Now showing items 66-85 of 259

    • Centers of weight-homogeneous polynomial vector fields on the plane 

      Giné, Jaume; Llibre, Jaume; Valls, Claudia (American Mathematical Society, 2017)
      We characterize all centers of a planar weight-homogeneous polynomial vector fields. Moreover we classify all centers of a planar weight-homogeneous polynomial vector fields of degrees $6$ and $7$.
    • Characterizing identifying codes from the spectrum of a graph or digraph 

      Balbuena Martínez, Camino; Dalfó, Cristina; Martínez Barona, Berenice (Elsevier, 2019)
      A (1, ≤ ℓ)-identifying code in digraph D is a dominating subset C of vertices of D, such that all distinct subsets of vertices of D with cardinality at most ℓ have distinct closed in-neighborhoods within C. As far as we ...
    • Chiellini Hamiltonian Liénard differential systems 

      Giné, Jaume; Llibre, Jaume; Valls, Claudia (Texas State University, 2019)
      We characterize the centers of the Chiellini Hamiltonian Li´enard second-order differential equations x 0 = y, y 0 = −f(x)y − g(x) where g(x) = f(x)(k − α(1 + α) R f(x)dx) with α, k ∈ R. Moreover we study the ...
    • Clan information market games 

      El Obadi, Saadia; Miquel Fernández, Silvia (Springer US, 2016)
      We introduce a TU-game that describes a market where information is distributed among several agents and all these pieces of information are necessary to produce a good. This situation will be called clan information market. ...
    • Classical planar algebraic curves realizable by quadratic polynomial differential systems 

      García, I. A. (Isaac A.); Llibre, Jaume (World Scientific Publishing, 2017-11-15)
      In this paper we show planar quadratic polynomial differentialsystems exhibiting as solutions some famous planar invariant algebraic curves. Also we put particular attention to the Darboux integrability of these differential ...
    • Competition effects in cation binding to humic acid: conditional affinity spectra for fixed total metal concentration conditions 

      David, Calin; Mongin, Sandrine; Rey Castro, Carlos; Galceran i Nogués, Josep; Companys Ferran, Encarnació; Garcés, Josep Lluís; Salvador, José; Puy Llorens, Jaume; Cecilia Averós, Joan; Lodeiro, Pablo; Mas, Francesc (Elsevier, 2010)
      Information on the Pb and Cd binding to a purified Aldrich humic acid (HA) is obtained from the influence of different fixed total metal concentrations on the acid-base titrations of this ligand. NICA (Non-Ideal Competitive ...
    • Complete integrability, orbital linearizability and independent normalizers for local vector fields in R^n 

      García, I. A. (Isaac A.) (Heldermann Verlag, 2015)
      In this paper we study how are related three of the basic concepts in the rather non-generic phenomenon of integrability of analytic local vector fields X around an equilibrium in R, namely: complete integrability, orbital ...
    • Composition conditions in the trigonometric Abel equation 

      Giné, Jaume; Grau Montaña, Maite; Santallusia Esvert, Xavier (Shanghai Normal University & Wilmington Scientific Publisher, 2013)
      In this paper we deal with the center problem for the trigonometricAbel equation dρ/dρ =a1(θ)ρ^2+a2(θ)ρ^3; where a1(θ) and a2(θ)are trigonometric polynomials in θ. This problem is closely connectedwith the classical Poincar´e ...
    • Concepciones de los profesores sobre la enseñanza de las ecuaciones diferenciales a estudiantes de química y biología: estudio de casos 

      Moreno Moreno, Ma. del Mar; Azcárate, Carmen (Universitat Autònoma de Barcelona. Institut de Ciències de l'EducacióUniversitat de València, 1997)
      Intending to quest about the conceptions math teachers hold about how to teach Differential Equations to chemistry and biology students, we have devised a research tool which allows us to derive relevant information. We ...
    • Concepciones y creencias de los profesores universitarios de matemáticas acerca de la enseñanza de las ecuaciones diferenciales 

      Moreno Moreno, Ma. del Mar; Azcárate, Carmen (Universitat Autònoma de Barcelona. Institut de Ciències de l'EducacióUniversitat de València, 2003)
      La investigación que aquí presentamos es una aproximación a las concepciones y creencias de los profesores universitarios de matemáticas acerca de la enseñanza de las ecuaciones diferenciales en estudios científico-experimentales. ...
    • Connectivity and other invariants of generalized products of graphs 

      López Masip, Susana-Clara; Muntaner Batle, F. A. (Springer, 2015)
      Figueroa-Centeno et al. [4] introduced the following product of digraphs let D be a digraph and let Γ be a family of digraphs such that V (F) = V for every F∈Γ . Consider any function h:E(D)→Γ . Then the product D⊗hΓ is ...
    • Cyclicity of a class of polynomial nilpotent center singularities 

      García, I. A. (Isaac A.); Shafer, Douglas S. (American Institute of Mathematical Sciences, 2016-04-01)
      In this work we extend techniques based on computational algebra for bounding the cyclicity of nondegenerate centers to nilpotent centers in a natural class of polynomial systems, those of the form $\dot x = y + P_{2m + ...
    • Cyclicity of a simple focus via the vanishing multiplicity of inverse integrating factors 

      García, I. A. (Isaac A.); Llibre, Jaume; Maza Sabido, Susanna (Elsevier, 2013)
      First we provide new properties about the vanishing multiplicity of the inverse integrating factor of a planar analytic differential system at a focus. After we use this vanishing multiplicity for studying the cyclicity ...
    • Cyclicity of Nilpotent Centers with Minimum Andreev Number 

      García, I. A. (Isaac A.) (Springer, 2019-10-07)
      We consider polynomial families of real planar vector fields for which the origin is a monodromic nilpotent singularity having minimum Andree's number. There the centers are characterized by the existence of a formal inverse ...
    • Cyclicity of polynomial nondegenerate centers on center manifolds 

      García, I. A. (Isaac A.); Maza Sabido, Susanna; Shafer, Douglas S. (Elsevier, 2018-11-09)
      We consider polynomial families of ordinary differential equations on $\R^3$, parametrized by the admissible coefficients, for which the origin is an isolated singularity at which the linear part of the system has one ...
    • Cyclicity of some symmetric nilpotent centers 

      García, I. A. (Isaac A.) (Elsevier, 2016)
      In this work we present techniques for bounding the cyclicity of a wide class of monodromic nilpotent singularities of symmetric polynomial planar vector fields. The starting point is identifying a broad family of nilpotent ...
    • Cyclicity versus center problem 

      Gasull i Embid, Armengol; Giné, Jaume (Springer, 2010)
      We prove that there are one-parameter families of planar differential equations for which the center problem has a trivial solution and on the other hand the cyclicity of the weak focus is arbitrarily high. We illustrate ...
    • Degree diameter problem on honeycomb networks 

      Holub, Přemys; Miller, Mirka; Pérez Rosés, Hebert; Ryan, Joe (Elsevier, 2014-08-23)
      The degree diameter problem involves finding the largest graph (in terms of the number of vertices) subject to constraints on the degree and the diameter of the graph. Beyond the degree constraint there is no restriction ...
    • Degree/diameter problem for mixed graphs 

      López Lorenzo, Ignacio; Pérez Rosés, Hebert (Elsevier, 2015)
      The Degree/diameter problem asks for the largest graphs given diameter and maximum degree. This problem has been extensively studied both for directed and undirected graphs, ando also for special classes of graphs. In this ...
    • Determination of Zn2+ concentration with AGNES using different strategies to reduce the deposition time 

      Companys Ferran, Encarnació; Cecilia Averós, Joan; Codina Montull, Glòria; Puy Llorens, Jaume; Galceran i Nogués, Josep (Elsevier, 2005)
      Absence of gradient and Nernstian equilibrium stripping (AGNES) senses the free ion concentration of Zn(II) in solutions containing different ligands, being unaffected by the lack of reversibility of the Zn2+/Zn0 couple ...