Flow of magnetic repelling grains in a two-dimensional silo

During a typical silo discharge, the material flow rate is determined by the contact forces between the grains. Here, we report an original study concerning the discharge of a two-dimensional silo filled with repelling magnetic grains. This non-contact interaction leads to a different dynamics from the one observed with conventional granular materials. We found that, although the flow rate dependence on the aperture size follows roughly the power-law with an exponent $3/2$ found in non-repulsive systems, the density and velocity profiles during the discharge are totally different. New phenomena must be taken into account. Despite the absence of contacts, clogging and intermittence were also observed for apertures smaller than a critical size determined by the effective radius of the repulsive grains.Comment: 6 pages, 8 figure

Multivector Field Formulation of Hamiltonian Field Theories: Equations and Symmetries

We state the intrinsic form of the Hamiltonian equations of first-order Classical Field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study several aspects of these equations, such as the existence and non-uniqueness of solutions, and the integrability problem. In particular, these problems are analyzed for the case of Hamiltonian systems defined in a submanifold of the multimomentum bundle. Furthermore, the existence of first integrals of these Hamiltonian equations is considered, and the relation between {\sl Cartan-Noether symmetries} and {\sl general symmetries} of the system is discussed. Noether's theorem is also stated in this context, both the ``classical'' version and its generalization to include higher-order Cartan-Noether symmetries. Finally, the equivalence between the Lagrangian and Hamiltonian formalisms is also discussed.Comment: Some minor mistakes are corrected. Bibliography is updated. To be published in J. Phys. A: Mathematical and Genera

On the k-Symplectic, k-Cosymplectic and Multisymplectic Formalisms of Classical Field Theories

The objective of this work is twofold: First, we analyze the relation between the k-cosymplectic and the k-symplectic Hamiltonian and Lagrangian formalisms in classical field theories. In particular, we prove the equivalence between k-symplectic field theories and the so-called autonomous k-cosymplectic field theories, extending in this way the description of the symplectic formalism of autonomous systems as a particular case of the cosymplectic formalism in non-autonomous mechanics. Furthermore, we clarify some aspects of the geometric character of the solutions to the Hamilton-de Donder-Weyl and the Euler-Lagrange equations in these formalisms. Second, we study the equivalence between k-cosymplectic and a particular kind of multisymplectic Hamiltonian and Lagrangian field theories (those where the configuration bundle of the theory is trivial).Comment: 25 page

Invariant Forms and Automorphisms of Locally Homogeneous Multisymplectic Manifolds

It is shown that the geometry of locally homogeneous multisymplectic manifolds (that is, smooth manifolds equipped with a closed nondegenerate form of degree > 1, which is locally homogeneous of degree k with respect to a local Euler field) is characterized by their automorphisms. Thus, locally homogeneous multisymplectic manifolds extend the family of classical geometries possessing a similar property: symplectic, volume and contact. The proof of the first result relies on the characterization of invariant differential forms with respect to the graded Lie algebra of infinitesimal automorphisms, and on the study of the local properties of Hamiltonian vector fields on locally multisymplectic manifolds. In particular it is proved that the group of multisymplectic diffeomorphisms acts (strongly locally) transitively on the manifold. It is also shown that the graded Lie algebra of infinitesimal automorphisms of a locally homogeneous multisymplectic manifold characterizes their multisymplectic diffeomorphisms.Comment: 25 p.; LaTeX file. The paper has been partially rewritten. Some terminology has been changed. The proof of some theorems and lemmas have been revised. The title and the abstract are slightly modified. An appendix is added. The bibliography is update

Properties of Multisymplectic Manifolds

This lecture is devoted to review some of the main properties of multisymplectic geometry. In particular, after reminding the standard definition of multisymplectic manifold, we introduce its characteristic submanifolds, the canonical models, and other relevant kinds of multisymplectic manifolds, such as those where the existence of Darboux-type coordinates is assured. The Hamiltonian structures that can be defined in these manifolds are also studied, as well as other important properties, such as their invariant forms and the characterization by automorphisms.Comment: 10 pp. Changes in Sections 5 and 7 (where brief guides to the proofs of theorems have been added). Lecture given at the workshop on {\sl Classical and Quantum Physics: Geometry, Dynamics and Control. (60 Years Alberto Ibort Fest), Instituto de Ciencias Matem\'aticas (ICMAT)}, Madrid (Spain), 5--9 March 201

Entity reconciliation in big data sources: A systematic mapping study

The entity reconciliation (ER) problem aroused much interest as a research topic in today’s Big Dataera, full of big and open heterogeneous data sources. This problem poses when relevant information ona topic needs to be obtained using methods based on: (i) identifying records that represent the samereal world entity, and (ii) identifying those records that are similar but do not correspond to the samereal-world entity. ER is an operational intelligence process, whereby organizations can unify differentand heterogeneous data sources in order to relate possible matches of non-obvious entities. Besides, thecomplexity that the heterogeneity of data sources involves, the large number of records and differencesamong languages, for instance, must be added. This paper describes a Systematic Mapping Study (SMS) ofjournal articles, conferences and workshops published from 2010 to 2017 to solve the problem describedbefore, first trying to understand the state-of-the-art, and then identifying any gaps in current research.Eleven digital libraries were analyzed following a systematic, semiautomatic and rigorous process thathas resulted in 61 primary studies. They represent a great variety of intelligent proposals that aim tosolve ER. The conclusion obtained is that most of the research is based on the operational phase asopposed to the design phase, and most studies have been tested on real-world data sources, where a lotof them are heterogeneous, but just a few apply to industry. There is a clear trend in research techniquesbased on clustering/blocking and graphs, although the level of automation of the proposals is hardly evermentioned in the research work.Ministerio de Economía y Competitividad TIN2013-46928-C3-3-RMinisterio de Economía y Competitividad TIN2016-76956-C3-2-RMinisterio de Economía y Competitividad TIN2015-71938-RED

FUsaM: Framework for Measuring Usability Mobile Applications Based on an SPL

El uso masivo de los dispositivos móviles, asociado a la heterogeneidad de estos y también de los usuarios, implica un desafío al momento de evaluar la usabilidad de las aplicaciones móviles. Es importante disponer de metodologías y herramientas que permitan realizar estudios de usabilidad específicos para este tipo de aplicaciones en las cuales el contexto de uso cambia continuamente. Es necesario que las pruebas de usabilidad sean transparentes para el usuario, recolecten datos de usabilidad  y del contexto de manera automática, no sean intrusivas para la aplicación que se prueba y que soporten en alguna medida la variabilidad de los dispositivos. Para lograr las características mencionadas, en este trabajo se propone un framework denominado FUsaM (Framework de usabilidad móvil) que es extensible y permite generar e integrar pruebas de usabilidad en aplicaciones móviles. Para su diseño e implementación se utiliza el enfoque de construcción de Línea de productos de software (SPL, Software Product Line) combinado con la Programación orientada a características (FOP, Feature-Oriented Programming) y la Programación orientada a aspectos (AOP, Aspect-Oriented Programming). También se presenta un caso de estudio para demostrar la funcionalidad de este.The widespread use of mobile devices and the heterogeneity of the users involves challenges when evaluating usability of mobile applications. It is important to have methodologies and tools that enable to perform specific usability studies for this type of applications in which the context of use is constantly changing. It is necessary that usability testing are transparent to the user, usability and context data are automatically collected, the test code are not intrusive in the tested application and the tests support the variability of the devices. To achieve the above features, this article presents a framework called FUsaM (Mobile Usability Framework) which is extensible and can generate and integrate usability testing in mobile applications. The design and implementation approach is based on Software Product Line (SPL) combined with Features Oriented Programming (FOP) and Aspect Oriented Programming (AOP). A case study is also presented to prove the functionality.&nbsp

Challenges for the adoption of model-driven web engineering approaches in industry

Model-Driven Web Engineering approaches have become an attractive research and technology solution for Web application development. However, for more than 20 years of development, the industry has not adopted them due to the mismatch between technical versus research requirements. In the context of this joint work between academia and industry, the authors conduct a survey among hundreds of engineers from different companies around the world and, by statistical analysis, they present the current problems of these approaches in scale. Then, a set of guidelines is provided to improve Model-Driven Web Engineering approaches in order to make them viable industry solutions.Facultad de InformáticaLaboratorio de Investigación y Formación en Informática Avanzad

Classical field theory on Lie algebroids: Variational aspects

The variational formalism for classical field theories is extended to the setting of Lie algebroids. Given a Lagrangian function we study the problem of finding critical points of the action functional when we restrict the fields to be morphisms of Lie algebroids. In addition to the standard case, our formalism includes as particular examples the case of systems with symmetry (covariant Euler-Poincare and Lagrange Poincare cases), Sigma models or Chern-Simons theories.Comment: Talk deliverd at the 9th International Conference on Differential Geometry and its Applications, Prague, September 2004. References adde

Competencias necesarias en el ejercicio de la profesión de ingeniería informática: Experimento sobre la percepción de los estudiantes

Congreso Universitario de Innovación Educativa En las Enseñanzas Técnicas, CUIEET (26º. 2018. Gijón