Now showing items 21-40 of 329

    • A second order analysis of the periodic solutions for nonlinear periodic differential systems with a small parameter 

      Buica, Adriana; Giné, Jaume; Llibre, Jaume (Elsevier, 2012)
      We deal with nonlinear T–periodic differential systems depending on a small parameter. The unperturbed system has an invariant manifold of periodic solutions. We provide the expressions of the bifurcation functions up to ...
    • A sufficient condition in order that the real Jacobian conjecture in R^2 holds 

      Braun, Francisco; Giné, Jaume; Llibre, Jaume (Elsevier, 2016)
      Let F=(f,g):R2→R2 be a polynomial map such that det⁡DF(x,y) is different from zero for all (x,y)∈R2 and F(0,0)=(0,0). We prove that for the injectivity of F it is sufficient to assume that the higher homogeneous terms of ...
    • A survey of isochronous centers 

      Chavarriga Soriano, Javier; Sabatini, Marco (Edicions de la Universitat de Lleida, 1999)
    • A survey on the inverse integrating factor 

      García, I. A. (Isaac A.); Grau Montaña, Maite (Springer, 2010)
      The relation between limit cycles of planar differential systems and the inverse integrating factor was first shown in an article of Giacomini, Llibre and Viano appeared in 1996. From that moment on, many research articles ...
    • A survey on the missing Moore graph 

      Dalfó, Cristina (Elsevier, 2019-01-16)
      This is a survey on some known properties of the possible Moore graph (or graphs) ϒ with degree 57 and diameter 2. Moreover, we give some new results about it, such as the following. When we consider the distance partition ...
    • A two-stage stochastic programming model for scheduling replacements in sow farms 

      Rodríguez Sánchez, Sara Verónica; Albornoz Sanhueza, Victor Manuel; Pla Aragonés, Lluís Miquel (Springer Verlag, 2009)
      This paper presents a formulation and resolution of a two-stage stochastic linear programming model with recourse for sow farms producing piglets. The proposed model considers a medium-term planning horizon and specifically ...
    • A variant of the McKay-Miller-Siran construction for Mixed Graphs 

      López Lorenzo, Ignacio; Pérez Rosés, Hebert; Pujolàs Boix, Jordi; Zdimalovà, Maria (Elsevier B.V., 2016-09-27)
      The Degree/Diameter Problem is an extremal problem in graph theory with applications in network design. One of the main research areas in the Degree/Diameter Problem consists of finding large graphs whose order approach ...
    • Accumulation of Mg to Diffusive Gradients in Thin Films (DGT) devices: Kinetic and thermodynamic effects of the ionic strength 

      Altier Infantes, Alexandra; Jiménez-Piedrahita, Martín; Rey Castro, Carlos; Cecilia Averós, Joan; Galceran i Nogués, Josep; Puy Llorens, Jaume (American Chemical Society, 2016-09-23)
      Availability of magnesium is a matter of concern due to its role in many environmental and biological processes. Diffusive Gradients in Thin Films (DGT) devices can measure Mg availability in situ. This work shows that Mg ...
    • Actitudes hacia la estadística y su evaluación 

      Estrada Roca, M. Asunción (2003)
      En este trabajo analizamos la problemática de la evaluación de las actitudes de los profesores hacía la Estadística. Es ésta una materia de reciente incorporación al curriculum de Educación Primaría y los profesores que ...
    • AGNES: a new electroanalytical technique for measuring free metal ion concentration 

      Galceran i Nogués, Josep; Companys Ferran, Encarnació; Puy Llorens, Jaume; Cecilia Averós, Joan; Garcés, Josep Lluís (Elsevier, 2004)
      AGNES (absence of gradients and Nernstian equilibrium stripping) is a stripping technique consisting of two conceptual steps: (i) application of a potential program (e.g. a step at a fixed potential) generating a known ...
    • Algebraic and computer-based methods in the undirected degree=diameter problem – a brief survey 

      Pérez Rosés, Hebert (Indonesian Combinatorial Society (InaCombS); Graph Theory and Applications (GTA) Research Centre; University of Newcastle (Australia); Institut Teknologi Bandung (ITB) (Indonesia), 2014)
      This paper discusses the most popular algebraic techniques and computational methods that have been used to construct large undirected graphs with given degree and diameter.
    • Algorithms and cryptographic protocols using elliptic curves 

      Miret, Josep M. (Josep Maria); Moreno Chiral, Ramiro; Pujolàs Boix, Jordi; Valls Marsal, Magda (Institut d'Estudis Catalans. Secció de Ciències i Tecnologia, 2007)
      En els darrers anys, la criptografia amb corbes el.líptiques ha adquirit una importància creixent, fins a arribar a formar part en la actualitat de diferents estàndards industrials. Tot i que s'han dissenyat variants amb ...
    • Algunas propiedades de un algoritmo de clasificación piramidal 

      Capdevila Marqués, Carles; Gil Estallo, Àngel J.; Arcas Pons, Antoni (Instituto Nacional de Estadística, 1995)
      En este trabajo se enuncia un Algoritmo de Clasificacián Ascendente Piramidal y se establecen algunas de sus propiedades, que ponen de manifiesto la mejora que éste supone respecto a otros algoritmos establecidos con ...
    • Aligning Business Processes With the Services Layer Using a Semantic Approach 

      Sosa-Sánchez, Encarna; Clemente, Pedro J.; Prieto, Álvaro E.; Ortiz-Caraballo, Carmen (Institute of Electrical and Electronics Engineers (IEEE), 2019)
      Organizations require their business processes goals and the underlying information technology (IT) to be in synchronization with each other, but the continual changes in business processes makes this difficult. To accomplish ...
    • An algebraic approach to lifts of digraphs 

      Dalfó, Cristina; Fiol, Miguel Angel; Miller, Mirka; Ryan, Joe; Sirán, Jozef (Elsevier, 2018)
      We present some applications of a new matrix approach for studying the properties of the lift of a voltage digraph, which has arcs weighted by the elements of a group. As a main result, when the involved group is Abelian, ...
    • An improved Moore bound and some new optimal families of mixed Abelian Cayley graphs 

      Dalfó, Cristina; Fiol, Miguel Angel; López Lorenzo, Ignacio; Ryan, Joe (Elsevier, 2020)
      We consider the case in which mixed graphs (with both directed and undirected edges) are Cayley graphs of Abelian groups. In this case, some Moore bounds were derived for the maximum number of vertices that such graphs can ...
    • An improved upper bound for the order of mixed graphs 

      Dalfó, Cristina; Fiol, Miguel Angel; López Lorenzo, Ignacio (Elsevier B.V., 2018)
      A mixed graph G can contain both (undirected) edges and arcs (directed edges). Here we derive an improved Moore-like bound for the maximum number of vertices of a mixed graph with diameter at least three. Moreover, a ...
    • Analysing spatial correlation of weeds and harvester ants in cereal fields using point processes 

      Comas Rodríguez, Carles; Royo-Esnal, Aritz; Recasens i Guinjuan, Jordi; Torra Farré, Joel (Springer Verlag, 2016)
      The interaction between the spatial distribution of weed richness and weed cover and the spatial location of harvester ant nets was investigated in cereal fields. The understanding of such interdependencies can be relevant ...
    • Analytic integrability around a nilpotent singularity 

      Algaba, Antonio; García, Cristóbal; Giné, Jaume (Elsevier, 2019)
      In this work it is characterized the analytic integrability problem around a nilpotent singularity of a differential system in the plane under generic conditions.
    • Analytic integrability around a nilpotent singularity: The non-generic case 

      Algaba, Antonio; Díaz, María; García, Cristóbal; Giné, Jaume (American Institute of Mathematical Sciences, 2020)
      Recently, in [9] is characterized the analytic integrability problem around a nilpotent singularity for differential systems in the plane under generic conditions. In this work we solve the remaining case completing the ...