Browsing by Subject "Equacions diferencials ordinàries"
Now showing items 120 of 96

A chaotic secure communication scheme based on duffing oscillators and frequency estimation
(2013)
Conference report
Open AccessThis work presents a new technique to securely transmit and retrieve a message signal via chaotic systems. In our system, a twovalued message signal modulates the frequency of a Duffing oscillator sinusoidal term. An ... 
A characterization of isochronous centres in terms of symmetries
(2000)
Article
Open AccessWe present a description of isochronous centres of planar vector fields $X$ by means of their groups of symmetries. More precisely, given a normalizer $U$ of $X$ (i.e., $[X,U]=\mu X$, where $\mu$ is a scalar function), we ... 
A computational and geometric approach to phase resetting curves and surfaces
(2009)
Article
Open Access 
Adaptive backstepping control of a class of hysteretic systems
(SPIE Press. The International Society for Optical Engineering, 20030801)
Part of book or chapter of book
Open AccessA backsteppingbased adaptive control is designed for a class of one degree of freedom hysteretic system. The true hysteretic behavior does not need to be known for the controller design. A polynomial description is assumed ... 
Adiabatic invariant of the harmonic oscillator, complex matching and resurgence
(1997)
Article
Open AccessThe linear oscillator equation with a frequency depending slowly on time is used to test a method to compute exponentially small quantities. This work present the matching method in the complex plane as a tool to obtain ... 
A logistic queue model for network traffic modeling and simulation
(Universitat Politècnica de Catalunya, 201707)
Master thesis
Open AccessIn this work we present a continuous queuing model called the logistic queue model. We show that in terms of queue size and outflow prediction, our model is as precise as a discrete event simulator with the additional ... 
An analyticnumerical method of computation of the Liapunov and period constants derived from their algebraic structure
(1996)
Article
Open AccessWe consider the problem of computing the Liapunov and the period constants for a smooth differential equation with a non degenerate critical point. First, we investigate the structure of both constants when they are ... 
A new algorithm for finding rational first integrals of polynomial vector fields
(200905)
External research report
Open AccessWe present a new method to compute rational first integrals of a planar polynomial vector field. The algorithm is in general much faster than the usual methods and also allows to compute the remarkable curves associated ... 
An explicit expression of the first Liapunov and period constants with applications
(1996)
Article
Open AccessIn this paper, we study systems in the plane having a critical point with pure imaginary eigenvalues, and we search for effective conditions to discern whether this critical point is a focus or a center; in the case of it ... 
A pseudonormal form for planar vector fields
(2001)
Article
Open Access 
Bifurcation at complex instability
(1995)
Article
Open AccessIn an autonomous Hamiltonian system with three or more degrees of freedom, a family of periodic orbits may become unstable when two pairs of characteristic multipliers coallesce on the unit circle at points not equal to ... 
Boundary value problems for Schrödinger operators on a Path Associated to Orthogonal Polynomials
(Springer, 2013)
Part of book or chapter of book
Restricted access  publisher's policyIn this work, we concentrate on determining explicit expressions, via suitable orthogonal polynomials on the line, for the Green function associated with any regular boundary value problem on a weighted path, whose weights ... 
Bounded and dissipative solutions of the BoucWen model for hysteretic structural systems
(200406)
Part of book or chapter of book
Open AccessThe aim of this paper is to give the conditions on the hysteretic BoucWen model so that (i) it has the property of being bounded input bounded output (BIBO), and (ii) it dissipates energy (or is passive). This study leads ... 
Breakdown of heteroclinic orbits for analytic unfoldings of the hopfzero singularity. The singular case
(2011)
External research report
Open AccessIn this paper we prove the breakdown of an heteroclinic connection in the analytic versal unfoldings of the generic HopfZero singularity. This heteroclinic orbit appears at any order if one performs the normal form around ... 
Centers and uniform isochronous centers of planar polynomial differential systems
(201809)
Article
Restricted access  publisher's policyFor planar polynomial vector fields of the form (y+X(x,y))¿¿x+(x+Y(x,y))¿¿y, where X and Y start at least with terms of second order in the variables x and y, we determine necessary and sufficient conditions under which ... 
Centre and isochronicity conditions for systems with homogeneous nonlinearities
(1995)
Article
Open AccessWe study the centrefocus problem for systems with homogeneous nonlinearities. In the centre case we study the characterization of the isochronous centres. More explicitly, we derive six necessary conditions to be a ... 
Condiciones de contorno en modelos de gradiente con desplazamientos suavizados
(2012)
Article
Open AccessLos modelos de gradiente basados en desplazamientos suavizados son una alternativa a los modelos est´andares para simular num´ericamente el proceso de fallo de materiales. En esta formulaci´on alternativa coexisten los ... 
Constraint algorithm for extremals in optimal control problems
(20070727)
Article
Open AccessA characterization of different kinds of extremals of optimal control problems is given if we take an open control set. A well known constraint algorithm for implicit differential equations is adapted to the study of ... 
Continua of periodic points for planar integrable rational maps
(Research India Publications, 201609)
Article
Open AccessWe present three alternative methodologies to find continua of periodic points with a prescribed period for rational maps having rational first integrals. The first two have been already used by other authors and apply ... 
Continua of periodic points for planar integrable rational maps.
(20151130)
External research report
Open AccessWe present three alternative methodologies to find continua of periodic points with a prescribed period for rational maps having rational first integrals. The first two have been already used for other authors and apply ...