http://hdl.handle.net/2117/3227 Tue, 21 May 2013 08:37:23 GMT 2013-05-21T08:37:23Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19118 Title: Random test examples with known minimum for convex semi-infinite programming problems Authors: Ferrer Biosca, Alberto; Miranda Galcerán, Eva Abstract: A signi cant research activity has occurred in the area of convex semi- in nite optimization in the recent years. Many new theoretical, algorithm and computational contribution has been obtained . Despite these numerous con- tributions, there still exits a lack of representative convex semi-in nite test problems. Test problems are of major importance for researchers interested in the algorithmic development. This article is motivated by the scarcity of con- vex semi-in nite test problems and describes a procedure for generating convex semi-in nite families of test problems with optimal solution and optimal value known. Tue, 07 May 2013 11:19:15 GMT http://hdl.handle.net/2117/19118 2013-05-07T11:19:15Z Ferrer Biosca, Alberto; Miranda Galcerán, Eva no A signi cant research activity has occurred in the area of convex semi- in nite optimization in the recent years. Many new theoretical, algorithm and computational contribution has been obtained . Despite these numerous con- tributions, there still exits a lack of representative convex semi-in nite test problems. Test problems are of major importance for researchers interested in the algorithmic development. This article is motivated by the scarcity of con- vex semi-in nite test problems and describes a procedure for generating convex semi-in nite families of test problems with optimal solution and optimal value known. http://hdl.handle.net/2117/18778 Title: Alternative tests for functional and pointwise output-controllability of linear time-invariant systems Authors: García Planas, María Isabel; Domínguez García, José Luis Abstract: This paper deals with the description of a new method for calculating the functional output-controllability. It is computed by means of the rank of a certain constant matrix which can be associated to the system. Moreover, a new method for the pointwise output-controllability determination by means of constructing the output-controllability matrix associated to the system using the residues of the given linear system is developed. Finally, a simple physical example is presented Fri, 12 Apr 2013 10:12:39 GMT http://hdl.handle.net/2117/18778 2013-04-12T10:12:39Z García Planas, María Isabel; Domínguez García, José Luis no This paper deals with the description of a new method for calculating the functional output-controllability. It is computed by means of the rank of a certain constant matrix which can be associated to the system. Moreover, a new method for the pointwise output-controllability determination by means of constructing the output-controllability matrix associated to the system using the residues of the given linear system is developed. Finally, a simple physical example is presented http://hdl.handle.net/2117/18733 Title: Nonsingular models of universes in teleparallel theories Authors: Haro Cases, Jaume; Amorós Torrent, Jaume Abstract: Different models of universes are considered in the context of teleparallel theories. Assuming that the universe is filled by a fluid with an equation of state P ¼ f ð Þ , for different teleparallel theories and different equation of state we study its dynamics. Two particular cases are studied in detail: in the first one we consider a function f with two zeros (two de Sitter solutions) that mimics a huge cosmological constant at early times and a pressureless fluid at late times; in the second one, in the context of loop quantum cosmology with a small cosmological constant, we consider a pressureless fluid ( P ¼ 0 , f ð Þ¼ ) which means there are de Sitter and anti–de Sitter solutions. In both cases one obtains a nonsingular universe that at early times is in an inflationary phase; after leaving this phase, it passes trough a matter dominated phase and finally at late times it expands in an accelerated way Description: PACS Numbers: 04.50.Kd, 98.80.Jk Tue, 09 Apr 2013 11:50:58 GMT http://hdl.handle.net/2117/18733 2013-04-09T11:50:58Z Haro Cases, Jaume; Amorós Torrent, Jaume no Cosmological constants, Equation of state, Loop quantum cosmologies, Nonsingular, Pressureless, Teleparallel theory Different models of universes are considered in the context of teleparallel theories. Assuming that the universe is filled by a fluid with an equation of state P ¼ f ð Þ , for different teleparallel theories and different equation of state we study its dynamics. Two particular cases are studied in detail: in the first one we consider a function f with two zeros (two de Sitter solutions) that mimics a huge cosmological constant at early times and a pressureless fluid at late times; in the second one, in the context of loop quantum cosmology with a small cosmological constant, we consider a pressureless fluid ( P ¼ 0 , f ð Þ¼ ) which means there are de Sitter and anti–de Sitter solutions. In both cases one obtains a nonsingular universe that at early times is in an inflationary phase; after leaving this phase, it passes trough a matter dominated phase and finally at late times it expands in an accelerated way http://hdl.handle.net/2117/18256 Title: Convolutional codes under control theory point of view. Analysis of output-observability Authors: García Planas, María Isabel; Souidi, El Mamoun; Um, Laurence E. Abstract: In this work we make a detailed look at the algebraic structure of convolutional codes using techniques of linear systems theory. The connection between these concepts help to better understand the properties of convo- lutional codes, in particular the concepts of controllability and observability of linear systems can be translated into the context of convolutional codes relating these properties with the noncatastrophicity of the codes. We examine the output-observability property and we give conditions for this property. Wed, 13 Mar 2013 12:48:29 GMT http://hdl.handle.net/2117/18256 2013-03-13T12:48:29Z García Planas, María Isabel; Souidi, El Mamoun; Um, Laurence E. no In this work we make a detailed look at the algebraic structure of convolutional codes using techniques of linear systems theory. The connection between these concepts help to better understand the properties of convo- lutional codes, in particular the concepts of controllability and observability of linear systems can be translated into the context of convolutional codes relating these properties with the noncatastrophicity of the codes. We examine the output-observability property and we give conditions for this property. http://hdl.handle.net/2117/18173 Title: Notas sobre análisis matemático para la ingeniería Authors: García Planas, María Isabel Mon, 11 Mar 2013 12:44:27 GMT http://hdl.handle.net/2117/18173 2013-03-11T12:44:27Z García Planas, María Isabel no http://hdl.handle.net/2117/18166 Title: Stability of a pipeline hydraulic fluid with one end fixed Authors: García Planas, María Isabel; Mediano Valiente, Begoña Abstract: The dynamics and stability of pipes conveying fluid has been studied thoroughly in the last decades. In this paper we study the stability in the Liapunov sense, of a clamped-pinned pipe conveying fluid at a low speed. After describing the motion of the system by partial differential equations we solve equations using finite element method testing solutions by means of ANSYS, we analyze the characteristic equation and its eigenvalues in order to obtain the stability conditions Mon, 11 Mar 2013 10:51:41 GMT http://hdl.handle.net/2117/18166 2013-03-11T10:51:41Z García Planas, María Isabel; Mediano Valiente, Begoña no The dynamics and stability of pipes conveying fluid has been studied thoroughly in the last decades. In this paper we study the stability in the Liapunov sense, of a clamped-pinned pipe conveying fluid at a low speed. After describing the motion of the system by partial differential equations we solve equations using finite element method testing solutions by means of ANSYS, we analyze the characteristic equation and its eigenvalues in order to obtain the stability conditions http://hdl.handle.net/2117/18162 Title: Factorization of the transfer matrix of a singular linear systems Authors: García Planas, María Isabel; López Cabeceira, M. Montserrat Abstract: Given a linear dynamic time invariant represented by x + ( t ) = Ax ( t ) Bu ( t ) , y ( t ) = Cx ( t ) , we analyze con- ditions for obtention of a coprime factorization of trans- fer matrices of singular linear systems defined over commutative rings R with element unit. The problem presented is related to the existence of solutions of a matrix equation XE ° NXA = Z . Mon, 11 Mar 2013 08:34:20 GMT http://hdl.handle.net/2117/18162 2013-03-11T08:34:20Z García Planas, María Isabel; López Cabeceira, M. Montserrat no Given a linear dynamic time invariant represented by x + ( t ) = Ax ( t ) Bu ( t ) , y ( t ) = Cx ( t ) , we analyze con- ditions for obtention of a coprime factorization of trans- fer matrices of singular linear systems defined over commutative rings R with element unit. The problem presented is related to the existence of solutions of a matrix equation XE ° NXA = Z . http://hdl.handle.net/2117/17957 Title: GenNon-h: Generating multiple sequence alignments on nonhomogeneous phylogenetic trees Authors: Kedzierska, A.M.; Casanellas Rius, Marta Abstract: Background: A number of software packages are available to generate DNA multiple sequence alignments (MSAs) evolved under continuous-time Markov processes on phylogenetic trees. On the other hand, methods of simulating the DNA MSA directly from the transition matrices do not exist. Moreover, existing software restricts to the time-reversible models and it is not optimized to generate nonhomogeneous data (i.e. placing distinct substitution rates at different lineages). Results: We present the first package designed to generate MSAs evolving under discrete-time Markov processes on phylogenetic trees, directly from probability substitution matrices. Based on the input model and a phylogenetic tree in the Newick format (with branch lengths measured as the expected number of substitutions per site), the algorithm produces DNA alignments of desired length. GenNon-h is publicly available for download. Conclusion: The software presented here is an efficient tool to generate DNA MSAs on a given phylogenetic tree. GenNon-h provides the user with the nonstationary or nonhomogeneous phylogenetic data that is well suited for testing complex biological hypotheses, exploring the limits of the reconstruction algorithms and their robustness to such models. Mon, 25 Feb 2013 12:43:58 GMT http://hdl.handle.net/2117/17957 2013-02-25T12:43:58Z Kedzierska, A.M.; Casanellas Rius, Marta no Background: A number of software packages are available to generate DNA multiple sequence alignments (MSAs) evolved under continuous-time Markov processes on phylogenetic trees. On the other hand, methods of simulating the DNA MSA directly from the transition matrices do not exist. Moreover, existing software restricts to the time-reversible models and it is not optimized to generate nonhomogeneous data (i.e. placing distinct substitution rates at different lineages). Results: We present the first package designed to generate MSAs evolving under discrete-time Markov processes on phylogenetic trees, directly from probability substitution matrices. Based on the input model and a phylogenetic tree in the Newick format (with branch lengths measured as the expected number of substitutions per site), the algorithm produces DNA alignments of desired length. GenNon-h is publicly available for download. Conclusion: The software presented here is an efficient tool to generate DNA MSAs on a given phylogenetic tree. GenNon-h provides the user with the nonstationary or nonhomogeneous phylogenetic data that is well suited for testing complex biological hypotheses, exploring the limits of the reconstruction algorithms and their robustness to such models. http://hdl.handle.net/2117/17931 Title: Some constructions for the fractional Laplacian on noncompact manifolds Authors: Banica, Valeria; González Nogueras, María del Mar; Sáez, Mariel Abstract: We give a de nition of the fractional Laplacian on some noncompact manifolds, through an extension problem introduced by Ca arelli-Silvestre. While this de nition in the compact case is straightforward, in the noncompact setting one needs to have a precise control of the behavior of the metric at in nity and geometry plays a crucial role. First we give explicit calculations in the hyperbolic space, including a formula for the kernel and a trace Sobolev inequality. Then we consider more general noncompact manifolds, where the problem reduces to obtain suitable upper bounds for the heat kernel. Fri, 22 Feb 2013 11:46:17 GMT http://hdl.handle.net/2117/17931 2013-02-22T11:46:17Z Banica, Valeria; González Nogueras, María del Mar; Sáez, Mariel no We give a de nition of the fractional Laplacian on some noncompact manifolds, through an extension problem introduced by Ca arelli-Silvestre. While this de nition in the compact case is straightforward, in the noncompact setting one needs to have a precise control of the behavior of the metric at in nity and geometry plays a crucial role. First we give explicit calculations in the hyperbolic space, including a formula for the kernel and a trace Sobolev inequality. Then we consider more general noncompact manifolds, where the problem reduces to obtain suitable upper bounds for the heat kernel. http://hdl.handle.net/2117/17905 Title: The equations of Rees algebras of equimultiple ideals of deviation one. Authors: Muiños, Ferran; Planas Vilanova, Francesc d'Assís Abstract: We describe the equations of the Rees algebra R(I) of an equimultiple ideal I of deviation one provided that I has a reduction generated by a regular sequence x1, . . . , xs such that the initial forms x∗ 1, . . . , x∗ s−1 are a regular sequence in the associated graded ring. In particular, we prove that there is a single equation of maximum degree in a minimal generating set of the equations of R(I), which recovers some previous known results. Thu, 21 Feb 2013 10:48:36 GMT http://hdl.handle.net/2117/17905 2013-02-21T10:48:36Z Muiños, Ferran; Planas Vilanova, Francesc d'Assís no We describe the equations of the Rees algebra R(I) of an equimultiple ideal I of deviation one provided that I has a reduction generated by a regular sequence x1, . . . , xs such that the initial forms x∗ 1, . . . , x∗ s−1 are a regular sequence in the associated graded ring. In particular, we prove that there is a single equation of maximum degree in a minimal generating set of the equations of R(I), which recovers some previous known results. http://hdl.handle.net/2117/17877 Title: On the ring of global sections of the blowing-up along a two-generated ideal. Authors: Giral, José M; Planas Vilanova, Francesc d'Assís Abstract: The effective relations and the relation type of an ideal generated by two regular elements can be expressed in terms of the ring of global sections of the blowing-up along the ideal. As a consequence, we find the minimal overring where the ideal is syzygetic or of linear type. Tue, 19 Feb 2013 12:19:04 GMT http://hdl.handle.net/2117/17877 2013-02-19T12:19:04Z Giral, José M; Planas Vilanova, Francesc d'Assís no The effective relations and the relation type of an ideal generated by two regular elements can be expressed in terms of the ring of global sections of the blowing-up along the ideal. As a consequence, we find the minimal overring where the ideal is syzygetic or of linear type. http://hdl.handle.net/2117/17875 Title: Special section on celestial mechanics and applications 3rd Conference on Nonlinear Science and Complexity 2010 – NSC10 Authors: Gidea, Marian; Masdemont Soler, Josep Tue, 19 Feb 2013 11:58:56 GMT http://hdl.handle.net/2117/17875 2013-02-19T11:58:56Z Gidea, Marian; Masdemont Soler, Josep no http://hdl.handle.net/2117/17874 Title: The space of phylogenetic mixtures for equivariant models Authors: Casanellas Rius, Marta; Fernández Sánchez, Jesús; Kedzierska, A.M. Abstract: The selection of the most suitable evolutionary model to analyze the given molecular data is usually left to biologist's choice. In his famous book, J Felsenstein suggested that certain linear equations satisfied by the expected probabilities of patterns observed at the leaves of a phylogenetic tree could be used for model selection. It remained open the question regarding whether these equations were enough for characterizing the evolutionary model. Here we prove that, for equivariant models of evolution, the space of distributions satisfying these linear equations coincides with the space of distributions arising from mixtures of trees on a set of taxa. In other words, we prove that an alignment is produced from a mixture of phylogenetic trees under an equivariant evolutionary model if and only if its distribution of column patterns satisfies the linear equations mentioned above. Moreover, for each equivariant model and for any number of taxa, we provide a set of linearly independent equations defining this space of phylogenetic mixtures. This is a powerful tool that has already been successfully used in model selection. We also use the results obtained to study identifiability issues for phylogenetic mixtures. Tue, 19 Feb 2013 11:45:51 GMT http://hdl.handle.net/2117/17874 2013-02-19T11:45:51Z Casanellas Rius, Marta; Fernández Sánchez, Jesús; Kedzierska, A.M. no The selection of the most suitable evolutionary model to analyze the given molecular data is usually left to biologist's choice. In his famous book, J Felsenstein suggested that certain linear equations satisfied by the expected probabilities of patterns observed at the leaves of a phylogenetic tree could be used for model selection. It remained open the question regarding whether these equations were enough for characterizing the evolutionary model. Here we prove that, for equivariant models of evolution, the space of distributions satisfying these linear equations coincides with the space of distributions arising from mixtures of trees on a set of taxa. In other words, we prove that an alignment is produced from a mixture of phylogenetic trees under an equivariant evolutionary model if and only if its distribution of column patterns satisfies the linear equations mentioned above. Moreover, for each equivariant model and for any number of taxa, we provide a set of linearly independent equations defining this space of phylogenetic mixtures. This is a powerful tool that has already been successfully used in model selection. We also use the results obtained to study identifiability issues for phylogenetic mixtures. http://hdl.handle.net/2117/17870 Title: Classi fication of monogenic invariant subspaces and uniparametric linear control systems Authors: Compta Creus, Albert; Ferrer Llop, Josep Abstract: The classification of the invariant subspaces of an endomorphism has been an open problem for a long time, and it is a ”wild” problem in the general case. Here we obtain a full classification for the monogenic ones. Some applications are derived: in particular, canonical forms for uniparametric linear control systems, non necessarily controllable, with regard to linear changes of state variables Tue, 19 Feb 2013 10:46:30 GMT http://hdl.handle.net/2117/17870 2013-02-19T10:46:30Z Compta Creus, Albert; Ferrer Llop, Josep no endomorphism, invariant subspaces, uniparametric control system, bimodal control system The classification of the invariant subspaces of an endomorphism has been an open problem for a long time, and it is a ”wild” problem in the general case. Here we obtain a full classification for the monogenic ones. Some applications are derived: in particular, canonical forms for uniparametric linear control systems, non necessarily controllable, with regard to linear changes of state variables http://hdl.handle.net/2117/17869 Title: Miniversal deformations of observable marked matrices Authors: Compta Creus, Albert; Ferrer Llop, Josep; Peña Carrera, Marta Abstract: Given the set of vertical pairs of matrices M¿ Mm,n(C)×Mn(C) keeping the subspace Cd×{0} ¿ Cn invariant, we compute miniversal deformations of a given pair when it is observable and the subspace Cd × {0} is marked. Moreover, we obtain the dimension of the orbit, characterize the structurally stable vertical pairs and study the effect of each deformation parameter. Tue, 19 Feb 2013 10:37:39 GMT http://hdl.handle.net/2117/17869 2013-02-19T10:37:39Z Compta Creus, Albert; Ferrer Llop, Josep; Peña Carrera, Marta no Conditioned invariant subspaces, Miniversal deformation, Stratified manifold, Vertical pairs of matrices Given the set of vertical pairs of matrices M¿ Mm,n(C)×Mn(C) keeping the subspace Cd×{0} ¿ Cn invariant, we compute miniversal deformations of a given pair when it is observable and the subspace Cd × {0} is marked. Moreover, we obtain the dimension of the orbit, characterize the structurally stable vertical pairs and study the effect of each deformation parameter.