http://hdl.handle.net/2117/3920 2013-06-19T13:48:14Z http://hdl.handle.net/2117/19298 Title: A phase-field fracture model of ferroelectric materials under electro-mechanical loading Authors: Abdollahi Hosnijeh, Amir; Arias Vicente, Irene Abstract: A phase-field model is proposed for the coupled simulation of microstructure and fracture evolution in ferroelectric materials. The model is based on energetic phase-field approaches for brittle fracture and ferroelectric domain formation and evolution. The variational nature of these approaches makes their coupling very natural. However the main challenge is to encode the electro-mechanical conditions of the sharp crack faces into the phase-field framework since the crack in this model is smeared and represented by an internal layer. We develope the model for different crack face boundary conditions. Simulations show the microstructure induced by the presence of the crack. Interactions between the microstructure and the crack are investigated under different electro-mechanical loadings. 2013-05-16T12:58:07Z http://hdl.handle.net/2117/19182 Title: Verbalització multilingüística del llenguatge simbòlic, una eina d'aprenentatge Authors: Alsina Aubach, Montserrat; Soler Lorente, Mónica 2013-05-13T14:46:06Z http://hdl.handle.net/2117/19012 Title: Aula virtual de apoyo a la docencia y al autoaprendizaje de cálculo para estudiantes universitarios con material docente y aplicaciones basadas en software libre Authors: Jarauta Bragulat, Eusebio; Pelayo Melero, Ignacio Manuel 2013-04-26T12:30:02Z http://hdl.handle.net/2117/18908 Title: Polynomials in finite geometries Authors: Ball, Simeon Michael Abstract: A method of using polynomials to describe objects in finite geometries is outlined and the problems where this method has led to a solution are surveyed. These problems concern nuclei, affine blocking sets, maximal arcs and unitals. In the case of nuclei these methods give lower bounds on the number of nuclei to a set of points in PG(n, q), usually dependent on some binomial coefficient not vanishing modulo the characteristic of the field. These lower bounds on nuclei lead directly to lower bounds on affine blocking sets with respect to lines. A short description of how linear polynomials can be used to construct maximal arcs in certain translation planes is included. A proof of the non-existence of maximal arcs in PG(2, q) when q is odd is outlined and some bounds are given as to when a (k, n)-arc can be extended to a maximal arc in PG(2, q). These methods can also be applied to unitals embedded in PG(2, q). One implication of this is that when q is the square of a prime a non-classical unital has a limited amount of Baer sublines amongst its secants. 2013-04-22T08:26:51Z http://hdl.handle.net/2117/18893 Title: Symplectic spreads and permutation polynomials Authors: Ball, Simeon Michael; Zieve, Michael Abstract: Every symplectic spread of PG(3, q), or equivalently every ovoid of Q(4, q), is shown to give a certain family of permutation polynomials of GF(q) and vice-versa. This leads to an algebraic proof of the existence of the Tits-L¨uneburg spread of W(22h+1) and the Ree-Tits spread of W(32h+1), as well as to a new family of low-degree permutation polynomials over GF(32h+1). 2013-04-19T12:30:37Z http://hdl.handle.net/2117/18891 Title: Commutative semifields of rank 2 over their middle nucleus Authors: Ball, Simeon Michael; Lavrauw, Michel Abstract: This article is about finite commutative semifields that are of rank 2 over their middle nucleus, the largest subset of elements that is a finite field. These semifields have a direct correspondence to certain flocks of the quadratic cone in PG(3, q) and to certain ovoids of the parabolic space Q(4, q). We shall consider these links, the known examples and non-existence results. 2013-04-19T12:12:41Z http://hdl.handle.net/2117/18704 Title: Improving symbolic language comprehension Authors: Alsina Aubach, Montserrat; Bonet Dalmau, Jordi Abstract: We focus on the goal of “Handling mathematical symbols and formalism” through the methodology of Content and Language Integrated Learning. The use of foreign language highlights, and possibly increases, the difficulties in the point of mathematical competence, but it can also be used to fix them. That is, making explicit the equivalence between formal and verbal language could improve symbolic language comprehension. Multilingual Formulae, an on -line resource at http://mformulae.epsem.upc.edu, is designed to give support in that direction, as equivalence is not found explicitly in textbooks or research papers. It contains sets of formulas with the corresponding written and oral version in several languages. The project, conducted by professors at the UPC Engineering School at Manresa Campus, is addressed to lecturers and students as a support to ensure effective communication when both Symbolic and Foreign language are used. 2013-04-08T13:31:02Z http://hdl.handle.net/2117/18608 Title: Locating a service facility and a rapid transit line Authors: Díaz Bañez, José Miguel; Korman Cozzetti, Matías; Pérez Lantero, Pablo; Ventura, Immaculada Abstract: In this paper we study a facility location problem in the plane in which a single point (facility) and a rapid transit line (highway) are simultaneously located in order to minimize the total travel time of the clients to the facility, using the L 1 or Manhattan metric. The rapid transit line is represented by a line segment with fixed length and arbitrary orientation. The highway is an alternative transportation system that can be used by the clients to reduce their travel time to the facility. This problem was introduced by Espejo and Rodríguez-Chía in [8]. They gave both a characterization of the optimal solutions and an algorithm running in O(n 3logn) time, where n represents the number of clients. In this paper we show that the Espejo and Rodríguez-Chía’s algorithm does not always work correctly. At the same time, we provide a proper characterization of the solutions with a simpler proof and give an algorithm solving the problem in O(n 3) time. 2013-04-04T11:31:06Z http://hdl.handle.net/2117/18607 Title: The 1-Center and 1-Highway Problem Authors: Díaz Bañez, José Miguel; Korman Cozzetti, Matías; Pérez Lantero, Pablo; Ventura, Immaculada Abstract: In this paper we extend the Rectilinear 1-center as follows: Given a set S of n points in the plane, we are interested in locating a facility point f and a rapid transit line (highway) H that together minimize the expression max p ∈ S d H (p,f), where d H (p,f) is the travel time between p and f. A point p ∈ S uses H to reach f if H saves time for p. We solve the problem in O(n 2) or O(nlogn) time, depending on whether or not the highway’s length is fixed. 2013-04-04T11:20:11Z http://hdl.handle.net/2117/18539 Title: Principal component analysis vs. independent component analysis for damage detection Authors: Tibaduiza Burgos, Diego Alexander; Mujica Delgado, Luis Eduardo; Anaya, Maribel; Rodellar Benedé, José; Güemes, Alfredo Abstract: In previous works, the authors showed advantages and drawbacks of the use of PCA and ICA by separately. In this paper, a comparison of results in the application of these methodologies is presented. Both of them exploit the advantage of using a piezoelectric active system in different phases. An initial baseline model for the undamaged structure is built applying each technique to the data collected by several experiments. The current structure (damaged or not) is subjected to the same experiments and the collected data are projected into the models. In order to determine whether damage exists or not in the structure, the projections into the first and second components using PCA and ICA are depicted graphically. A comparison between these plots is performed analyzing differences and similarities, advantages and drawbacks. To validate the approach, the methodology is applied in two sections of an aircraft wing skeleton powered with several PZTs transducers. 2013-04-02T11:18:26Z http://hdl.handle.net/2117/18506 Title: Future educators' explaning voices Authors: Minelli de Oliveira, Janaina; Buenestado Caballero, Pablo; Camacho, Mar Abstract: Teacher education programs must offer pre-service students innovative technology-supported learning environments, guiding them in the revision of their preconceptions on literacy and technology. This present paper presents a case study that uses podcast to inquiry into future educators’ views on technology and the digital age. Results show future educators present rather conservative views on technology use and few of them relate to the theme from their future professional identity. Courses aimed at preparing future educators to make pedagogical use of technology should explicitly address students’ preconceptions so as to favor the educational approaches required for the development of the twentieth century skills. 2013-03-26T12:15:43Z http://hdl.handle.net/2117/18480 Title: Plasmaspheric Electron Content contribution inferred from ground and radio occultation derived Total Electron Content Authors: Aragón Ángel, María Ángeles; Sanz Subirana, Jaume; Juan Zornoza, José Miguel; Hernández Pajares, Manuel; Altadill, D. Abstract: The FORMOSAT-3/COSMIC satellite constellation has become an important source of remote sensing data globally distributed for the sounding of the atmosphere of the Earth and, in particular, the ionosphere. In this study, electron density profiles derived using the Improved Abel transform inversion in Radio Occultation (RO) scenarios are used as input data to derive some features regarding the topside and outside ionospheric contribution, hence, the plasmasphere in great extend, by means of the analysis of the integral values of the shape functions corresponding to each density profile. The novelty presented in this paper, with respect to previous works, is the use of experimental data from the FORMOSAT-3/COSMIC RO-derived electron densities to infer global characterizations and distribution of the Total Electron Content (TEC) into its main components: ionospheric TEC and plasmaspheric TEC, both contributing to TEC. The results show agreement with earlier modeled and observational data from previous local studies of the plasmaspheric contribution. The main conclusion of this research is that the plasmasphere contributes significantly to TEC and the ratio between plasmaspheric TEC and TEC has been climatologically analyzed for the whole year 2007 confirming that the major relative impact of the plasmasphere is during night time. The added value of this study is that the results obtained are globally distributed and can help to infer a proxy for the plasmaspheric contribution at any location over the globe thanks to the FORMOSAT-3/COSMIC coverage. 2013-03-22T10:59:58Z http://hdl.handle.net/2117/18467 Title: Multivariable model predictive control of water levels on a laboratory canal Authors: Horvath, Klaudia; Van Overloop, P.J.; Galvis Restrepo, Eduard; Gómez Valentín, Manuel; Rodellar Benedé, José Abstract: Automatic control of irrigation canals can reduce the loss of water in considerable amounts, therefore it is generating ecologic and economic benefits. There have been many different types of automatic controllers developed, but only few of them had the opportunity of being tested on the field due to the long delay time and the inconveniences of interrupting the operation of the irrigation. Therefore, the automatic controllers developed for large irrigation canals should be tested before by means of numerical simulations and/or laboratory experiments. The Technical University of Catalonia possesses a laboratory irrigation canal with the length of 220m, with 3 motorized gates, and 11 level sensors that are connected to a SCADA system. This facility makes it possible to test controllers of any type, since all the instrumentation and real time operation runs within a flexible working environment running in Matlab-Simulink . The canal can be configured from one pool to three pools, which allows the development of multivariable control. A numerical model of the canal has been developed using the 1D hydrodynamic model SIC. With the help of this software it is possible to simulate the hydraulics of the canal and, due to the link between SIC and Matlab, also to test any controller developed previously in the Matlab environment. In this work a centralized multivariable model predictive controller for water levels is developed and validated by means of numerical simulation. 2013-03-22T09:16:04Z http://hdl.handle.net/2117/18452 Title: Clasificación de 3-semigrupos numéricos mediante L-formas Authors: Aguiló Gost, Francisco de Asis L.; Marijuan López, Carlos Abstract: Un semigrupo num erico generado por tres elementos tiene asociadas una o dos teselaciones peri odicas del plano generadas por una baldosa en forma de L. Se conocen algunas propiedades combinatorias del semigrupo en t erminos de las di- mensiones de dicha baldosa. Por otro lado, algunas clases de semigrupos num ericos se han utilizado en el estudio de singularidades de curvas, donde reciben el nombre de las clases de curvas asociadas. En este trabajo damos una caracterizaci on de las dimensiones de las baldosas asocidas a un 3-semigrupo num erico en t erminos de sus generadores y la utilizamos para clasi car los 3-semigrupos num ericos de inter es en geometr a. 2013-03-21T12:49:42Z http://hdl.handle.net/2117/18451 Title: Familias infinitas de digrafos de Cayley de grado 2 óptimos sobre grupos abelianos finitos Authors: Aguiló Gost, Francisco de Asis L.; Miralles de la Asunción, Alicia Abstract: Sea GN un grupo abeliano finito de orden N. Para cada conjunto de generadores f, g = GN, consideremos el digrafo de Cayley Cay(GN, {f, g}). Seg´un sea GN c´ıclico o no c´ıclico, podemos obtener un di´ametro ´optimo para Cay(GN, {f, g}). En este trabajo estudiamos esta cuesti´on usando diagramas de distancias m´ınimas asociados a estos digrafos. Tambi´en damos familias infinitas de digrafos ´optimos, tanto para GN c´ıclico como no c´ıclico. 2013-03-21T12:45:12Z