Discrete Nonholonomic Lagrangian Systems on Lie Groupoids

This paper studies the construction of geometric integrators for nonholonomic systems. We derive the nonholonomic discrete Euler-Lagrange equations in a setting which permits to deduce geometric integrators for continuous nonholonomic systems (reduced or not). The formalism is given in terms of Lie groupoids, specifying a discrete Lagrangian and a constraint submanifold on it. Additionally, it is necessary to fix a vector subbundle of the Lie algebroid associated to the Lie groupoid. We also discuss the existence of nonholonomic evolution operators in terms of the discrete nonholonomic Legendre transformations and in terms of adequate decompositions of the prolongation of the Lie groupoid. The characterization of the reversibility of the evolution operator and the discrete nonholonomic momentum equation are also considered. Finally, we illustrate with several classical examples the wide range of application of the theory (the discrete nonholonomic constrained particle, the Suslov system, the Chaplygin sleigh, the Veselova system, the rolling ball on a rotating table and the two wheeled planar mobile robot).Comment: 45 page

Discrete Variational Optimal Control

This paper develops numerical methods for optimal control of mechanical systems in the Lagrangian setting. It extends the theory of discrete mechanics to enable the solutions of optimal control problems through the discretization of variational principles. The key point is to solve the optimal control problem as a variational integrator of a specially constructed higher-dimensional system. The developed framework applies to systems on tangent bundles, Lie groups, underactuated and nonholonomic systems with symmetries, and can approximate either smooth or discontinuous control inputs. The resulting methods inherit the preservation properties of variational integrators and result in numerically robust and easily implementable algorithms. Several theoretical and a practical examples, e.g. the control of an underwater vehicle, will illustrate the application of the proposed approach.Comment: 30 pages, 6 figure

Primeros datos polínicos de la secuencia "fuentillejo-1" de la laguna del Maar de Fuentillejo (Campo de Calatrava, Ciudad Real)

XV lnternational A.P.L.E. Symposium of Palynolog

Development and Initial testing of a Virtual Laboratory for the Build-up and Testing of Microgrid Management Algorithms

In a bid of facilitating the increasing penetration of intermittent and random renewable energies, microgrids along with their management algorithms are becoming crucial assets. To prove their effectiveness, these algorithms need to be tested in real environments and/or laboratories, which can be very difficult in many cases, especially at the initial development stages. To solve this issue, this article proposes the use of a laboratory digital twin, i.e., a virtual laboratory with a behaviour that is similar to that of real installations, aimed at facilitating the development, testing and debugging of microgrids management algorithms. The proposed solution is demonstrated to be safe and complete when it comes to test these algorithms.Acknowledgement This publication is part of the Sistemas energéticos aislados 100% renovables ENERISLA (exp. CER-20191002) Project which has received a grant from the Centre for Industrial Technological Development (CDTI, Centro para el Desarrollo Tecnológico Industrial in Spanish) under the Ministry of Science and Innovation in the call Acreditación y Concesión de Ayudas destinadas a Centros Tecnológicos de Excelencia “Cervera” in 2019. This research has received funding from the European Union’s Horizon 2020 Framework Program for Research and Innovation under grant agreement no. 893857

Flux-cutting and flux-transport effects in type-II superconductor slabs in a parallel rotating magnetic field

The magnetic response of irreversible type-II superconductor slabs subjected to in-plane rotating magnetic field is investigated by applying the circular, elliptic, extended-elliptic, and rectangular flux-line-cutting criticalstate models. Specifically, the models have been applied to explain experiments on a PbBi rotating disk in a fixed magnetic field Ha, parallel to the flat surfaces. Here, we have exploited the equivalency of the experimental situation with that of a fixed disk under the action of a parallel magnetic field, rotating in the opposite sense. The effect of both the magnitude Ha of the applied magnetic field and its angle of rotation αs upon the magnetization of the superconductor sample is analyzed. When Ha is smaller than the penetration field HP, the magnetization components, parallel and perpendicular to Ha, oscillate with increasing the rotation angle. On the other hand, if the magnitude of the applied field, Ha, is larger than HP, both magnetization components become constant functions of α s at large rotation angles. The evolution of the magnetic induction profiles inside the superconductor is also studied

First release of the IPHAS catalogue of new extended planetary nebulae

Date of Acceptance: 30/06/2014We present the first results of our search for new, extended planetary nebulae (PNe) based on careful, systematic, visual scrutiny of the imaging data from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane (IPHAS). The newly uncovered PNe will help to improve the census of this important population of Galactic objects that serve as key windows into the late-stage evolution of low- to intermediate-mass stars. They will also facilitate study of the faint end of the ensemble Galactic PN luminosity function. The sensitivity and coverage of IPHAS allows PNe to be found in regions of greater extinction in the Galactic plane and/or those PNe in a more advanced evolutionary state and at larger distances compared to the general Galactic PN population. Using a set of newly revised optical diagnostic diagrams in combination with access to a powerful, new, multiwavelength imaging data base, we have identified 159 true, likely and possible PNe for this first catalogue release. The ability of IPHAS to unveil PNe at low Galactic latitudes and towards the Galactic Anticentre, compared to previous surveys, makes this survey an ideal tool to contribute to the improvement of our knowledge of the whole Galactic PN population.Peer reviewe

Variational and Geometric Structures of Discrete Dirac Mechanics

In this paper, we develop the theoretical foundations of discrete Dirac mechanics, that is, discrete mechanics of degenerate Lagrangian/Hamiltonian systems with constraints. We first construct discrete analogues of Tulczyjew's triple and induced Dirac structures by considering the geometry of symplectic maps and their associated generating functions. We demonstrate that this framework provides a means of deriving discrete Lagrange-Dirac and nonholonomic Hamiltonian systems. In particular, this yields nonholonomic Lagrangian and Hamiltonian integrators. We also introduce discrete Lagrange-d'Alembert-Pontryagin and Hamilton-d'Alembert variational principles, which provide an alternative derivation of the same set of integration algorithms. The paper provides a unified treatment of discrete Lagrangian and Hamiltonian mechanics in the more general setting of discrete Dirac mechanics, as well as a generalization of symplectic and Poisson integrators to the broader category of Dirac integrators.Comment: 26 pages; published online in Foundations of Computational Mathematics (2011

Aplicaciones de metodologías moleculares y biotecnológicas en la investigación sobre las enfermedades de cultivos en la Agricultura Sostenible

Las enfermedades son un componente de significación en la producción agrícola actual porque pueden reducir el rendimiento potencial o causar devastación en los cultivos de plantas; y la extensión y severidad de sus ataques va unida a los cambios que se están produciendo en los sistemas de manejo que dan lugar a mejoras en el rendimiento o modificaciones en los ambientes de producción. El control eficiente de las enfermedades requiere necesariamente la determinación exacta, rápida e informativa de su etiología, incluyendo la evaluación de la historia y potencial evolutivo en las poblaciones del agente causal, así como de la composición y diversidad de la microbiota beneficiosa asociada con el crecimiento vegetal, que hagan posible la aplicación eficiente de las acciones de prevención en que se fundamenta el manejo sostenible de dichas enfermedades. Las tecnologías de base molecular y biotecnológica ofrecen una excelente oportunidad para mejorar nuestras capacidades para satisfacer dichos requisitos. En este trabajo se ilustran tales oportunidades utilizando como ejemplo los resultados alcanzados por el Grupo AGR136 ‘Sanidad Vegetal’ durante el desarrollo de programa de investigación llevados a cabo sobre enfermedades importantes en la agricultura andaluz

La Cueva de El Sidrón (Piloña Asturias)

Estado de las excavaciones y estudios en la Cueva de El Sidrón (PIloña, Asturias)