Now showing items 1-20 of 358

    • 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 characterization of the generalized Liénard polynomial differential systems having invariant algebraic curves 

      Giné, Jaume; Llibre, Jaume (Elsevier, 2022)
      The generalized Liénard polynomial differential systems are the differential systems of the form x′ = y, y′ = − f(x)y − g(x), where f and g are polynomials. We characterize all the generalized Liénard polynomial ...
    • 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 computational model approach to assess the effect of climate change on the growth and development of tadpoles 

      Colomer, M. Àngels (Maria Àngels); Margalida, Antoni; Sanuy, Isabel; Llorente, Gustavo A.; Sanuy i Castells, Delfí; Pujol-Buixó, Eudal (Elsevier, 2021)
      All of the environmental conditions in nature act on an organism simultaneously. However, in experimental studies of the factors influencing metamorphosis, each factor needs to be examined individually in order to disentangle ...
    • 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 Digital Cash Paradigm with Valued and No-Valued e-Coins 

      Borges Llorens, Ricard; Sebé Feixas, Francesc (MDPI, 2021)
      Digital cash is a form of money that is stored digitally. Its main advantage when compared to traditional credit or debit cards is the possibility of carrying out anonymous transactions. Diverse digital cash paradigms have ...
    • 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, Francesc Antoni; 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 new sufficient condition in order that the real Jacobian conjecture in R2 holds 

      Giné, Jaume; Llibre, Jaume (Elsevier, 2021)
      Let F = (f, g) : R2 → R2 be a polynomial map such that det(DF (x, y)) is nowhere zero and F (0, 0) = (0, 0). In this work we give a new sufficient condition for the injectivity of F . We also state a conjecture when ...
    • 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 note on the order of iterated line digraphs 

      Dalfó, Cristina; Fiol, Miguel Angel (Wiley Periodicals Inc., 2016-06)
      Given a digraph G, we propose a new method to find therecurrence equation for the number of vertices nk of the k-iterated linedigraph Lk(G), for k≥0, where L0(G)=G. We obtain this result by usingthe minimal polynomial of ...
    • 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 ...