Now showing items 34-53 of 53

    • New fractional step Runge-Kutta-Nyström methods up to order three 

      Bujanda Cirauqui, Blanca Upna; Moreta, M. Jesús; Jorge Ulecia, Juan Carlos Upna (Elsevier, 2020)   Artículo / Artikulua
      Fractional Step Runge–Kutta–Nyströ (FSRKN) methods have been revealed to be an excellent option to integrate numerically many multidimensional evolution models governed by second order in time partial differential equations. ...
    • Normalization through invariants in n-dimensional Kepler problems 

      Meyer, Kenneth Ray; Palacián Subiela, Jesús Francisco Upna; Yanguas Sayas, Patricia Upna (Pleiades Publishing, 2018)   Artículo / Artikulua  OpenAccess
      We present a procedure for the normalization of perturbed Keplerian problems in n dimensions based on Moser regularization of the Kepler problem and the invariants associated to the reduction process. The approach allows ...
    • The null space of fuzzy inclusion measures 

      Couso, Inés; Bustince Sola, Humberto Upna; Fernández Fernández, Francisco Javier Upna; Sánchez, Luciano (IEEE, 2019)   Artículo / Artikulua
      Some formal relationships between the different axiomatic definitions of inclusion measure are analysed. In particular, the links between the different proposals about the null-space (the collection of pairs associated ...
    • On a particular class of Meijer's G functions appearing in fractional calculus 

      Karp, D. B.; López García, José Luis Upna (Academic Publications, 2018)   Artículo / Artikulua  OpenAccess
      In this paper we investigate the Meijer G-function G p+1,p+1 p,1 which, for certain parameter values, represents the Riemann-Liouville fractional integral of the Meijer-Nørlund function G p,p. p,0 The properties of this ...
    • On co-orbital quasi-periodic motion in the three-body problem 

      Cors, Josep Maria; Palacián Subiela, Jesús Francisco Upna; Yanguas Sayas, Patricia Upna (Society for Industrial and Applied Mathematics (SIAM), 2019)   Artículo / Artikulua  OpenAccess
      Within the framework of the planar three-body problem we establish the existence of quasi-periodic motions and KAM 4-tori related to the co-orbital motion of two small moons about a large planet where the moons move in ...
    • On fixed point theory in partially ordered sets and an application to asymptotic complexity of algorithms 

      Estevan Muguerza, Asier Upna; Miñana, Juan José; Valero, Óscar (Springer, 2019)   Artículo / Artikulua
      The celebrated Kleene fixed point theorem is crucial in the mathematical modelling of recursive specifications in Denotational Semantics. In this paper we discuss whether the hypothesis of the aforementioned result can be ...
    • Online relative risks/rates estimation in spatial and spatio-temporal disease mapping 

      Adin Urtasun, Aritz Upna; Goicoa Mangado, Tomás Upna; Ugarte Martínez, María Dolores Upna (Elsevier, 2019)   Artículo / Artikulua
      Background and objective: Spatial and spatio-temporal analyses of count data are crucial in epidemiology and other fields to unveil spatial and spatio-temporal patterns of incidence and/or mortality risks. However, fitting ...
    • Orness measurements for lattice m-dimensional interval-valued OWA operators 

      Miguel Turullols, Laura de Upna; Paternain Dallo, Daniel Upna; Lizasoain Iriso, María Inmaculada Upna; Ochoa Lezaun, Gustavo Upna; Bustince Sola, Humberto Upna (Elsevier, 2018)   Artículo / Artikulua
      Ordered weighted average (OWA) operators are commonly used to aggregate information in multiple situations, such as decision making problems or image processing tasks. The great variety of weights that can be chosen to ...
    • Periodic solutions, KAM tori and bifurcations in a cosmology-inspired potential 

      Palacián Subiela, Jesús Francisco Upna; Vidal Díaz, Claudio; Vidarte, Jhon; Yanguas Sayas, Patricia Upna (IOP Publishing, 2019)   Artículo / Artikulua
      A family of perturbed Hamiltonians H = 1/2 (x^2 + X^2) − 1/2 (y^2 + Y^2)+1/2 (z^2 + Z^2) + 2[ (x^4 + y^4 + z^4) + (x^2 y^2 + x^2 z^2 + y^2 z^2)] in 1: −1:1 resonance depending on two real parameters is considered. We ...
    • The problem of the last bed: contextualization and a new simulation framework for analyzing physician decisions 

      Azcárate Camio, Cristina Upna; Esparza, Laida; Mallor Giménez, Fermín Upna (Elsevier, 2019)   Artículo / Artikulua  OpenAccess
      Faced with a full Intensive Care Unit (ICU), physicians need to decide between turning away a new patient in need of critical care and creating a vacancy by prematurely discharging a current occupant. This dilemma is widely ...
    • Reduction of the size of L-fuzzy contexts. A tool for differential diagnoses of diseases 

      Alcalde, Cristina; Burusco Juandeaburre, Ana Upna (Taylor & Francis, 2019)   Artículo / Artikulua
      Information extraction from an L-fuzzy context becomes a hard problem when we work with a large set of objects and/or attributes. The goal of this paper is to present two different and complementary techniques to reduce ...
    • Scale recoding in sociological research: a new validation methodology. An application to a political survey 

      Abascal Fernández, Elena Upna; Díaz de Rada Igúzquiza, Vidal Upna; García Lautre, Ignacio Upna; Landaluce, M. Isabel (CSIC, 2019)   Artículo / Artikulua  OpenAccess
      La recodificación de variables es una etapa habitual en el análisis de datos de encuesta. No está exenta de riesgos, como pueden ser la introducción de sesgos o las posibles deformaciones de los datos originales. En este ...
    • Short- and mid-term evaluation of the use of electric vehicles in urban freight transport collaborative networks: a case study 

      Muñoz Villamizar, Andrés; Quintero Araújo, Carlos L.; Montoya Torres, Jairo R.; Faulín Fajardo, Javier Upna (Taylor & Francis, 2019)   Artículo / Artikulua  OpenAccess
      Despite its negative impacts, freight transportation is a primary component of all supply chains. Decision makers have considered diverse strategies, such as Horizontal Collaboration (HC) and the usage of alternative types ...
    • Strengthened ordered directionally monotone functions. Links between the different notions of monotonicity 

      Sesma Sara, Mikel Upna; Lafuente López, Julio Upna; Roldán, Antonio; Mesiar, Radko; Bustince Sola, Humberto Upna (Elsevier, 2019)   Artículo / Artikulua
      In this work, we propose a new notion of monotonicity: strengthened ordered directional monotonicity. This generalization of monotonicity is based on directional monotonicity and ordered directional monotonicity, two recent ...
    • Strong stability preserving properties of composition Runge-Kutta schemes 

      Higueras Sanz, Inmaculada Upna; Roldán Marrodán, Teodoro Upna (Springer, 2019)   Artículo / Artikulua
      In this paper Strong Stability Preserving (SSP) properties of Runge Kutta methods obtained by com- posing k different schemes with different step sizes are studied. The SSP coefficient of the composition method is obtained ...
    • Tailoring the structural and magnetic properties of Co-Zn nanosized ferrites for hyperthermia applications 

      Gómez Polo, Cristina Upna; Recarte Callado, Vicente Upna; Cervera Gabalda, Laura María Upna; Beato López, Juan Jesús Upna; López García, Javier Upna; Rodríguez Velamazán, José Alberto; Ugarte Martínez, María Dolores Upna; Mendonça, E. C.; Duque, J. G. S. (Elsevier, 2018)   Artículo / Artikulua
      A comparative study of the magnetic properties (magnetic moment, magnetocrystalline anisotropy) and hyperthermia response in Co-Zn spinel nanoparticles is presented. The CoxZn1-xFe2O4 nanoparticles (x = 1, 0.5, 0.4, 0.3, ...
    • Temperature and water availability during maturation affect the cytokinins and auxins profile of radiata pine somatic embryos 

      Moncaleán, Paloma; García Mendiguren, Olatz; Novák, Ondrej; Strnad,Miroslav; Goicoa Mangado, Tomás Upna; Ugarte Martínez, María Dolores Upna; Montalbán, Itziar A. (Frontiers Media, 2018)   Artículo / Artikulua  OpenAccess
      Somatic embryogenesis (SE) provides us a potent biotechnological tool to manipulate the physical and chemical conditions (water availability) along the process and to study their effect in the final success in terms of ...
    • Three categories of set-valued generalisations from fuzzy sets to interval-valued and Atanassov intuitionistic fuzzy sets 

      Couso, Inés; Bustince Sola, Humberto Upna (IEEE, 2018)   Artículo / Artikulua  OpenAccess
      Many different notions included in the fuzzy set literature can be expressed in terms of functionals defined over collections of tuples of fuzzy sets. During the last decades, different authors have independently generalised ...
    • Unconditional and quasi-greedy bases in L-p with applications to Jacobi polynomials Fourier series 

      Albiac Alesanco, Fernando José Upna; Ansorena, José L.; Ciaurri, Óscar; Varona, Juan L. (European Mathematical Society, 2019)   Artículo / Artikulua  OpenAccess
      We show that the decreasing rearrangement of the Fourier series with respect to the Jacobi polynomials for functions in L-p does not converge unless p = 2. As a by-product of our work on quasi-greedy bases in L-p(µ), we ...
    • A unified view of different axiomatic measures defined on L-fuzzy sets 

      Couso, Inés; Bustince Sola, Humberto Upna; Sánchez, Luciano (IEEE, 2019)   Artículo / Artikulua
      The recent literature contains a multitude of extensions of (axiomatic) notions from the context of ordinary fuzzy sets to more general contexts. Using the language of lattices, we provide a general and compact formulation ...