UAB Digital Repository of Documents 13 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
1.
29 p, 5.8 MB Zero--Hopf bifurcations in 3-dimensional differential systems with no equilibria / Cândido, Murilo R. (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques)
We use averaging theory for studying the Hopf and zero--Hopf bifurcations in some chaotic differential systems. These differential systems have a chaotic attractor and no equilibria. Numerically we show the relation between the existence of the periodic solutions studied in these systems and their chaotic attractors.
2018 - 10.1016/j.matcom.2018.03.008
Mathematics and computers in simulation, Vol. 151 (Sep. 2018) , p. 54-76  
2.
29 p, 409.2 KB Polynomial Hamiltonian systems of degree 3 with symmetric nilpotent centers / Dias, Fabio Scalco (Universidade Federal de Itajubá(Brazil). Instituto de Matemática e Computacâo) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Valls, Clàudia (Universidade de Lisboa. Departamento de Matemàtica)
We provide normal forms and the global phase portraits in the Poincaré disk for all Hamiltonian planar polynomial vector fields of degree 3 symmetric with respect to the x-axis having a nilpotent center at the origin.
2018 - 10.1016/j.matcom.2017.06.002
Mathematics and computers in simulation, Vol. 144 (Feb. 2018) , p. 60-77  
3.
31 p, 953.6 KB Spherical microaggregation : anonymizing sparse vector spaces / Abril Castellano, Daniel (Institut d'Investigació en Intel·ligència Artificial) ; Navarro-Arribas, Guillermo (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Torra i Reventós, Vicenç (Institut d'Investigació en Intel·ligència Artificial)
Unstructured texts are a very popular data type and still widely unexplored in the privacy preserving data mining field. We consider the problem of providing public information about a set of confidential documents. [...]
2015 - 10.1016/j.cose.2014.11.005
Computers & Security, Vol. 49 (March 2015) , p. 28-44  
4.
9 p, 1.1 MB A comprehensive open package format for preservation and distribution of geospatial data and metadata / Pons, Xavier (Universitat Autònoma de Barcelona. Departament de Geografia) ; Masó Pau, Joan (Centre de Recerca Ecològica i Aplicacions Forestals)
The complexities of the intricate geospatial resources and formats make preservation and distribution of GIS data difficult even among experts. The proliferation of, for instance, KML, Internet map services, etc, reflects the need for sharing geodata but a comprehensive solution when having to deal with data and metadata of a certain complexity is not currently provided. [...]
2017 - 10.1016/j.cageo.2016.09.001
Computers & Geosciences, Vol. 97 (Dec. 2016) , p. 89-97  
5.
50 p, 374.9 KB Limit cycles bifurcating from a degenerate center / Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Pantazi, Chara (Universitat Politècnica de Catalunya. Departament de Matemàtica Aplicada I)
We study the maximum number of limit cycles that can bifurcate from a degenerate center of a cubic homogeneous polynomial differential system. Using the averaging method of second order and perturbing inside the class of all cubic polynomial differential systems we prove that at most three limit cycles can bifurcate from the degenerate center. [...]
2016 - 10.1016/j.matcom.2015.05.005
Mathematics and Computers in Simulation, Vol. 120 (2016) , p. 1-11  
6.
46 p, 1.8 MB Development and economic assessment of different WWTP control strategies for optimal simultaneous removal of carbon, nitrogen and phosphorus / Simion Ostace, George (Babes-Bolyai University. Department of Chemical Engineering) ; Baeza Labat, Juan Antonio (Universitat Autònoma de Barcelona. Departament d’Enginyeria Química, Biològica i Ambiental) ; Guerrero Camacho, Francisco Javier (Universitat Autònoma de Barcelona. Departament d’Enginyeria Química) ; Guisasola Canudas, Albert (Universitat Autònoma de Barcelona. Departament d’Enginyeria Química, Biològica i Ambiental) ; Cristea, Vasile Mircea (Babes-Bolyai University. Department of Chemical Engineering) ; Agachi, Paul Serban (Babes-Bolyai University. Department of Chemical Engineering) ; Lafuente Sancho, Francisco Javier (Universitat Autònoma de Barcelona. Departament d’Enginyeria Química, Biològica i Ambiental)
This paper presents the comparison of four control strategies for the A²/O WWTP configuration for simultaneous C, N and P removal. The control strategies: (i) external COD-P control; (ii) external recycle flow-P control; (iii) nitrate control in the last anoxic reactor; (iv) ammonia control in the last aerobic reactor, were combined with other common control loops to build different control structures and were simulated in Matlab/Simulink under different influent conditions. [...]
2013 - 10.1016/j.compchemeng.2013.03.007
Computers and chemical engineering, Vol. 53 (June 2013) , p. 164-177  
7.
12 p, 272.4 KB Piecewise linear differential systems with two real saddles / Artés, Joan Carles (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Medrado, Joao Carlos (Universidade Federal de Goiás(Brazil).Instituto de Matemática e Estatística) ; Teixeira, Marco Antonio (Universidade Estadual de Campinas(Brazil). Departamento de Matemática)
In this paper we study piecewise linear differential systems formed by two regions separated by a straight line so that each system has a real saddle point in its region of definition. If both saddles are conveniently situated, they produce a transition flow from a segment of the splitting line to another segment of the same line, and this produces a generalized singular point on the line. [...]
2013 - 10.1016/j.matcom.2013.02.007
Mathematics and Computers in Simulation, Vol. 95 (2013) , p. 13-22  
8.
19 p, 311.7 KB Center conditions and cyclicity for a family of cubic systems: computer algebra approach / Fercec, Brigita (University of Maribor(Slovenia).Center for Applied Mathematics and Theoretical Physics) ; Mahdi, Adam (University of North Carolina at Charlotte. Mathematics Department)
Using methods of computational algebra we obtain an upper bound for the cyclicity of a family of cubic systems. To that end we overcome the problem of nonradicality of the associated Bautin ideal by moving from the ring of polynomials to a coordinate ring. [...]
2013 - 10.1016/j.matcom.2013.02.003
Mathematics and Computers in Simulation, Vol. 87 (2013) , p. 55-67  
9.
26 p, 748.4 KB On the Darboux integrability of Blasius and Falkner-Skan equation / Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Valls, Clàudia (Universidade Técnica de Lisboa. Departamento de Matemática)
We study the Darboux integrability of the celebrated Falkner–Skan equation f′′′ + ff′′ + λ(1−f′2) = 0, where λ is a parameter. When λ = 0 this equation is known as Blasius equation. [...]
2013 - 10.1016/j.compfluid.2013.06.027
Computers & Fluids, Vol. 86 (2013) , p. 71-76  
10.
10 p, 682.0 KB On the C^1 non-integrability of the Belousov-Zhabotinskii system / Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Valls, Clàudia (Universidade Técnica de Lisboa. Departamento de Matemática)
2011 - 10.1016/j.camwa.2011.07.021
Computers & Mathematics with Applications. An International Journal, Vol. 62 (2011) , p. 2342-2348  

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