Wyniki wyszukiwania - BazTech

1

Improved GETMe by adaptive mesh smoothing

Vartziotis D., Papadrakakis M.

Computer Assisted Methods in Engineering and Science

|

2013

|

Vol. 20, no. 1

55--71

EN

Mesh smoothing improves mesh quality by node relocation without altering mesh topology. Such methods play a vital role in finite element mesh improvement with a direct consequence on the quality of the discretized solution. In this work, an improved version of the recently proposed geometric element transformation method (GETMe) for mesh smoothing is presented. Key feature is the introduction of adaptive concepts, which improve the resulting mesh quality, reduce the number of parameters, and enhance the parallelization capabilities. Implementational aspects are discussed and results of a more efficient version are presented, which demonstrate that GETMe adaptive smoothing yields high quality meshes, is particularly fast, and has a comparably low memory profile. Furthermore, results are compared to those of other state-of-the-art smoothing methods.

2

The efficiency of the application of the heap lists to the algorithm of mesh generation

Kucwaj J.

Computer Assisted Mechanics and Engineering Sciences

|

2010

|

Vol. 17, no. 2-3-4

137-145

EN

The paper presents an analysis of the efficiency of the application of heap lists data structures to the 2D triangular mesh generation algorithms. Such efficiency is especially important for the frontal methods for which the size of the generated mesh is controlled by a prescribed function in the considered domain. In the presented approach two advancing front procedures are presented: first for points insertion and the second for the Delaunay triangulation. If the heap lists are applied to the minimal size of frontal segment selection, a better quality mesh is obtained.

3

Numerical investigations of the convergence of a remeshing algorithm on an example of subsonic flow

Kucwaj J.

Computer Assisted Mechanics and Engineering Sciences

|

2010

|

Vol. 17, no. 2-3-4

149-160

EN

The main goal of the paper is to analyze convergence of a remeshing scheme evaluated by the author [8] on the example of a potential flow around a profile. It is assumed that flow is stationary, irrotational, inviscid and compressible. The problem is led to solving nonlinear differential equation with additional nonlinear algebraic equation representing the so called Kutta-Joukovsky condition. For adaptation a remeshing scheme is applied. For every adaptation step mesh is generated using grid generator [7], which generates meshes with mesh size function. The mesh size function is modified at every adaptation step by nodal values of the error indicator interpolation. The nonlinear algebraic system of equations obtained from discretizing of the problem, is solved by the application of the Newton-Raphson method.

4

On the application of content adaptive mesh image representation

Chlewicki W., Rogala T.

Pomiary Automatyka Kontrola

|

2006

|

R. 52, nr 9

52-54

EN

In this article we focus on image representation using Content Adaptive Mesh Models (CAMM). We discuss the idea of image representation using the triangular mesh and limitations of this method. The performance of the methods is evaluated with two sample images representative for biomedical applications: brain reconstruction from Positron Emission Tomography (PET) scanner and Shepp-Logan head phantom. The conclusion is that the CAMM approach may be very effective representation for image reconstruction, but the current version of the algorithm is inappropriate for very low contrast data, such as the Shepp-Logan phantom. The main conclusion is that the node placement scheme should be corrected to prevent excess concentration of nodes in unimportant regions of highcontrast and shortage of nodes in low-contrast parts of the image. It is postulated that contrast stretching could be a possible solution to that limitation.

PL

W artykule opisano zastosowanie reprezentacji obrazu w postaci adaptujacej się do jego zawartości siatki elementów trójkatnych (ang. Content Adaptive Mesh Models - CAMM). Przeanalizowano skuteczność takiego podejścia i ograniczenia metody na przykładzie dwóch obrazów testowych, typowych dla zastosowań biomedycznych: rekonstrukcji skanu mózgu z wykorzystaniem tomografii emisyjnej (PET) oraz tzw. fantomu Sheppa-Logana. Na podstawie uzyskanych wyników wnioskuje się, że wykorzystanie siatki elementów trójkatnych może być bardzo efektywnym sposobem reprezentacji obrazu, jednak w swojej obecnej wersji algorytm nie sprawdza się w przypadkach w których część obrazu cechuje sie niskim kontrastem. Zasugerowano zastosowanie kompresji kontrastu w celu przezwyciężenia tego ograniczenia.

5

Definition and interpolation of discrete metric for mesh generation on 3D surfaces

Głut B., Jurczyk T.

Computer Science

|

2005

|

Vol. 7

89-103

EN

The article concerns the problem of a definition of the control space from a set of discrete data (metric description gathered from different sources) and its influence on the efficiency of the generation process with respect to 2D and 3D surface meshes. Several methods of metric interpolation between these discrete points are inspected, including an automated selection of proper method. Some aspects of the procedures of creation and employment of the mesh control space based on the discrete set of points are presented. The results of using different variations of these methods are also included.

PL

Artykuł opisuje zagadnienie definicji przestrzeni kontrolnej (sterującej procesem generowania siatek) na podstawie dyskretnych danych (opisu metryki pozyskanego z różnych zródeł) oraz jej wpływu na wydajność procesu generacji siatek na płaszczyźnie oraz powierzchniach trójwymiarowych. Rozpatrywane są różne metody interpolacji metryki w obszarach pomiędzy dyskretnymi punktami ze zdefiniowaną metryką, włącznie z automatyczną metodą wyboru odpowiedniej metody interpolacji. Przedstawione są zagadnienia związane z procesem tworzenia i wykorzystywania przestrzeni kontrolnej opartej na informacji z dyskretnego zbioru punktów. Załączone są także przykładowe wyniki zastosowania różnych wariantów opisywanych metod.