Departaments de Matemàtica Aplicada
http://hdl.handle.net/2117/3917
2015-07-29T00:45:24ZPrácticas complementarias al curso de Matemáticas II al tema de las derivadas parciales: Procesamiento digital de imágenes
http://hdl.handle.net/2117/76336
Prácticas complementarias al curso de Matemáticas II al tema de las derivadas parciales: Procesamiento digital de imágenes
Acho Zuppa, Leonardo
Documento docente sobre algunas aplicaciones de las derivadas parciales al procesamiento digital de imágenes.
Documento docente sobre algunas aplicaciones de las derivadas parciales al procesamiento digital de imágenes.
2015-04-08T00:00:00ZControl difuso para el seguimiento de guiñada del AUV Cormorán
http://hdl.handle.net/2117/76334
Control difuso para el seguimiento de guiñada del AUV Cormorán
González Agudelo, Julián; Gomáriz Castro, Spartacus; Batlle Arnau, Carles
2015-03-31T00:00:00ZAsymetric modelling and control of an electronic throttle
http://hdl.handle.net/2117/76224
Asymetric modelling and control of an electronic throttle
Pujol Vázquez, Gisela; Vidal Seguí, Yolanda; Acho Zuppa, Leonardo; Vargas, Alessandro N.
This paper presents an improved model for an automotive electronic throttle inspired on the behavior observed in real-time experiments. Due to a number of issues, particularly the return-spring, the performance of the throttle valve depends on whether it is opening or closing. This asymmetric behavior was taken into account to design a mathematical model of the throttle body and to derive a nonlinear asymmetric
PI controller. The experimental demonstration suggests that considering an asymmetric term dramatically improves the performance of the controller
This is the peer reviewed version of the following article: Pujol, G., Vidal, Y., Acho, L. and Vargas, A. N. (2015), Asymmetric modelling and control of an electronic throttle. Int. J. Numer. Model, which has been published in final form at http://dx.doi.org/10.1002/jnm.2063. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
2015-04-20T00:00:00ZSet-membership parity space approach for fault detection in linear uncertain dynamic systems
http://hdl.handle.net/2117/76223
Set-membership parity space approach for fault detection in linear uncertain dynamic systems
Blesa Izquierdo, Joaquim; Puig Cayuela, Vicenç; Saludes Closa, Jordi; Fernández Canti, Rosa M.
In this paper, a set-membership parity space approach for linear uncertain dynamic systems is proposed. First, a set of parity relations derived from the parity space approach is obtained by means of a transformation derived from the system characteristic polynomial. As a result of this transformation, parity relations can be expressed in regressor form. On the one hand, this facilitates the parameter estimation of those relations using a zonotopic set-membership algorithm. On the other hand, fault detection is then based on checking, at every sample time, the non-existence of a parameter value in the parameter uncertainty set such that the model is consistent with all the system measurements. The proposed approach is applied to two examples: a first illustrative case study based on a two-tank system and a more realistic case study based on the wind turbine fault detection and isolation benchmark in order to evaluate its effectiveness
2014-03-11T00:00:00ZOn the time decay of solutions in micropolar viscoelasticity
http://hdl.handle.net/2117/76207
On the time decay of solutions in micropolar viscoelasticity
Leseduarte Milán, María Carme; Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
This paper deals with isotropic micropolar viscoelastic materials.
It can be said that that kind of materials have two internal structures: the
macrostructure, where the elasticity effects are noticed, and the microstructure,
where the polarity of the material points allows them to rotate. We introduce,
step by step, dissipation mechanisms in both structures, obtain the corresponding
system of equations and determine the behavior of its solutions with respect the
time.
The final publication is available at Springer via http://dx.doi.org/10.1007/s11012-015-0117-0
2015-07-01T00:00:00ZNonsingular isogeometric boundary element method for stokes flows in 3D
http://hdl.handle.net/2117/28558
Nonsingular isogeometric boundary element method for stokes flows in 3D
Heltai, Luca; Arroyo Balaguer, Marino; DeSimone, Antonio
Isogeometric analysis (IGA) is emerging as a technology bridging computer aided geometric design (CAGD), most commonly based on Non-Uniform Rational B-Splines (NURBS) surfaces, and engineering analysis. In finite element and boundary element isogeometric methods (FE-IGA and IGA-BEM), the NURBS basis functions that describe the geometry define also the approximation spaces. In the FE-IGA approach, the surfaces generated by the CAGD tools need to be extended to volumetric descriptions, a major open problem in 3D. This additional passage can be avoided in principle when the partial differential equations to be solved admit a formulation in terms of boundary integral equations, leading to boundary element isogeometric analysis (IGA-BEM). The main advantages of such an approach are given by the dimensionality reduction of the problem (from volumetric-based to surface-based), by the fact that the interface with CAGD tools is direct, and by the possibility to treat exterior problems, where the computational domain is infinite. By contrast, these methods produce system matrices which are full, and require the integration of singular kernels. In this paper we address the second point and propose a nonsingular formulation of IGA-BEM for 3D Stokes flows, whose convergence is carefully tested numerically. Standard Gaussian quadrature rules suffice to integrate the boundary integral equations, and carefully chosen known exact solutions of the interior Stokes problem are used to correct the resulting matrices, extending the work by Klaseboer et al. (2012) [27] to IGA-BEM.
2014-01-01T00:00:00ZDistance-regular graphs where the distance-d graph has fewer distinct eigenvalues
http://hdl.handle.net/2117/28555
Distance-regular graphs where the distance-d graph has fewer distinct eigenvalues
Fiol Mora, Miquel Àngel; Brouwer, Andries
Let the Kneser graph K of a distance-regular graph $\Gamma$ be the graph on
the same vertex set as $\Gamma$, where two vertices are adjacent when they have
maximal distance in $\Gamma$. We study the situation where the Bose-Mesner
algebra of $\Gamma$ is not generated by the adjacency matrix of K. In particular,
we obtain strong results in the so-called `half antipodal' case.
2015-01-01T00:00:00ZHybridizable Discontinuous Galerkin with degree adaptivity for the incompressible Navier-Stokes equations
http://hdl.handle.net/2117/28520
Hybridizable Discontinuous Galerkin with degree adaptivity for the incompressible Navier-Stokes equations
Giorgiani, Giorgio; Fernandez Mendez, Sonia; Huerta, Antonio
A degree adaptive Hybridizable Discontinuous Galerkin (HDG) method for the solution of the incompressible Navier-Stokes equations is presented. The key ingredient is an accurate and computationally inexpensive a posteriori error estimator based on the super-convergence properties of HDG. The error estimator drives the local modification of the approximation degree in the elements and faces of the mesh, aimed at obtaining a uniform error distribution below a user-given tolerance in a given output of interest. Three 2D numerical examples are presented. High efficiency of the proposed error estimator is found, and an important reduction of the computational effort is shown with respect to non-adaptive computations, both for steady state and transient simulations. (C) 2014 Published by Elsevier Ltd.
2014-07-02T00:00:00ZForce transduction and lipid binding in MscL: a continuum-molecular approach
http://hdl.handle.net/2117/28519
Force transduction and lipid binding in MscL: a continuum-molecular approach
Vanegas, Juan Manuel; Arroyo Balaguer, Marino
The bacterial mechanosensitive channel MscL, a small protein mainly activated by membrane tension, is a central model system to study the transduction of mechanical stimuli into chemical signals. Mutagenic studies suggest that MscL gating strongly depends on both intra-protein and interfacial lipid-protein interactions. However, there is a gap between this detailed chemical information and current mechanical models of MscL gating. Here, we investigate the MscL bilayer-protein interface through molecular dynamics simulations, and take a combined continuum-molecular approach to connect chemistry and mechanics. We quantify the effect of membrane tension on the forces acting on the surface of the channel, and identify interactions that may be critical in the force transduction between the membrane and MscL. We find that the local stress distribution on the protein surface is largely asymmetric, particularly under tension, with the cytoplasmic side showing significantly larger and more localized forces, which pull the protein radially outward. The molecular interactions that mediate this behavior arise from hydrogen bonds between the electronegative oxygens in the lipid headgroup and a cluster of positively charged lysine residues on the amphipathic S1 domain and the C-terminal end of the second trans-membrane helix. We take advantage of this strong interaction (estimated to be 10-13 kT per lipid) to actuate the channel (by applying forces on protein-bound lipids) and explore its sensitivity to the pulling magnitude and direction. We conclude by highlighting the simple motif that confers MscL with strong anchoring to the bilayer, and its presence in various integral membrane proteins including the human mechanosensitive channel K2P1 and bovine rhodopsin.
2014-12-01T00:00:00ZError assessment in structural transient dynamics
http://hdl.handle.net/2117/28506
Error assessment in structural transient dynamics
Verdugo Rojano, Francesc; Parés Mariné, Núria; Díez, Pedro
This paper presents in a unified framework the most representative state-of-the-art techniques on a posteriori error assessment for second order hyperbolic problems, i.e., structural transient dynamics. For the sake of presentation, the error estimates are grouped in four types: recovery-based estimates, the dual weighted residual method, the constitutive relation error method and error estimates for timeline-dependent quantities of interest. All these methodologies give a comprehensive overview on the available error assessment techniques in structural dynamics, both for energy-like and goal-oriented estimates.
2014-03-01T00:00:00Z