Search results for "Triangulation"
showing 10 items of 64 documents
Constructing a Pareto front approximation for decision making
2011
An approach to constructing a Pareto front approximation to computationally expensive multiobjective optimization problems is developed. The approximation is constructed as a sub-complex of a Delaunay triangulation of a finite set of Pareto optimal outcomes to the problem. The approach is based on the concept of inherent nondominance. Rules for checking the inherent nondominance of complexes are developed and applying the rules is demonstrated with examples. The quality of the approximation is quantified with error estimates. Due to its properties, the Pareto front approximation works as a surrogate to the original problem for decision making with interactive methods. Qc 20120127
Skeletizing 3D-Objects by Projections
2004
Skeletization is used to simplify an object and to give an idea of the global shape of an object. This paper concerns the continuous domain. While many methods already exist, they are mostly applied in 2D-space. We present a new method to skeletize the polygonal approximation of a 3D-object, based on projections and 2D-skeletization from binary trees.
Monotonic solution of flow and transport problems in heterogeneous media using Delaunay unstructured triangular meshes
2013
Transport problems occurring in porous media and including convection, diffusion and chemical reactions, can be well represented by systems of Partial Differential Equations. In this paper, a numerical procedure is proposed for the fast and robust solution of flow and transport problems in 2D heterogeneous saturated media. The governing equations are spatially discretized with unstructured triangular meshes that must satisfy the Delaunay condition. The solution of the flow problem is split from the solution of the transport problem and it is obtained with an approach similar to the Mixed Hybrid Finite Elements method, that always guarantees the M-property of the resulting linear system. The…
Variable neighborhood search for the linear ordering problem
2006
Given a matrix of weights, the linear ordering problem (LOP) consists of finding a permutation of the columns and rows in order to maximize the sum of the weights in the upper triangle. This NP-complete problem can also be formulated in terms of graphs, as finding an acyclic tournament with a maximal sum of arc weights in a complete weighted graph. In this paper, we first review the previous methods for the LOP and then propose a heuristic algorithm based on the variable neighborhood search (VNS) methodology. The method combines different neighborhoods for an efficient exploration of the search space. We explore different search strategies and propose a hybrid method in which the VNS is cou…
Towards Technology-Supported Surgical Training
2008
Technology offers alternatives for training surgeons with patients and also possibilities to take part in surgical learning from afar, outside the operating room (OR). Simulated and other technical training tools provide opportunities to practice surgical skills in undisturbed learning environments. In order to implement effective educational methods and create new environments for learning, we need to find out what skills a surgeon must learn and what are the elements affecting surgical performance. This paper describes a study designed to investigate surgical processes and presents an exploratory way of gathering data by combining video material with interviews. The suitability of triangu…
MAST-2D diffusive model for flood prediction on domains with triangular Delaunay unstructured meshes
2011
Abstract A new methodology for the solution of the 2D diffusive shallow water equations over Delaunay unstructured triangular meshes is presented. Before developing the new algorithm, the following question is addressed: it is worth developing and using a simplified shallow water model, when well established algorithms for the solution of the complete one do exist? The governing Partial Differential Equations are discretized using a procedure similar to the linear conforming Finite Element Galerkin scheme, with a different flux formulation and a special flux treatment that requires Delaunay triangulation but entire solution monotonicity. A simple mesh adjustment is suggested, that attains t…
Standard and Z2-Regge theory in two dimensions
1998
Abstract We qualitatively compare two versions of quantum Regge calculus by means of Monte Carlo simulations. In Standard Regge Calculus the quadratic link lengths of the triangulation vary continuously, whereas in the Z2-Regge Model they are restricted to two possible values. The goal is to determine whether the computationally more easily accessible Z2 model retains the characteristics of standard Regge theory.
Monotonic solution of heterogeneous anisotropic diffusion problems
2013
Anisotropic problems arise in various areas of science and engineering, for example groundwater transport and petroleum reservoir simulations. The pure diffusive anisotropic time-dependent transport problem is solved on a finite number of nodes, that are selected inside and on the boundary of the given domain, along with possible internal boundaries connecting some of the nodes. An unstructured triangular mesh, that attains the Generalized Anisotropic Delaunay condition for all the triangle sides, is automatically generated by properly connecting all the nodes, starting from an arbitrary initial one. The control volume of each node is the closed polygon given by the union of the midpoint of…
Place du psychologue en réanimation
2021
Dans les services de soins aigus, comme en réanimation, où l’intégrité physique et psychique des patients est atteinte, le somatique prime mais il est inéluctablement imprégné de la dimension émotionnelle. Les études actuelles témoignent d’ailleurs d’un vécu émotionnel intense et souvent bouleversant, tant pour les patients et leurs proches, que pour les soignants. Le psychologue prend donc place dans cette triangulation patient-famille-soignant afin de préserver la place de la dimension émotionnelle au sein des services de réanimation, et de proposer un accompagnement psychologique adapté. A partir d’un cas clinique, cet article a pour objectif de clarifier, pour les soignants de réanimati…
Symbolic leadership culture and its subcultures in one unified comprehensive school in Finland
2014
Purpose – The purpose of this paper is to describe a symbolic-interpretative research on the leadership culture and its subcultures in one unified comprehensive school in Finland. Design/methodology/approach – The research is a phenomenological, qualitative case study. Its methodology is based on triangulation. Findings – The leadership culture of the unified comprehensive school studied in the present research seemed to be based on equality, communality, appreciation, flow of information and humor. Besides examining the general leadership culture of the school, an attempt was made to study the possible subcultures of the school by examining the six subject groups into which the teachers w…