BV analysis for covariant and non-covariant actions

The equivalence between the covariant and the non-covariant version of a constrained system is shown to hold after quantization in the framework of the field-antifield formalism. Our study covers the cases of Electromagnetism and Yang-Mills fields and sheds light on some aspects of the Faddeev-Popov method, for both the coratiant and non-covariant approaches, which had not been fully clarified in the literature.Comment: 21 pages, preprint # UTTG-02-93, UB-ECM-PF 93/5. To appear in Phys. Rev.

Symmetric Variational Formulation of BIE for Domain Decomposition Problems in Elasticity – An SGBEM Approach for Nonconforming Discretizations of Curved Interfaces

An original approach to solve domain decomposition problems by the symmetric Galerkin boundary element method is developed. The approach, based on a new variational principle for such problems, yields a fully symmetric system of equations. A natural property of the proposed approach is its capability to deal with nonconforming discretizations along straight and curved interfaces, allowing in this way an independent meshing of non-overlapping subdomains to be performed. Weak coupling conditions of equilibrium and compatibility at an interface are obtained from the critical point conditions of the energy functional. Equilibrium is imposed through local traction (Neumann) boundary conditions prescribed on a subdomain situated at one side of the interface, and compatibility is imposed through local displacement (Dirichlet) boundary conditions prescribed on the other subdomain situated at the opposite side of the interface. No additional unknowns such as Lagrange multipliers are introduced. An SGBEM code for 2D elastic domain decomposition problems has been implemented. The effectiveness of the approach developed is documented by numerical examples involving non-matching linear boundary element meshes at the interfaces, where the accuracy is analyzed by comparing the numerical results obtained versus the analytical solutions and by evaluating the convergence rate of the error in the (discretized) integral L2-norm and maximum-normfor h-refinements of boundary element meshes. Finally, a theoretical analysis of a problem with an interior and an exterior subdomain is introduced to explain the observed behaviour of numerical results

Campo tensional en el entorno de una fisura. Determinación de KI y KII usando técnicas fotoelásticas

Trabajo reproducido y difundido en el repositorio idUS con permiso de la Asociación Española de Ingeniería Mecánica (AEIM)Tras introducir la forma general del campo de tensiones en un borde de grieta se hace una exposición detallada de los métodos para medir K I y K II, resaltando sus ventajas e inconvenientes. Por su generalldad, se ha implementado un método que desarrolla en serie las funciones de tensión. La introducción de las medidas fotoelásticas (que pueden ser de campo lejano) conduce a un sistema sobredetermlnado no lineal de ecuaclones, que es resuelto por un métooo de Neewton-Raphson y mínimos cuadrados. Sobre una aplicación experimental se comentan las caracterlstlcas de este métodoFirst of all, the general form of the crack-tip stress field is introduced. Then, a detailed review of K I-K II methods is pressented, showing thelr features. A stress-functions series expansion method has been implemented, due to its generality. Experimental far-fleld isochromatic polnts are used to fit the series expanslon coefflclents and the overdeterminlstlc non-linear equation system is solved with a Newton-Rapshon least-squares method. Finally the features of thls method are dlscussed uslng an experimental applicatio

Comparación de la gestión del riego automatizado con tensiómetros frente a la estimación de la evapotranspiración en cultivos hortícolas bajo invernadero

La sostenibilidad del uso del agua en la agricultura se ha convertido en una prioridad y la adopción de estrategias de riego que permitan un uso eficiente de la misma manteniendo niveles de producción satisfactorios, en una necesidad. En particular, en áreas que presentan escasez de recursos hídricos, como la Mediterránea, resulta imprescindible maximizar la eficiencia en el uso del agua y la productividad de la misma. En este trabajo se compara la gestión del riego automatizado empleando tensiómetros electrónicos con la estimación de las necesidades hídricas en un cultivo de calabacín en invernadero. La comparación entre los consumos de agua de los tres tratamientos de riego ensayados y la ETc estimada a partir de datos reales de clima (ETc-r) muestra que el tratamiento T2 con una consigna de potencial matricial de -25 kPa y una dotación de 2 L m tuvo un consumo igual al calculado mediante la ETc-r (315 Lm ). Este tratamiento junto con el T3 (-40 kPa y 3 L m presentaron los mejores resultados en cuanto a eficiencia en el uso del agua. Sin embargo, el T3 redujo significativamente la cosecha en un 16%. Por tanto, la activación automática del riego con la consigna del T2 fue la que mejores resultados arrojó aunando eficiencia y productividad

Particle creation in an oscillating spherical cavity

We study the creation of massless scalar particles from the quantum vacuum due to the dynamical Casimir effect by spherical shell with oscillating radius. In the case of a small amplitude of the oscillation, to solve the infinite set of coupled differential equations for the instantaneous basis expansion coefficients we use the method based on the time-dependent perturbation theory of the quantum mechanics. To the first order of the amplitude we derive the expressions for the number of the created particles for both parametric resonance and non-resonance cases.Comment: 8 pages, LaTeX, no figure

Estudio experimental de placas preconformadas en postpandeo

XI CONGRESO NACIONAL DE MATERIALES COMPUESTOS. Celebrado en Móstoles los días 6, 7 y 8 de julio de 2015El pandeo de placas y láminas no necesariamente está asociado al colapso, que en ocasiones se produce para una carga que es varias veces superior. No obstante, aprovechar esta capacidad postpandeo no es fácil, siendo el principal inconveniente la extremada sensibilidad del problema ante imperfecciones de la geometría y las condiciones de sustentación y de cargas. En este trabajo se muestran los primeros resultados de un análisis de la evolución en postpandeo de placas de material compuesto en las que, intencionadamente, se han introducido imperfecciones iniciales.Junta de Andalucía TEP-7093Ministerio de Economía y Competitividad DPI2012-3718

Modelling ultrasonic debulking of tape lamination

COMATCOMP 09 : Donostia - San Sebastian, 7, 8 y 9 de octubre de 2009A numerical model is presented, which has been developed to study the quality of the ultrasonic debulking of a composite laminate. The quality of the debulking level will depend, primarily, of the temperature raised in the laminate. For that reason, the evolution in time of the temperature inside the composite laminate has been studied. To this end, a thermal model has been developed which leads to the determination of the temperature inside the laminate from the values of the temperature at the tip of the ultrasonic horn. To validate the model, the numerical results have been compared with experimental measurements in a particular case

The Inflationary Perturbation Spectrum

Motivated by the prospect of testing inflation from precision cosmic microwave background observations, we present analytic results for scalar and tensor perturbations in single-field inflation models based on the application of uniform approximations. This technique is systematically improvable, possesses controlled error bounds, and does not rely on assuming the slow-roll parameters to be constant. We provide closed-form expressions for the power spectra and the corresponding scalar and tensor spectral indices.Comment: 4 pages, 1 figur