Now showing items 1-20 of 293

    • A blow-up method to prove formal integrability for some planar differential systems 

      Fercec, Brigita; Giné, Jaume (Shanghai Normal University & Wilmington Scientific Publisher, 2018)
      In this work we provide an effective method to prove the formal integrability of the resonant saddles. The method is based on the use of a blow-up and the resolution of a recurrence differential equation using induction. ...
    • A Chebyshev criterion for Abelian integrals 

      Grau Montaña, Maite; Mañosas, Francesc; Villadelprat, Jordi (American Mathematical Society, 2010)
      We present a criterion that provides an easy sufficient condition in order that a collection of Abelian integrals has the Chebyshev property. This condition involves the functions in the integrand of the Abelian integrals ...
    • A Construction for Providing Reusability to Mobile Phone-Based e-Tickets 

      Borges Llorens, Ricard; Sebé Feixas, Francesc (IEEE, 2020)
      Nowadays, the use of electronic tickets in public transport is a reality. Several mobile phone-based e-ticket systems have been proposed so far. Even so, very few of them include reusability in the sense that a single ...
    • A counterexample to the composition condition conjecture for polynomial Abel differential equations 

      Giné, Jaume; Grau Montaña, Maite; Santallusia Esvert, Xavier (Cambridge University Press, 2019)
      Polynomial Abel differential equations are considered a model problem for the classical Poincaré center–focus problem for planar polynomial systems of ordinary differential equations. In the last few decades, several works ...
    • A general method to obtain the spectrum and local spectra of a graph from its regular partitions 

      Dalfó, Cristina; Fiol, Miguel Angel (International Linear Algebra Society, 2020-07-12)
      It is well known that, in general, part of the spectrum of a graph can be obtained from the adjacency matrix of its quotient graph given by a regular partition. In this paper, a method that gives all the spectrum, and also ...
    • A Green Strategy for Federated and Heterogeneous Clouds with Communicating Workloads 

      Mateo Fornés, Jordi; Vilaplana Mayoral, Jordi; Solsona Tehàs, Francesc; Pla Aragonés, Lluís Miquel; Lérida Monsó, Josep Lluís (Hindawi Publishing Corporation, 2014-07)
      Providers of cloud environments must tackle the challenge of configuring their system to provide maximal performance while minimizing the cost of resources used. However, at the same time, they must guarantee an SLA ...
    • A method for characterizing nilpotent centers 

      Giné, Jaume; Llibre, Jaume (Elsevier, 2014)
      To characterize when a nilpotent singular point of an analytic differential system is a center is of particular interest, first for the problem of distinguishing between a focus and a center, and after for studying the ...
    • A Moore-like bound for mixed abelian Cayley graphs 

      López Lorenzo, Ignacio; Pérez Rosés, Hebert; Pujolàs Boix, Jordi (Elsevier B.V., 2016-09-26)
      We give an upper bound for the number of vertices in mixed abelian Cayley graphs with given degree and diameter.
    • A new approach to gross error detection for GPS networks 

      Dalfó, Cristina; Fiol, Miguel Angel (Elsevier, 2019)
      We present a new matrix-based approach to detect and correct gross errors in GPS geodetic control networks. The study is carried out by introducing a new matrix, whose entries are powers of a (real or complex) variable, ...
    • A new general family of mixed graphs 

      Dalfó, Cristina (Elsevier, 2018)
      A new general family of mixed graphs is presented, which generalizes both the pancake graphs and the cycle prefix digraphs. The obtained graphs are vertex transitive and, for some values of the parameters, they constitute ...
    • A new labeling construction from the ⊗h-product 

      López Masip, Susana-Clara; Muntaner Batle, F. A.; Prabu, M. (Elsevier, 2017)
      The -product that is referred in the title was introduced in 2008 as a generalization of the Kronecker product of digraphs. Many relations among labelings have been obtained since then, always using as a second factor a ...
    • A New Normal Form for Monodromic Nilpotent Singularities of Planar Vector Fields 

      Algaba, Antonio; García, Cristóbal; Giné, Jaume (Springer, 2021)
      In this work, we present a new technique for solving the center problem for nilpotent singularities which consists of determining a new normal form conveniently adapted to study the center problem for this singularity. In ...
    • A note on a new general family of deterministic hierarchical networks 

      Dalfó, Cristina; Fiol, Miguel Angel (World Scientific Publishing, 2019)
      It is known that many networks modeling real-life complex systems are small-word (large local clustering and small diameter) and scale-free (power law of the degree distribution), and very often they are also hierarchical. ...
    • A note on Liouvillian first integrals and invariant algebraic curves 

      Giné, Jaume; Grau Montaña, Maite; Llibre, Jaume (Elsevier, 2013-02)
      In this work we study the existence and non-existence of finite invariant algebraic curves for a complex planar polynomial differential system having a Liouvillian first integral.
    • A Privacy-Preserving Pay-by-Phone Parking System 

      Garra Oronich, Ricard; Martínez Rodríguez, Santi; Sebé Feixas, Francesc (Institute of Electrical and Electronics Engineers (IEEE), 2017)
      Most cities around the world require drivers to pay for the time they occupy a parking spot. In this way, drivers are encouraged to shorten parking time so that other drivers are given a reasonable chance of finding ...
    • A privacy-preserving reputation system with user rewards 

      Busom Figueres, Núria; Petrlic, R.; Sebé Feixas, Francesc; Sorge, C.; Valls Marsal, Magda (Elsevier, 2017)
      Reputation systems are useful to assess the trustworthiness of potential transaction partners, but also a potential threat to privacy since rating profiles reveal users’ preferences. Anonymous reputation systems resolve this ...
    • A problem on edge-magic labelings of cycles 

      López Masip, Susana-Clara; Muntaner Batle, F. A.; Rius Font, Miquel (Cambridge University Press, 2014-06-14)
      Kotzig and Rosa defined in 1970 the concept of edge-magic labelings as follows: let G be a simple (p, q)-graph (that is, a graph of order p and size q without loops or multiple edges). A bijective function f : V (G)∪E(G) ...
    • 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)