A decomposition procedure based on approximate newton directions

The efficient solution of large-scale linear and nonlinear optimization problems may require exploiting any special structure in them in an efficient manner. We describe and analyze some cases in which this special structure can be used with very little cost to obtain search directions from decomposed subproblems. We also study how to correct these directions using (decomposable) preconditioned conjugate gradient methods to ensure local convergence in all cases. The choice of appropriate preconditioners results in a natural manner from the structure in the problem. Finally, we conduct computational experiments to compare the resulting procedures with direct methods, as well as to study the impact of different preconditioner choices

Speaker recognition using frequency filtered spectral energies

The spectral parameters that result from filtering the frequency sequence of log mel-scaled filter-bank energies with a simple first or second order FIR filter have proved to be an efficient speech representation in terms of both speech recognition rate and computational load. Recently, the authors have shown that this frequency filtering can approximately equalize the cepstrum variance enhancing the oscillations of the spectral envelope curve that are most effective for discrimination between speakers. Even better speaker identification results than using melcepstrum have been obtained on the TIMIT database, especially when white noise was added. On the other hand, the hybridization of both linear prediction and filter-bank spectral analysis using either cepstral transformation or the alternative frequency filtering has been explored for speaker verification. The combination of hybrid spectral analysis and frequency filtering, that had shown to be able to outperform the conventional techniques in clean and noisy word recognition, has yield good text-dependent speaker verification results on the new speaker-oriented telephone-line POLYCOST database.Peer ReviewedPostprint (published version

Egyptian blue and/or atacamite in an ancient egyptian coffin

This work deals with the composition of the blue and green pigments used in the wooden sarcophagus studied by Abdelaal et al. and published in 2014 in this journal. From the published data, a degradation of the originally used Egyptian blue pigment is proposed. The presence of chlorine in the pigment deduced from SEM-EDS analyses and the greenish hue observed point to the formation of a certain amount of atacamite (or one of its polymorphs, paratacamite or clionoatacamite) because of the Egyptian blue degradation process named copper chloride cancer.Postprint (author's final draft

Dora maar & margaret michaelis: two photographers in front of the art and architecture

El interés por la labor callada del artista en su estudio o la atención continuada a la lenta gestación de la arquitectura, han sido constantes desde hace tiempo. Los buenos fotógrafos han estado siempre dispuestos a poner su mirada atenta sobre estos procesos. Resulta sumamente interesante desgranar lo ocurrido en este campo en las primeras décadas del siglo xx, y muy especialmente en los años que precedieron a la guerra civil española. De aquellos años, me fijaré en las figuras de dos mujeres fotógrafas –Dora Maar y Margaret Michaelis–, que entendieron el seguimiento de los procesos creativos como parte fundamental de su creación artistica y, gracias a las cuales, descubriremos a sus autores, visualizaremos los escenarios de su gestación y disfrutaremos con la plástica de sus procesos constructivos.The interest of the silent work of the artist in his studio or the continued attention of the slow gestation of the architecture, have been constant since long time ago. The good photographers have always been ready to put their careful look on this processes. It’s very interesting to peel what ocurred in the first decades of the 20Th century, and specially on the years before the spanish civil war. In this years, I will observe the figures of two women photographers – Dora Maar and Margaret Michaelis– that understood the creative processes as a fundamental part of the artistic creation, and thanks to which, we discovered this authors, we visualize the scenes of their gestation and we enjoy with the plastic arts of their constructive advances