Now showing items 1-20 of 174

• #### A chaotic secure communication scheme based on duffing oscillators and frequency estimation ﻿

(2013)
Conference report
Open Access
This work presents a new technique to securely transmit and retrieve a message signal via chaotic systems. In our system, a two-valued message signal modulates the frequency of a Duffing oscillator sinusoidal term. An ...
• #### A characterization of isochronous centres in terms of symmetries ﻿

(2000)
Article
Open Access
We 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 Access
Layered representations of video sequences, originally introduced in [1], are important in several applications. Specifically, they are very appropriate for object tracking, object manipulation, content-based scalability ...
• #### A discrete bernoulli free boundary problem ﻿

(2012-04)
External research report
Open Access
We consider a free boundary problem for the p-Laplace operator which is related to the so-called 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 ﻿

(2015-10-01)
Article
Open Access
We 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, 2017-07)
Master thesis
Open Access
In 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 ...
• #### A new algorithm for finding rational first integrals of polynomial vector fields ﻿

(2009-05)
External research report
Open Access
We 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 ﻿

(2018-08-01)
Article
Open Access
The 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 ...
• #### A note on the symplectic topology of b-manifolds ﻿

(2017)
Article
Open Access
Poisson manifold (M2n; ) is b-symplectic if Vn is transverse to the zero section. In this paper we apply techniques native to Symplectic Topology to address questions pertaining to b-symplectic manifolds. We pro- vide ...
• #### A pseudo-normal form for planar vector fields ﻿

(2001)
Article
Open Access
• #### A singular initial value problem to construct density-equalizing maps ﻿

(2011-12)
Article
Restricted access - publisher's policy
The diffusion-based algorithm to produce density-equalizing 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 density-equalizing maps ﻿

(2011-05)
External research report
Open Access
The diffusion-based algorithm to produce density-equalizing 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 III-posed partial differential equations with unbounded nonlinearities ﻿

(2009)
Article
Restricted access - publisher's policy
We 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 ...
• #### A survey of the hysteretic Duhem model ﻿

(2018-11-01)
Article
Open Access
The Duhem model is a simulacrum of a com- plex and hazy reality: hysteresis. Introduced by Pierre Duhem to provide a mathematical representation of thermodynamical irreversibility, it is used to ...
• #### Action-angle variables and a KAM theorem for b-Poisson manifolds ﻿

(2016-01-01)
Article
Open Access
In this article we prove an action-angle theorem for b-integrable systems on b-Poisson manifolds improving the action-angle 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, 2003-08-01)
Part of book or chapter of book
Open Access
A backstepping-based 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 Access
The 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 ...
• #### An analytic-numerical method of computation of the Liapunov and period constants derived from their algebraic structure ﻿

(1996)
Article
Open Access
We 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 ﻿

(2018-10-01)
Article
Open Access
An efficient iterative method is developed for the static analysis of large deflections of an infinite beam with variable cross-section resting on a nonlinear foundation. A pseudo spring constant is added and explicit ...
• #### An explicit expression of the first Liapunov and period constants with applications ﻿

(1996)
Article
Open Access
In 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 ...