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Search Results: 1 - 10 of 144612 matches for " Joaquin B Ordieres "
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Estudio de la Incertidumbre en la Programación de Actividades usando la Matriz de Estructura Dependiente
Gálvez,Edelmira D; Capuz-Rizo,Salvador F; Ordieres,Joaquin B;
Información tecnológica , 2012, DOI: 10.4067/S0718-07642012000100004
Abstract: a study about the effect of uncertainty on the planning of project activities using the dependency structure matrix (dsm) and grey theory. the grey theory is applied to represent the uncertainty in estimating project extension. as a result, the equations to determine the grey conventional time, the grey normal time and the grey normal time with natural overlap were developed. based on the case studies it is concluded that the application of the grey theory to the dsm allows: considering the uncertainty in project planning; ii) identifying the most critical stages; iii) analyzing the effect of the uncertainty of each stage in the total project duration; and iv) comparing different programming strategies.
Estudio de la Incertidumbre en la Programación de Actividades usando la Matriz de Estructura Dependiente Study of the Uncertainty of Task Programming using the Dependency Structure Matrix
Edelmira D Gálvez,Salvador F Capuz-Rizo,Joaquin B Ordieres
Información Tecnológica , 2012,
Abstract: Se presenta un estudio sobre el efecto de la incertidumbre en la programación de actividades de proyectos usando la matriz de estructura dependiente (DSM) y la teoría gris. Se aplica la teoría gris para representar la incertidumbre en la estimación del tiempo de duración de proyectos, desarrollando las ecuaciones necesarias para determinar el tiempo convencional gris, el tiempo normal gris y el tiempo normal gris con superposición natural. Con base en el estudio se concluye que la aplicación de la teoría de gris a la DSM permite: i) considerar la incertidumbre en la programación del proyecto; ii) identificar las etapas más críticas; iii) analizar el efecto de la incertidumbre de cada etapa en la duración total del proyecto; y iv) comparar diferentes estrategias de programación. A study about the effect of uncertainty on the planning of project activities using the dependency structure matrix (DSM) and grey theory. The grey theory is applied to represent the uncertainty in estimating project extension. As a result, the equations to determine the grey conventional time, the grey normal time and the grey normal time with natural overlap were developed. Based on the case studies it is concluded that the application of the grey theory to the DSM allows: considering the uncertainty in project planning; ii) identifying the most critical stages; iii) analyzing the effect of the uncertainty of each stage in the total project duration; and iv) comparing different programming strategies.
Fast, Accurate and Robust Adaptive Finite Difference Methods for Fractional Diffusion Equations: The Size of the Timesteps does Matter
Santos B. Yuste,Joaquin Quintana-Murillo
Mathematics , 2014,
Abstract: The computation time required by standard finite difference methods with fixed timesteps for solving fractional diffusion equations is usually very large because the number of operations required to find the solution scales as the square of the number of timesteps. Besides, the solutions of these problems usually involve markedly different time scales, which leads to quite inhomogeneous numerical errors. A natural way to address these difficulties is by resorting to adaptive numerical methods where the size of the timesteps is chosen according to the behaviour of the solution. A key feature of these methods is then the efficiency of the adaptive algorithm employed to dynamically set the size of every timestep. Here we discuss two adaptive methods based on the step-doubling technique. These methods are, in many cases, immensely faster than the corresponding standard method with fixed timesteps and they allow a tolerance level to be set for the numerical errors that turns out to be a good indicator of the actual errors.
Desarrollo de un cerrojo artificial para el skin-pass en una línea de acero galvanizado por inmersión en caliente
González-Marcos, A.,Ordieres-Meré, J. B.,Pernía-Espinoza, A. V.,Torre-Suárez, V.
Revista de Metalurgia , 2008,
Abstract: In this paper, we present the application of data mining techniques to develop an “artificial lock” for the skin-pass in an attempt to solve a problem that can arise during the galvanising manufacturing process: the wrong labelling of the steel grade of a coil. In order to detect these errors and thus to avoid that coils with different properties than expected end up with a client, we propose neural network-based models for on-line predicting the strip elongation in the skin-pass section according to the manufacturing conditions and its chemical composition. Thus, a significant difference between estimated and measured elongation would mean that the coil must be removed from the line for further analyses. En este trabajo se presenta la aplicación de técnicas de minería de datos en el desarrollo de un “cerrojo artificial” para el skin-pass, que permita solucionar un problema que puede presentarse en la fabricación de bobinas de acero galvanizado: el etiquetado incorrecto del grado de acero de una bobina. Para tratar de detectar estos errores y evitar así que los clientes reciban bobinas con propiedades distintas de las esperadas, se proponen modelos, basados en redes neuronales, que predicen on-line el alargamiento de las bobinas en el skin-pass en función de las variables del proceso de fabricación y de su composición química. De esta forma, si la diferencia entre el alargamiento que estima el modelo y el medido realmente es significativa, se hace necesario sacar la bobina de la línea para someterla a análisis más exhaustivos.
Comparison on Sufficient Conditions for the Stability of Hill Equation: An Arnold’s Tongues Approach  [PDF]
Carlos A. Franco, Joaquin Collado
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.810109
Abstract:
It is known that the solutions of a second order linear differential equation with periodic coefficients are almost always analytically impossible to obtain and in order to study its properties we often require a computational approach. In this paper we compare graphically, using the Arnold Tongues, some sufficient criteria for the stability of periodic differential equations. We also present a brief explanation on how the authors, of each criterion, obtained them. And a comparison between four sufficient stability criteria and the stability zones found by perturbation methods is presented.
Finite Dimensional Approximation of the Monodromy Operator of a Periodic Delay Differential Equation with Piecewise Constant Orthonormal Functions  [PDF]
Eli A. Vazquez, Joaquin Collado
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.911086
Abstract:
Using piecewise constant orthonormal functions, an approximation of the monodromy operator of a Linear Periodic Delay Differential Equation (PDDE) is obtained by approximating the integral equation corresponding to the PDDE as a linear operator over the space of initial conditions. This approximation allows us to consider the state space as finite dimensional resulting in a finite matrix approximation whose spectrum converges to the spectrum of the monodromy operator.
En torno a la ‘Historia de la locura’; la polémica Foucault - Derrida
Joaquin Fortanet
Revista Observaciones Filosóficas , 2008,
Abstract: This text tries to analyze the controversy between Foucault and Derrida about the publication of Madness and Civilization in 1961. In this controversy we find crucial questions in order to understand concepts such as event, text or the division between reason and madness. Taking a distant perspective of their readings, both Foucault and Derrida propose different routes which start from the same new theoretical impulse called post-structuralism but, in the end, both authors obtain a radically different endings as for ontological matters.
Corpus COFLA: A research corpus for the Computational study of Flamenco Music
Nadine Kroher,José-Miguel Díaz-Bá?ez,Joaquin Mora,Emilia Gómez
Computer Science , 2015,
Abstract: Flamenco is a music tradition from Southern Spain which attracts a growing community of enthusiasts around the world. Its unique melodic and rhythmic elements, the typically spontaneous and improvised interpretation and its diversity regarding styles make this still largely undocumented art form a particularly interesting material for musicological studies. In prior works it has already been demonstrated that research on computational analysis of flamenco music, despite it being a relatively new field, can provide powerful tools for the discovery and diffusion of this genre. In this paper we present corpusCOFLA, a data framework for the development of such computational tools. The proposed collection of audio recordings and meta-data serves as a pool for creating annotated subsets which can be used in development and evaluation of algorithms for specific music information retrieval tasks. First, we describe the design criteria for the corpus creation and then provide various examples of subsets drawn from the corpus. We showcase possible research applications in the context of computational study of flamenco music and give perspectives regarding further development of the corpus.
Vibrational Stabilization by Reshaping Arnold Tongues: A Numerical Approach  [PDF]
Joaquin Collado, Hildeberto Jardón-Kojakhmetov
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.716163
Abstract: This paper presents two contributions to the stability analysis of periodic systems modeled by a Hill equation: The first is a new method for the computation of the Arnold Tongues associated to a given Hill equation which is based on the discretization of the latter. Using the proposed method, a vibrational stabilization is performed by a change in the periodic function which guarantees stability, given that the original equation has unbounded solutions. The results are illustrated by some examples.
Nonlinear preferential rewiring in fixed-size networks as a diffusion process
Samuel Johnson,Joaquin J. Torres,Joaquin Marro
Physics , 2009, DOI: 10.1103/PhysRevE.79.050104
Abstract: We present an evolving network model in which the total numbers of nodes and edges are conserved, but in which edges are continuously rewired according to nonlinear preferential detachment and reattachment. Assuming power-law kernels with exponents alpha and beta, the stationary states the degree distributions evolve towards exhibit a second order phase transition - from relatively homogeneous to highly heterogeneous (with the emergence of starlike structures) at alpha = beta. Temporal evolution of the distribution in this critical regime is shown to follow a nonlinear diffusion equation, arriving at either pure or mixed power-laws, of exponents -alpha and 1-alpha.
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