasto-plastic strain, needs frequent remeshing of the deformed domain during the computation. Indeed, the remeshing is due to the large geometrical distortion of finite elements and the adaptation to the physical behaviour of the solution as the plastic strain or the damage fields. This paper gives the necessary steps to remesh a mechanical structure during large elasto-plastic deformations with damage. An important part of this process concerns the geometrical and physical error estimates. The proposed method is integrated in a computational environment using the ABAQUS/Explicit solver and the BL2D-V2 adaptive mesher. After recalling the formulation of the elasto-plastic problem with damage, four types of applications using the proposed adaptive remeshing are given: orthogonal cutting, side-pressing of an infinite cylinder, blanking and backward extrusion with drilling. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Multi-dimensional combustion waves for Lewis number close to one

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 3 2007
A. Ducrot
Abstract This paper is devoted to the study of multi-dimensional travelling wave solution for a thermo-diffusive model, describing the propagation of curved flames in an infinite cylinder. The linear dependence of the components of the reaction rate together with the existence of an ignition temperature ensure that the corresponding linearized operator does not satisfy the Fredholm property. A direct consequence is that solvability conditions for the linearized operator are not known and classical methods of nonlinear analysis cannot be directly applied. We prove in this paper existence results of such travelling waves, by first introducing a suitable re-formulation of the equations and then by choosing suitable weighted spaces that allows us to move the essential spectrum away from zero. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Cylindrical metamaterial-based subwavelength antenna

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2009
Aycan Erentok
Abstract A subwavelength monopole antenna radiating in the presence of a truncated cylindrical shell, which has a capped top face and is made of a negative permittivity metamaterial, is analyzed numerically by a method of moments for the volume-surface integral equation on the one hand, and a finite element method on the other hand. It is shown that a center-fed truncated cylinder, in contrast to an infinite cylinder, provides subwavelength resonances, thus suggesting the possibility of having a subwavelength antenna system. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1496,1500, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24386 [source]

Using forward calculations of the magnetic field perturbation due to a realistic vascular model to explore the BOLD effect

NMR IN BIOMEDICINE, Issue 6 2008
José P. Marques
Abstract This paper assesses the reliability of the infinite cylinder model used previously in the literature to simulate blood oxygenation level dependent (BOLD) signal changes. A three-dimensional finite element method was applied to a realistic model of the cortical vasculature, and the results compared with those generated from a simple model of the vasculature as a set of independent, randomly oriented, infinite cylinders. The realistic model is based on scanning electron microscopy measurements of the terminal vascular bed in the superficial cortex of the rat. Good agreement is found between the two models with regard to the extravascular R2* and R2 dependence on the cerebral blood volume and blood oxygenation fraction. Using the realistic model, it is also possible to gain further understanding of the relative importance of intravascular and extravascular BOLD contrast. A simple parameterisation of the dependence of the relaxation rates on relative cerebral blood volume and blood,tissue susceptibility difference was carried out, allowing discussion of the variation in the form of the haemodynamic response with field strength. Copyright © 2007 John Wiley & Sons, Ltd. [source]