Browsing Articles publicats (Matemàtica) by Title
Now showing items 183202 of 259

On the Formal Integrability Problem for Planar Differential Systems
(Hindawi Publishing Corporation, 2013)We study the analytic integrability problem through the formal integrability problem and we show its connection, in some cases, with the existence of invariant analytic (sometimes algebraic) curves. From the results ... 
On the Integrability of Liénard systems with a strong saddle
(Elsevier, 2017)We study the local analytic integrability for real Li\'{e}nard systems, $\dot x=yF(x),$ $\dot y= x$, with $F(0)=0$ but $F'(0)\ne0,$ which implies that it has a strong saddle at the origin. First we prove that this problem ... 
On the multiple zeros of a real analytic function with applications to the averaging theory of differential equations
(IOP Publishing, 20181121)In this work we consider real analytic functions $d(z,\la,\e)$, where $d : \Omega \times \mathbb{R}^p \times I \to \Omega$, $\Omega$ is a bounded open subset of $\R$, $I \subset \mathbb{R}$ is an interval containing the ... 
On the origin of the deflection of light
(Elsevier, 2008)Action at distance in Newtonian physics is replaced by finite propagation speeds in classical post–Newtonian physics. As a result, the differential equations of motion in Newtonian physics are replaced by functional ... 
On the origin of the inertia: the modified Newtonian dynamics theory
(Elsevier, 2009)The sameness between the inertial mass and the gravitational mass is an assumption and not a consequence of the equivalent principle is shown. In the context of the Sciama’s inertia theory, the sameness between the inertial ... 
On the periodic orbit bifurcating from a Hopf bifurcation in systems with two slow and one fast variables
(Elsevier, 2014)The Hopf bifurcation in slowfast systems with two slow variables and one fast variable has been studied recently, mainly from a numerical point of view. Our goal is to provide an analytic proof of the existence of the ... 
On the planar integrable differential systems
(Springer Verlag, 2011)Under very general assumptions we prove that the planar differential systems having a first integral are essentially the linear differential systems u˙ = u, ˙v = v. Additionally such systems always have a Lie symmetry. We ... 
On the Randić index of graphs
(Elsevier, 20180911)For a given graph G = (V, E), the degree mean rate of an edge uv ∈ E is a half of the quotient between the geometric and arithmetic means of its endvertex degrees d(u) and d(v). In this note, we derive tight bounds for ... 
On Vosperian and Superconnected VertexTransitive Digraphs
(Springer, 2013)We investigate the structure of a digraph having a transitive automorphism group where every cutset of minimal cardinality consists of all successors or all predecessors of some vertex. We give a complete characterization ... 
Open problems involving super edgemagic labelings and related topics
(Institute of Combinatorics and its Applications, 2012)Graph labelings has experimented a fast development during the last four decades. Two books dedicated to this topic, a very complete survey on the subject and over 1000 papers in the literature constitute a good proof of ... 
Optimizing the enzymatic elimination of clogging of a microfiltration membrane by Parellada grape cake
(Wiley, 2016)Clogging of the filtration membranes is one of the main problems in the process of obtaining grape must for white wine; therefore, clogging must be reduced to the maximum. The aim of this work was to find the optimal values ... 
Perfect (super) EdgeMagic Crowns
(Springer, 2017)A graph G is called edgemagic if there is a bijective function f from the set of vertices and edges to the set {1,2, ,V(G)+E(G)} such that the sum f(x)+f(xy)+f(y) for any xy in E(G) is constant. Such a function is ... 
Period annulus of the harmonic oscillator with zero cyclicity under perturbations with a homogeneous polynomial field
(Bolyai Institute. University of SzegedHungarian Academy of Sciences, 20190114)In this work we prove, using averaging theory at any order in the small perturbation parameter, that the period annulus of the harmonic oscillator has cyclicity zero (no limit cycles bifurcate) when it is perturbed by any ... 
Periodic orbits in Hyperchaotic Chen systems
(Texas State University, 2015)In this work, we show a zeroHopf bifurcation in a Hyperchaotic Chen system. Using averaging theory, we prove the existence of two periodic orbits bifurcating from the zeroHopf equilibria located at the origin of ... 
Periodic solutions for nonlinear differential systems: the second order bifurcation function
(Nicolaus Copernicus University in Torun, Juliusz Schauder Centre for Nonlinear Studies, 2014)We are concerned here with the classical problem of Poincaré of persistence of periodic solutions under small perturbations. The main contribution of this work is to give the expression of the second order bifurcation ... 
Perturbed rank 2 Poisson systems and periodic orbits on Casimir invariant manifolds
(Taylor & Francis, 20200205)A class of ndimensional Poisson systems reducible to an unperturbed harmonic oscillator shall be considered. In such case, perturbations leaving invariant a given symplectic leaf shall be investigated. Our purpose will ... 
Polynomial and rational first integrals for planar homogeneous polynomial differential systems
(Universitat Autònoma de Barcelona, 2014)In this paper we find necessary and suficient conditions in order that a planar homogeneous polynomial differential system has a polynomial or rational first integral. We apply these conditions to linear and quadratic ... 
Polynomial and rational first integrals for planar quasihomogeneous polynomial differential systems
(American Institute of Mathematical Sciences, 201310)In this paper we find necessary and sufficient conditions in order that a planar quasihomogeneous polynomial differential system has a polynomial or a rational first integral. We also prove that any planar quasihomogeneous ... 
Population Dynamics P system (PDP) models: a standarized protocol for describing and applying novel bioinspires computing tools
(Public Library of Science (PLoS), 2013)Today, the volume of data and knowledge of processes necessitates more complex models that integrate all available information. This handicap has been solved thanks to the technological advances in both software and hardware. ... 
Properties of mixed Moore graphs of directed degree one
(Elsevier, 20150401)Mixed graphs of order n such that for any pair of vertices there is a unique trail of length at most k between them are known as mixed Moore graphs. These extremal graphs may only exist for diameter k = 2 and certain ...