Envíos recientes

  • Convergent and asymptotic methods for second-order difference equations with a large parameter 

    Ferreira, Chelo; López García, José Luis; Pérez Sinusía, Ester (Springer, 2018)   Artículo / Artikulua
    We consider the second-order linear difference equation y(n+2)−2ay(n+1)−Λ2y(n)=g(n)y(n)+f(n)y(n+1) , where Λ is a large complex parameter, a≥0 and g and f are sequences of complex numbers. Two methods are proposed to find ...
  • Uniform convergent expansions of the Gauss hypergeometric function in terms of elementary functions 

    Ferreira, Chelo; López García, José Luis; Pérez Sinusía, Ester (Taylor & Francis, 2018)   Artículo / Artikulua
    We consider the hypergeometric function 2F1(a, b; c; z) for z ∈ C \ [1,∞). For Ra ≥ 0, we derive a convergent expansion of 2F1(a, b; c; z) in terms of the function (1 − z)−a and of rational functions of z that is uniformly ...
  • Uniform representation of the incomplete beta function in terms of elementary functions 

    Ferreira, Chelo; López García, José Luis; Pérez Sinusía, Ester (Kent State UniversityJohann Radon Institute (RICAM), 2018)   Artículo / Artikulua  OpenAccess
    We consider the incomplete beta function Bz(a, b) in the maximum domain of analyticity of its three variables: a, b, z ∈ C, −a /∈ N, z /∈ [1, ∞). For <b ≤ 1 we derive a convergent expansion of z−aBz(a, b) in terms of the ...
  • Convergent expansions of the confluent hypergeometric functions in terms of elementary functions 

    Bujanda Cirauqui, Blanca Upna; López García, José Luis; Pagola Martínez, Pedro Jesús (American Mathematical Society, 2018)   Artículo / Artikulua  OpenAccess
    We consider the confluent hypergeometric function M(a, b; z) for z ∈ C and Rb >Ra > 0, and the confluent hypergeometric function U(a, b; z) for b ∈ C, Ra > 0, and Rz > 0. We derive two convergent expansions of M(a, b; z); ...
  • The use of two-point Taylor expansions in singular one-dimensional boundary value problems I 

    Ferreira, Chelo; López García, José Luis; Pérez Sinusía, Ester (Elsevier, 2018)   Artículo / Artikulua
    We consider the second-order linear differential equation (x + 1)y′′ + f(x)y′ + g(x)y = h(x) in the interval (−1, 1) with initial conditions or boundary conditions (Dirichlet, Neumann or mixed Dirichlet-Neumann). The ...
  • Convergent expansions of the incomplete gamma functions in terms of elementary functions 

    Bujanda Cirauqui, Blanca Upna; López García, José Luis; Pagola Martínez, Pedro Jesús (World Scientific Publishing, 2017)   Artículo / Artikulua  OpenAccess
    We consider the incomplete gamma function γ(a,z) for Ra>0 and z∈C. We derive several convergent expansions of z−aγ(a,z) in terms of exponentials and rational functions of z that hold uniformly in z with Rz bounded from ...
  • A simplification of the stationary phase method: application to the Anger and Weber functions 

    López García, José Luis (Kent State UniversityJohann Radon Institute (RICAM), 2017)   Artículo / Artikulua  OpenAccess
    The main difficulty in the practical use of the stationary phase method in asymptotic expansions of integrals is originated by a change of variables. The coefficients of the asymptotic expansion are the coefficients of the ...
  • Convergent expansions of the Bessel functions in terms of elementary functions 

    López García, José Luis; Pagola Martínez, Pedro Jesús (Springer US, 2018)   Artículo / Artikulua  OpenAccess
    We consider the Bessel functions Jν (z) and Yν (z) for ν > −1/2 and z ≥ 0. We derive a convergent expansion of Jν (z) in terms of the derivatives of (sin z)/z, and a convergent expansion of Yν (z) in terms of derivatives ...
  • The Pearcey integral in the highly oscillatory region 

    López García, José Luis; Pagola Martínez, Pedro Jesús (Elsevier, 2016)   Artículo / Artikulua  OpenAccess
    We consider the Pearcey integral P(x, y) for large values of |y| and bounded values of |x|. The integrand of the Pearcey integral oscillates wildly in this region and the asymptotic saddle point analysis is complicated. ...
  • 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 ...
  • Effects of a soft-core coulomb potential on the dynamics of a hydrogen atom near a metal surface 

    Iñarrea, Manuel; Lanchares, Víctor; Palacián Subiela, Jesús Francisco Upna; Pascual, Ana Isabel; Salas, José Pablo; Yanguas Sayas, Patricia Upna (Elsevier, 2019)   Artículo / Artikulua
    The goal of this paper is to investigate the effects that the replacement of the Coulomb potential by a soft-core Coulomb potential produces in the classical dynamics of a perturbed Rydberg hydrogen atom. As example, we ...
  • Application of eco-design and life cycle assessment standards for environmental impact reduction of an industrial product 

    Navajas León, Alberto; Uriarte Elizaga, Leire; Gandía Pascual, Luis (MDPI, 2017)   Artículo / Artikulua  OpenAccess
    Eco-design is included within the framework of the standard for “Environmental management systems—Guidelines for incorporating Eco-design” (ISO 14006:2011). Eco-design process, as defined in standard, has six steps: (i) ...
  • Study of optical fiber sensors for cryogenic temperature measurements 

    Miguel Soto, Verónica de; Leandro González, Daniel Upna; López Aldaba, Aitor Upna; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
    In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg ...
  • Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation 

    Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna; Beato López, Juan Jesús; Rodríguez Velamazán, José Alberto; Sánchez Marcos, J.; Gómez Polo, Cristina; Cesari, Eduard (Springer Nature, 2017)   Artículo / Artikulua  OpenAccess
    Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic ...
  • Spatial gender-age-period-cohort analysis of pancreatic cancer mortality in Spain (1990-2013) 

    Etxeberria Andueza, Jaione Upna; Goicoa Mangado, Tomás Upna; López Abente, Gonzalo; Riebler, Andrea; Ugarte Martínez, María Dolores Upna (Public Library of Science, 2017)   Artículo / Artikulua  OpenAccess
    Recently, the interest in studying pancreatic cancer mortality has increased due to its high lethality. In this work a detailed analysis of pancreatic cancer mortality in Spanish provinces was performed using recent data. ...
  • Structurally oriented nano-sheets in Co thin films: changing their anisotropic physical properties by thermally-induced relaxation 

    Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna; Magén, César; Teresa, José María de; Ibarra, Manuel Ricardo; Madurga Pérez, Vicente Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
    We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment ...
  • Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption 

    Echeverría Morrás, Jesús Upna; Calleja, Ignacio; Moriones Jiménez, Paula Upna; Garrido Segovia, Julián José Upna (Beilstein-Institut, 2017)   Artículo / Artikulua  OpenAccess
    We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. ...
  • 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 ...
  • Dynamics of axially symmetric perturbed Hamiltonians in 1:1:1 resonance 

    Carrasco, Dante; Palacián Subiela, Jesús Francisco Upna; Vidal, Claudio; Vidarte, Jhon; Yanguas Sayas, Patricia Upna (Springer, 2018)   Artículo / Artikulua
    We study the dynamics of a family of perturbed three-degree-of-freedom Hamiltonian systems which are in 1:1:1 resonance. The perturbation consists of axially symmetric cubic and quartic arbitrary polynomials. Our analysis ...
  • Singular reduction of resonant Hamiltonians 

    Meyer, Kenneth Ray; Palacián Subiela, Jesús Francisco Upna; Yanguas Sayas, Patricia Upna (IOP PublishingLondon Mathematical Society, 2018)   Artículo / Artikulua
    We investigate the dynamics of resonant Hamiltonians with n degrees of freedom to which we attach a small perturbation. Our study is based on the geometric interpretation of singular reduction theory. The flow of the ...

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