Search results for "Matemàtica aplicada"
showing 10 items of 10 documents
High order finite difference schemes for hyperbolic conservation laws on complex domains: extrapolation and time integration techniques
2016
Els esquemes d’alta resolució de tipus shock capturing s’empren àmpliament en el càlcul d’aproximacions numèriques precises de la solució de molts sistemes de lleis de conservació hiperbòliques, especialment en dinàmica computacional de fluids. En aquest context, l’aplicació de condicions de frontera adequades en dominis amb geometria complexa s’ha convertit en un problema amb una certa dificultat que s’ha abordat de diferents maneres segons la naturalesa dels mètodes numèrics i del tipus de malla. En aquest treball presentem una tècnica d’extrapolació d’informació a partir de l’interior del domini computacional a cel·les fantasma destinada a malles cartesianes estructurades (les quals, a d…
A Model for Developing an Academic Activity Index for Higher Education Instructors Based on Composite Indicators
2020
The assessment of the teacher performance is a subject of criticism due to the lack of a well-establish methodology. This study develops an overall score to measure the dimensions that encompass the academic activities. To that end, a Benefit-of-the-doubt model is proposed. The advantage of this technique is the flexibility in the weights, so that the model selects for each teacher the most favourable set of weights. Furthermore, the paper proposes the barycentric coordinate system as a method to classify the teachers in clusters depending on their contribution to the dimensions. A specific pie chart has been proposed as an efficient way to report the contribution of the teachers to the di…
A question from the Kourovka Notebook on formation products
2003
[EN] It is shown in this paper that if X is a class of simple groups such that pi(X) = char X, the X-saturated formation H generated by a finite group cannot be expressed as the Gaschütz product F o G of two non-X-saturated formations if H = G. It answers some open questions on products of formations. The relation between omega-saturated and X-saturated formations is also discussed.
Suma
2006
En estas últimas décadas la gestión de las actividades relacionadas con el deporte ha tomado un papel relevante para las instituciones deportivas. La matemática borrosa, aporta un conjunto de algoritmos que permiten establecer la idoneidad del deportista, el cual ha de reunir ciertas cualidades que lo hagan adecuado para la posición o posiciones que debe ocupar en un determinado equipo. Bajo estos preceptos, hay que resaltar que la Teoría de Conjuntos Borrosos no es un segmento de la Matemática emergente en nuestros días si no que, tiene sus inicios en la década de los años 20, siendo en la de los 50, donde sentó sus bases.
A level set method with Sobolev Gradient and Haralick Edge Detection
2014
Variational level set methods, which have been proposed with various energy functionals, mostly use the ordinary L type gradient in gradient descent algorithm to minimize the energy functional. The gradient flow is influenced by both the energy to be minimized and the norms, which are induced from inner products, used to measure the cost of perturbation of the curve. However, there are many undesired properties related to the gradient flows due to the 2 L type inner products. For example, there is not any regularity term in the definition of this inner product that causes non-smooth flows and inaccurate results. Therefore, in this work, Sobolev gradient has been used that is more efficient …
Preferencias entre unidades eficientes : una aplicación de supereficiencia fuzzy basada en niveles de exigencias
2014
En el contexto económico actual, lograr el máximo de eficiencia es una cuestión clave para las empresas. En ocasiones, los métodos clásicos de análisis de la eficiencia, como el Data Envelopment Analysis (DEA), no ofrecen al empresario información suficiente al clasificar las unidades de decisíon en dos grupos, las eficientes y las ineficientes. Los gestores demandan más información sobre la eficiencia de su empresa, de modo que la puedan comparar con la del resto de firmas y conocer su posición relativa dentro del grupo de empresas eficientes o ineficientes. En este trabajo se propone un enfoque, basado en la lógica fuzzy, que completa los modelos DEA clásicos y permite, a partir de los mo…
Algorithms for solving the inverse problem associated with KAK =A^(s+1)
2017
In previous papers, the authors introduced and characterized a class of matrices called {K,s+1}-potent. Also, they established a method to construct these matrices. The purpose of this paper is to solve the associated inverse problem. Several algorithms are developed in order to find all involutory matrices K satisfying K A^(s+1) K = A for a given matrix A∈C^(n×n) and a given natural number s. The cases s=0 and s≥ are separately studied since they produce different situations. In addition, some examples are presented showing the numerical performance of the methods.
Algorithms for {K, s+1}-potent matrix constructions
2013
In this paper, we deal with {K, s + 1}-potent matrices. These matrices generalize all the following classes of matrices: k-potent matrices, periodic matrices, idempotent matrices, involutory matrices, centrosymmetric matrices, mirrorsymmetric matrices, circulant matrices, among others. Several applications of these classes of matrices can be found in the literature. We develop algorithms in order to compute {K, s + 1}-potent matrices and {K, s + 1}-potent linear combinations of {K, s + 1}-potent matrices. In addition, some examples are presented in order to show the numerical performance of the method. (C) 2012 Elsevier B.V. All rights reserved.
On the equivalence between the Scheduled Relaxation Jacobi method and Richardson's non-stationary method
2017
The Scheduled Relaxation Jacobi (SRJ) method is an extension of the classical Jacobi iterative method to solve linear systems of equations ($Au=b$) associated with elliptic problems. It inherits its robustness and accelerates its convergence rate computing a set of $P$ relaxation factors that result from a minimization problem. In a typical SRJ scheme, the former set of factors is employed in cycles of $M$ consecutive iterations until a prescribed tolerance is reached. We present the analytic form for the optimal set of relaxation factors for the case in which all of them are different, and find that the resulting algorithm is equivalent to a non-stationary generalized Richardson's method. …
An evaluation of the environmental factors for supply chain strategy decisions using grey systems and composite indicators
2020
[EN] The purpose of this work is to assess the importance of environmental factors in a supply chain with four partners as a preliminary step to select the competitive strategies and objectives. To achieve this purpose, a real case study was carried out in a footwear supply chain, in which two approaches were used: the grey system theory and uncertainty analysis tools for composite indicators. In order to validate both approaches, a seven-phase research methodology was developed and applied to our case study. In addition, the priorization of environmental factors was calculated individually for each partner. The results allow managers to establish the competitive strategy that best suits th…