accedaCRIShttps://accedacris.ulpgc.es/jspuiThe accedaCRIS digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 03 Mar 2021 21:38:27 GMT2021-03-03T21:38:27Z5041- Generalized top and bottom binary n-tupleshttp://hdl.handle.net/10553/44519Title: Generalized top and bottom binary n-tuples
Authors: González, L.
Abstract: A complex stochastic Boolean system (CSBS) depends on an arbitrary number n of random Boolean variables. The behavior of a CSBS is determined by the ordering between the occurrence probabilities Pr {u} of the 2 n associated binary strings u ∈ {0, 1} n. In this context, a binary n-tuple is called top (bottom, respectively) if its occurrence probability is always among the 2 n-1largest (smallest, respectively) ones. In this paper we generalize these n-tuples by defining and studying the k-top and k-bottom binary n-tuples, i.e., those whose occurrence probabilities are always among the k largest (smallest, respectively) ones (1 < k < 2 n). These results can be applied to the reliability analysis of many different technical systems, arising from diverse fields of Engineering. © 2008 Civil-Comp Press.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10553/445192008-01-01T00:00:00Z
- An automatic strategy for adaptive tetrahedral mesh generationhttp://hdl.handle.net/10553/45234Title: An automatic strategy for adaptive tetrahedral mesh generation
Authors: Montenegro, R.; Cascón, J. M.; Escobar, J. M.; Rodriguez, E.; Montero, G.
Abstract: This paper introduces a new automatic strategy for adaptive tetrahedral mesh generation. A local refinement/derefinement algorithm for nested triangulations and a simultaneous untangling and smoothing procedure are the main involved techniques. The mesh generator is applied to 3-D complex domains whose boundaries are projectable on external faces of a meccano approximation composed of cuboids. The domain surfaces must be given by a mapping between meccano surfaces and object boundary. This mapping can be defined by analytical or discrete functions. At present, we have fixed mappings with orthogonal, cylindrical and radial projections, but any other one-to-one projection may be considered. The mesh generator starts from a coarse and valid hexahedral mesh that is obtained by an admissible subdivision of the meccano cuboids. The automatic subdivision of each hexahedron into six tetrahedra produces an initial tetrahedral mesh of the meccano approximation. The main idea is to construct a sequence of nested meshes by refining only those tetrahedra with a face on the meccano boundary. The virtual projection of meccano external faces defines a valid triangulation on the domain boundary. Then a 3-D local refinement/derefinement is carried out so that the approximation of domain surfaces verifies a given precision. Once this objective is reached, those nodes placed on the meccano boundary are really projected on their corresponding true boundary, and inner nodes are relocated using a suitable mapping. As the mesh topology is kept during node movement, poor quality or even inverted elements could appear in the resulting mesh; therefore, we finally apply a mesh optimization procedure. The efficiency of the proposed technique is shown with several applications to complex objects.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10553/452342009-01-01T00:00:00Z
- A new meccano technique for adaptive 3-D triangulationshttp://hdl.handle.net/10553/45238Title: A new meccano technique for adaptive 3-D triangulations
Authors: Cascón, J. M.; Montenegro, R.; Escobar, J. M.; Rodriguez, E.; Montero, G.
Abstract: This paper introduces a new automatic strategy for adaptive tetrahedral mesh generation. A local refinement/derefinement algorithm for nested triangulations and a simultaneous untangling and smoothing procedure are the main involved techniques. The mesh generator is applied to 3-D complex domains whose boundaries are projectable on external faces of a coarse object meccano composed of cuboid pieces. The domain surfaces must be given by a mapping between meccano surfaces and object boundary. This mapping can be defined by analytical or discrete functions. At present we have fixed mappings with orthogonal, cylindrical and radial projections, but any other one-to-one projection may be considered. The mesh generator starts from a coarse tetrahedral mesh which is automatically obtained by the subdivision of each hexahedra, of a meccano hexahedral mesh, into six tetrahedra. The main idea is to construct a sequence of nested meshes by refining only those tetrahedra which have a face on the meccano boundary. The virtual projection of meccano external faces defines a valid triangulation on the domain boundary. Then a 3-D local refinement/derefinement is carried out such that the approximation of domain surfaces verifies a given precision. Once this objective is reached, those nodes placed on the meccano boundary are really projected on their corresponding true boundary, and inner nodes are relocated using a suitable mapping. As the mesh topology is kept during node movement, poor quality or even inverted elements could appear in the resulting mesh. For this reason, we finally apply a mesh optimization procedure. The efficiency of the proposed technique is shown with several applications to complex objects.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10553/452382008-01-01T00:00:00Z
- Splitting the unity, bisecting a graph: applications to stochastic Boolean systemshttp://hdl.handle.net/10553/72548Title: Splitting the unity, bisecting a graph: applications to stochastic Boolean systems
Authors: González, Luis
Abstract: This paper deals with the reliability and risk analysis of those complex systems depending on n stochastic Boolean variables. Each one of the 2(n) elementary states associated to such a system is given by its corresponding binary n-tuple of 0s and 1s. A symmetric fractal graph on 2(n) nodes (the so-called intrinsic order graph In) is used for displaying all the binary n-tuples in decreasing order of their occurrence probabilities. The successive bisections of this graph into smaller subgraphs one-to-one correspond to the successive splits of 1 as sum of the occurrence probabilities of those subgraphs. This iterative bisection process satisfies a nice property: if we replace each one of the subgraphs C (obtained after k successive bisections of the original intrinsic order graph I-n) by an unique node weighted by the sum of the probabilities of all vertices lying on C and we sort the new nodes in decreasing order of their weights, then the new condensed graph is exactly the intrinsic order graph I-k. Finally, based on these results, a new algorithm for estimating the unavailability of stochastic Boolean systems is presented.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10553/725482008-01-01T00:00:00Z