http://hdl.handle.net/2117/5340 Fri, 24 May 2013 16:03:21 GMT 2013-05-24T16:03:21Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19168 Title: Spectral properties of the connectivity matrix and the SIS-epidemic threshold for mid-size metapopulations Authors: Juher Barrot, David; Mañosa Fernández, Víctor Abstract: We consider the spread of an infectious disease on a heterogeneous metapopulation defined by any (correlated or uncorrelated) network. The infection evolves under transmission, recovering and migration mechanisms. We study some spectral properties of a connectivity matrix arising from the continuous-time equations of the model. In particular we show that the classical sufficient condition of instability for the disease-free equilibrium, well known for the particular case of uncorrelated networks, works also for the general case. We give also an alternative condition that yields a more accurate estimation of the epidemic threshold for correlated (either assortative or dissortative) networks Description: Preprint version of the paper Mon, 13 May 2013 08:19:06 GMT http://hdl.handle.net/2117/19168 2013-05-13T08:19:06Z Juher Barrot, David; Mañosa Fernández, Víctor no SIS epidemics, Complex networks, Spectral properties, Connectivity matrix, Disease-free equilibrium. We consider the spread of an infectious disease on a heterogeneous metapopulation defined by any (correlated or uncorrelated) network. The infection evolves under transmission, recovering and migration mechanisms. We study some spectral properties of a connectivity matrix arising from the continuous-time equations of the model. In particular we show that the classical sufficient condition of instability for the disease-free equilibrium, well known for the particular case of uncorrelated networks, works also for the general case. We give also an alternative condition that yields a more accurate estimation of the epidemic threshold for correlated (either assortative or dissortative) networks http://hdl.handle.net/2117/12720 Title: Non autonomous 2-periodic Gumovski-Mira difference equations Authors: Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor Abstract: We consider two types of non-autonomous 2-periodic Gumovski-Mira difference equations. We show that while the corresponding autonomous recurrences are conjugated, the behavior of the sequences generated by the 2-periodic ones di er dramatically: in one case the behavior of the sequences is simple (integrable) and in the other case it is much more complicated (chaotic). We also present a global study of the integrable case that includes which periods appear for the recurrence. Tue, 07 Jun 2011 11:53:42 GMT http://hdl.handle.net/2117/12720 2011-06-07T11:53:42Z Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor no Integrable and chaotic difference equations and maps, Rational difference equations with periodic coefficients, Perturbed twist maps We consider two types of non-autonomous 2-periodic Gumovski-Mira difference equations. We show that while the corresponding autonomous recurrences are conjugated, the behavior of the sequences generated by the 2-periodic ones di er dramatically: in one case the behavior of the sequences is simple (integrable) and in the other case it is much more complicated (chaotic). We also present a global study of the integrable case that includes which periods appear for the recurrence. http://hdl.handle.net/2117/12473 Title: The hydraulic influence matrix of opening gate trajectories in canals based on the method of characteristics: concept, compilation and practical examples Authors: Soler Guitart, Joan; Gómez, Manuel; Rodellar Benedé, José Thu, 05 May 2011 10:53:13 GMT http://hdl.handle.net/2117/12473 2011-05-05T10:53:13Z Soler Guitart, Joan; Gómez, Manuel; Rodellar Benedé, José no http://hdl.handle.net/2117/12085 Title: Desigualtats matricials útils en control robust Authors: Rubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria Abstract: En aquest treball presentem un recull de les desigualtats matricials més freqüentment utilitzades en el context del control robust amb possibles retardaments, a temps continu o discret. Juntament amb les demostracions de les desigualtats, també s'inclou una breu descripció d'altres materials d'interès, com són els complements de Schur i la fórmula de Sherman-Morrison-Woodbury. Fri, 25 Mar 2011 16:33:00 GMT http://hdl.handle.net/2117/12085 2011-03-25T16:33:00Z Rubió Massegú, Josep; Palacios Quiñonero, Francisco; Rossell Garriga, Josep Maria no En aquest treball presentem un recull de les desigualtats matricials més freqüentment utilitzades en el context del control robust amb possibles retardaments, a temps continu o discret. Juntament amb les demostracions de les desigualtats, també s'inclou una breu descripció d'altres materials d'interès, com són els complements de Schur i la fórmula de Sherman-Morrison-Woodbury. http://hdl.handle.net/2117/6893 Title: On two and three periodic Lyness difference equations Authors: Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor Abstract: We describe the sequences {x_n}_n given by the non-autonomous second order Lyness difference equations x_{n+2}=(a_n+x_{n+1})/x_n, where {a_n}_n is either a 2-periodic or a 3-periodic sequence of positive values and the initial conditions x_1,x_2 are as well positive. We also show an interesting phenomenon of the discrete dynamical systems associated to some of these difference equations: the existence of one oscillation of their associated rotation number functions. This behavior does not appear for the autonomous Lyness difference equations. Fri, 09 Apr 2010 11:12:00 GMT http://hdl.handle.net/2117/6893 2010-04-09T11:12:00Z Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor no Difference equations with periodic coefficients, Circle maps, Rotation number We describe the sequences {x_n}_n given by the non-autonomous second order Lyness difference equations x_{n+2}=(a_n+x_{n+1})/x_n, where {a_n}_n is either a 2-periodic or a 3-periodic sequence of positive values and the initial conditions x_1,x_2 are as well positive. We also show an interesting phenomenon of the discrete dynamical systems associated to some of these difference equations: the existence of one oscillation of their associated rotation number functions. This behavior does not appear for the autonomous Lyness difference equations.