Resultats globals: 17 registres trobats en 0.02 segons.
Articles, 11 registres trobats
Llibres i col·leccions, 2 registres trobats
Documents de recerca, 4 registres trobats
Articles 11 registres trobats  1 - 10següent  anar al registre:
1.
Resonance of bounded isochronous oscillators / Rojas, David (Universitat de Girona. Departament d'Informàtica, Matemàtica Aplicada i Estadística)
An oscillator is called isochronous if all motions have a common period. When the system is forced by a time-dependent perturbation with the same period the phenomenon of resonance may appear. We give a sufficient condition on the perturbation in order that resonance occurs when the period annulus of the isochronous oscillator is bounded. [...]
2020 - 10.1016/j.na.2019.111680
Nonlinear Analysis: Theory, Methods and Applications, Vol. 192 (March 2020) , art. 111680  
2.
Bifurcation of relative equilibria generated by a circular vortex path in a circular domain / Rojas, David (Universitat de Girona. Departament d'Informàtica, Matemàtica Aplicada i Estadística) ; Torres, Pedro J. (Universidad de Granada. Departamento de Matemática Aplicada)
We study the passive particle transport generated by a circular vortex path in a 2D ideal flow confined in a circular domain. Taking the strength and angular velocity of the vortex path as main parameters, the bifurcation scheme of relative equilibria is identified. [...]
2020 - 10.3934/dcdsb.2019265
Discrete and continuous dynamical systems. Series B, Vol. 25, Issue 2 (February 2020) , p. 749-760  
3.
4 p, 314.0 KB The monotonicity of the apsidal angle using the theory of potential oscillators / Rojas, David (Universidad de Granada. Departamento de Matemática Aplicada)
In a central force system the angle between two successive passages of a body through pericenters is called the apsidal angle. In this paper we prove that for central forces of the form f(r)∼λr-(α+1) with α< 2 the apsidal angle is a monotonous function of the energy, or equivalently of the orbital eccentricity.
2018 - 10.1007/s12346-017-0265-9
Qualitative Theory of Dynamical Systems, Vol. 17, Issue 3 (October 2018) , p. 631-635  
4.
On the upper bound of the criticality of potential systems at the outer boundary using the Roussarie-Ecalle compensator / Rojas, David (Universitat Autònoma de Barcelona. Departament de Matemàtiques)
This paper is concerned with the study of the criticality of families of planar centers. More precisely, we study sufficient conditions to bound the number of critical periodic orbits that bifurcate from the outer boundary of the period annulus of potential centers. [...]
2019 - 10.1016/j.jde.2019.04.021
Journal of differential equations, Vol. 267, Issue 6 (September 2019) , p. 3922-3951  
5.
34 p, 632.0 KB Asymptotic Development of an Integral Operator and Boundedness of the Criticality of Potential Centers / Rojas, David (Universitat de Girona. Departament d'Informàtica, Matemàtica Aplicada i Estadística)
We study the asymptotic development at infinity of an integral operator. We use this development to give sufficient conditions to upper bound the number of critical periodic orbits that bifurcate from the outer boundary of the period function of planar potential centers. [...]
2019 - 10.1007/s10884-019-09753-2
Journal of dynamics and differential equations, (April 2019)  
6.
28 p, 445.8 KB Periodic oscillators, isochronous centers and resonance / Ortega, Rafael (Universidad de Granada. Departamento de Matemática Aplicada) ; Rojas, David (Universidad de Granada. Departamento de Matemática Aplicada)
An oscillator is called isochronous if all motions have a common period. When the system is forced by a time-dependent perturbation with the same period the dynamics may change and the phenomenon of resonance can appear. [...]
2019 - 10.1088/1361-6544/aaee9a
Nonlinearity, Vol. 32, Núm. 3 (March 2019) , p. 800-832  
7.
10 p, 362.5 KB A proof of Bertrand's theorem using the theory of isochronous potentials / Ortega, Rafael (Universidad de Granada. Departamento de Matemática Aplicada) ; Rojas, David (Universidad de Granada. Departamento de Matemática Aplicada)
We give an alternative proof for the celebrated Bertrand's theorem as a corollary of the isochronicity of a certain family of centers.
2018 - 10.1007/s10884-018-9676-9
Journal of dynamics and differential equations, Vol. 31, Issue 4 (December 2019) , p. 2017-2028  
8.
15 p, 468.0 KB A criticality result for polycycles in a family of quadratic reversible centers / Rojas, David (Universidad de Granada. Departamento de Matemática Aplicada) ; Villadelprat, Jordi (Universitat Rovira i Virgili. Departament d'Enginyeria Informàtica i Matemàtiques)
We consider the family of dehomogenized Loud's centers Xµ_=y(x-1)∂ₓ + (x + Dx² + Fy²)_y, where µ=(D,F)єR², and we study the number of critical periodic orbits that emerge or dissapear from the polycycle at the boundary of the period annulus. [...]
2018 - 10.1016/j.jde.2018.01.042
Journal of differential equations, Vol. 264, issue 11 (June 2018) , p. 6585-6602  
9.
23 p, 533.7 KB Analytic tools to bound the criticality at the outer boundary of the period annulus / Mañosas Capellades, Francesc (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Rojas, David (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Villadelprat, Jordi (Universitat Rovira i Virgili. Departament d'Enginyeria Informàtica i Matemàtiques)
In this paper we consider planar potential differential systems and we study the bifurcation of critical periodic orbits from the outer boundary of the period annulus of a center. In the literature the usual approach to tackle this problem is to obtain a uniform asymptotic expansion of the period function near the outer boundary. [...]
2018 - 10.1007/s10884-016-9559-x
Journal of dynamics and differential equations, Vol. 30, issue 3 (Sep. 2018) , p. 883-909  
10.
19 p, 504.7 KB Study of the period function of a two-parameter family of centers / Mañosas Capellades, Francesc (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Rojas, David (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Villadelprat, Jordi (Universitat Rovira i Virgili. Departament d'Enginyeria Informàtica i Matemàtiques)
In this paper we study the period function of ẍ = (1 x) p − (1 x) q , with p, q ∈ R and p > q. We prove three independent results. The first one establishes some regions in the parameter space where the corresponding center has a monotonous period function. [...]
2017 - 10.1016/j.jmaa.2017.02.054
Journal of mathematical analysis and applications, Vol. 452 (2017) , p. 188-208  

Articles : 11 registres trobats   1 - 10següent  anar al registre:
Llibres i col·leccions 2 registres trobats  
1.
Resonance of isochronous oscillators / Rojas, David (Universitat Rovira I Virgili. Departament D'Enginyeria Informàtica I Matemàtiques)
An oscillator such that all motions have the same minimal period is called isochronous. When the isochronous is forced by a time-dependent perturbation with the same natural frequency as the oscillator the phenomenon of resonance can appear. [...]
Cham, etc : Birkhäuser, cop. 2019 (Trends in mathematics. Research perspectives CRM Barcelona ; 11) - 10.1007/978-3-030-25261-8_13
Extended abstracts Spring 2018 : singularly perturbed systems, multiscale phenomena and hysteresis: theory and applications, 2019, p. 87-91  
2.
1 p, 80.8 KB Mercenario / Rojas Fernández, José David
Bellaterra : Universitat Autònoma de Barcelona. Escola d'Enginyeria, 2010  

Documents de recerca 4 registres trobats  
1.
142 p, 1.7 MB Analytical tools to study the criticality at the outer boundary of potential centers / Rojas Pérez, David ; Mañosas Capellades, Francesc, dir. (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Villadelprat Yagüe, Jordi, dir. ; Universitat Autònoma de Barcelona. Departament de Matemàtiques
[Barcelona] : Universitat Autònoma de Barcelona, 2016  
2.
68 p, 4.5 MB Study of the period function of a biparametric family of centers / Rojas Pérez, David ; Mañosas Capellades, Francesc, dir. (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Villadelprat, Jordi, dir. ; Universitat Autònoma de Barcelona. Departament de Matemàtiques
2013  
3.
142 p, 3.4 MB Extensions and applications of the Virtual Reference Feedback Tuning / Rojas Fernández, David ; Vilanova i Arbós, Ramon, dir. (Universitat Autònoma de Barcelona. Departament de Telecomunicació i Enginyeria de Sistemes) ; Universitat Autònoma de Barcelona. Departament de Telecomunicació i Enginyeria de Sistemes
En este trabajo, la técnica de control basada en datos "Virtual Reference Feedback Tuning" es tratada de diferentes maneras. Por un lado, las capacidades del método son extendidas con varias propuestas que permiten un uso más amplio del método. [...]
In this work the data-driven control technique "Virtual Reference Feedback Tuning" is treated in different ways. In one hand, the capabilities of the method are extended with several proposed variations that allow a wider use of the method. [...]

[Barcelona] : Universitat Autònoma de Barcelona, 2012  
4.
71 p, 1.3 MB Nuevos óxidos de Ag y Cu por intercalación electroquímica y otros métodos suaves : síntesis y caracterización de los sistemas Ag2Cu2O4+[delta] y Ag-Cu-M-O(M=Cr,Mn) / Muñoz Rojas, David ; Casañ Pastor, Nieves, dir. (Institut de Ciència de Materials de Barcelona)
With the aim of exchanging Hg by Ag in the copper-based superconductors with the highest Tc, the synthesis of simple Ag-Cu oxides (not known even in nature) became the first target. That work brought as a result the first known Ag-Cu oxide, Ag2Cu2O3, and also the second, Ag5Pb2-xCuxO6, both synthesized by soft chemistry methods (coprecipitation). [...]
En un intento de reemplazar Hg por Ag en los cupratos superconductores de mayor Tc, se abordó la síntesis de óxidos sencillos de Ag y Cu (inéditos incluso en la naturaleza). Ese trabajo dio como resultado el primer óxido de Ag y Cu conocido, Ag2Cu2O3, y el segundo, Ag5Pb2-xCuxO6, obtenidos por métodos suaves (coprecipitación ácido base). [...]

Bellaterra : Universitat Autònoma de Barcelona, 2004
4 documents

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