Browsing by Subject "Differential equations"
Now showing items 120 of 163

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 contribution to video coding using layers
(1998)
Conference report
Open AccessLayered representations of video sequences, originally introduced in [1], are important in several applications. Specifically, they are very appropriate for object tracking, object manipulation, contentbased scalability ... 
Actionangle variables and a KAM theorem for bPoisson manifolds
(20160101)
Article
Open AccessIn this article we prove an actionangle theorem for bintegrable systems on bPoisson manifolds improving the actionangle theorem contained in [14] for general Poisson manifolds in this setting. As an application, we ... 
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 discrete bernoulli free boundary problem
(201204)
External research report
Open AccessWe consider a free boundary problem for the pLaplace operator which is related to the socalled Bernoulli free boundary problem. In this formulation, the classical boundary gradient condition is replaced by a condition ... 
A Hamiltonian study of the stability and bifurcations for the satellite problem
(20151001)
Article
Open AccessWe study the dynamics of a rigid body in a central gravitational field modeled as a Hamiltonian system with continuous rotational symmetries following the geometric framework of Wang et al. Novelties of our work are the ... 
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 ... 
An efficient iterative method for computing deflections of Bernoulli–Euler–von Karman beams on a nonlinear elastic foundation
(20181001)
Article
Restricted access  publisher's policyAn efficient iterative method is developed for the static analysis of large deflections of an infinite beam with variable crosssection resting on a nonlinear foundation. A pseudo spring constant is added and explicit ... 
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 ... 
A new subdivision algorithm for the flow propagation using polynomial algebras
(20180801)
Article
Restricted access  publisher's policyThe Jet Transport method has emerged as a powerful tool for the numerical integration of ordinary differential equations; it uses polynomial expansions to approximate the flow map associated to the differential equation ... 
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 note on the symplectic topology of bmanifolds
(2017)
Article
Open AccessPoisson manifold (M2n; ) is bsymplectic if Vn is transverse to the zero section. In this paper we apply techniques native to Symplectic Topology to address questions pertaining to bsymplectic manifolds. We pro vide ... 
Aproximación del problema de Stokes mediante elementos finitos mixtos de tipo crossgrid
(2009)
Conference lecture
Restricted access  publisher's policyEn esta comunicación introducimos una familia de métodos de elementos finitos mixtos para la resolución numérica del problema de Stokes en dimensión 2. En estos métodos, la presión se interpola en una malla de elementos ... 
A pseudonormal form for planar vector fields
(2001)
Article
Open Access 
A singular initial value problem to construct densityequalizing maps
(201112)
Article
Restricted access  publisher's policyThe diffusionbased algorithm to produce densityequalizing maps interprets diffusion as an advection process. This algorithm uses the dynamics of a flow that is defined by an initial value problem that turns out to be ... 
A singular initial value problem to construct densityequalizing maps
(201105)
External research report
Open AccessThe diffusionbased algorithm to produce densityequalizing maps interprets diffusion as an advection process. This algorithm uses the dynamics of a flow that is defined by an initial value problem that turns out to be ... 
A smooth center manifold theorem which applies to some IIIposed partial differential equations with unbounded nonlinearities
(2009)
Article
Restricted access  publisher's policyWe prove the existence of a smooth center manifold for several partial differential equations, including ill posed equations with unbounded nonlinearities. We also prove smooth dependence on parameters with respect to ...