Now showing items 66-85 of 259

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

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(American Institute of Mathematical Sciences, 2016-04-01)
• #### Cyclicity of some symmetric nilpotent centers ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ﻿

(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 ...