Revisión de algoritmos para modelización de equilibrios de distribución de metales en procesos de extracción líquido-líquido

10 pages, 5 figures, 2 tables, 1 appendix.[EN] This work focuses on general guidelines to be considered for application of least-squares routines and artificial neural networks (ANN) in the estimation of metal distribution equilibria in liquid-liquid extraction process. The goal of the procedure in the statistical method is to find the values of the equilibrium constants (K¡) for the reactions involved in the metal extraction which minimizes the differences between experimental distribution coefficient (Dgxp) and theoretical distribution coefficients according to the mechanism proposed (Dt^^gor)- Iri the first part of the article, results obtained with the most frequently routine reported in the bibliography are compared with those obtained using the algorithms previously discussed. In the second part, the main features of a single back-propagation neural network for the same purpose are discussed, and the results obtained are compared with those obtained with the classical methods.[ES] El trabajo presenta las líneas generales a considerar para la estimación del equilibrio de distribución de metales en procesos de extracción líquido-líquido, según dos métodos: algoritmo clásico de mínimos cuadrados y redes neuronales artificiales. El objetivo del procedimiento, en el caso del método estadístico, es encontrar los valores de las constantes de equilibrio (KJ para las reacciones involucradas en la extracción del metal, que minimizan las diferencias entre el coeficiente de distribución experimental y el coeficiente de distribución teórico, de acuerdo al mecanismo propuesto. En la primera parte del artículo se comparan los resultados obtenidos a partir de los algoritmos usados más habitualmente en la bibliografía, con los datos obtenidos mediante el algoritmo previamente descrito. En la segunda parte, se presentan las características fundamentales para aplicar una red neuronal sencilla con algoritmo hack-propagatioriy y los resultados obtenidos se comparan con los de los métodos clásicos.Peer reviewe

Fiber sensors for the high-speed railway environment

Specialty Optical Fibers 2014, Barcelona, Spain, 27–31 July 2014We review some recent work on fiber-optic sensors for the high-speed railway environment. In particular, we show convenient fiber-optic solutions for rail and wheel monitoring, perimeter security and catenary protection in changeover section

Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

A Spanish hazardous waste from tertiary aluminium industry was used as a raw material for the synthesis of calcium aluminate. An amorphous precursor was obtained by a hydrothermal method at different values of pH. The transformation of the precursor in a crystalline aluminate was followed by TG/DTA up to 1300 C. At temperatures between 719 and 744 C, the precursors evolve towards the formation of C12A7 which becomes CA at circa 1016 C. Mass spectrometry coupled to thermal analyser allowed the identification of the decomposition productsMEC for financing project CTM2005-01964 and the company Recuperaciones y Reciclajes Roman S.L. (Fuenlabrada, Madrid, Spain) for supplying the waste and Dr. M. I. Martı´n for the FRX analysis and Dr. I. Padilla for the technical assistance. Laura Delgado-Gonzalo is grateful to the CSIC (Spanish National Research Council) for an I3P contractPeer reviewe

The use of seismic arrays to study the seismo-volcanic source. The example of Mt Etna and Stromboli Volcano.

The properties of volcanic tremor wavefields at Mt Etna Volcano, Italy, are investigated using data from two dense, small aperture arrays of short-period seismometers deployed on the North and South flank of the volcano. Spectral analysis shows that most of the seismic energy is associated with several, narrow spectral peaks spanning the 1–5 Hz frequency band. Analysis of simultaneous recordings indicates that most of these peaks are common to different sites, thus suggesting a source effect as the origin of this energy. Frequency-slowness analyses show a complex wavefield, where body- and surface-waves alternatively dominate depending on the frequency band and the component of motion taken into account. Using a probabilistic approach, we invert slowness data measured at two dense arrays for retrieving source location and extent. The joint inversion of slowness data from the two arrays points to different source locations. This observation is interpreted in terms of ray bending associated with lateral heterogeneity and/or strong topographic effects on wave propagation. Once the propagation effects are taken into account, the most probable source location is a shallow region encompassing the summit craters and the eruptive fissures active at the time of the experiment. Data from two dense arrays of short-period seismometers are used to retrieve source locations of the explosion quakes at Stromboli volcano. Slowness vectors estimated at both arrays with the zero-lag cross-correlation technique constitute the experimental data set. A probabilistic approach based on a grid search spanning the volcano interior is used to calculate the probability of the source location. Results show a shallow source, located beneath the crater area, at depths not greater than 500 m below the surface

Obtained and characterization of composite materials W-Cu for electrical contact

9 páginas, 5 figuras, 4 tablas.-- Nota técnica.[ES] En el Centro de Investigaciones Metalúrgicas (CIME), cubano, se fabrican por pulvimetalurgia, calzos de material compuesto volframio-cobre, que se utilizan en los contactos eléctricos de los paneles de control de las grúas pórtico que operan en el puerto de Ciudad de La Habana. El material base que se utiliza contiene un 70 % en masa de polvo de cobre electrolítico y polvo de volframio (30 %), que se obtiene por reducción del óxido de volframio. Los polvos se someten a las etapas de mezclado, prensado y sinterización obteniéndose un material compuesto con las fases metálicas formadas por partículas libres de volframio ocluidas en una matriz de cobre, que no interaccionan entre sí. Este material compuesto proporciona al calzo de ajuste las siguientes propiedades: alta temperatura de fusión, alta electrotermoconductividad y resistencia a la corrosión, alta resistencia mecánica y a la erosión eléctrica, baja soldabilidad y estabilidad durante su explotación. Sin embargo, al no reaccionar las partículas de volframio con el cobre, el material compuesto comenzará a fundir a la temperatura del cobre; por otro lado y, por la misma razón la resistencia a la corrosión debe ser similar a la del cobre puro. Los calzos de ajuste se fijan a los cuerpos de cobre de alta pureza mediante una soldadura de una aleación de plata, la cual no afecta las buenas cualidades del cobre, como elasticidad, resistencia a la tracción, conductividad térmica y eléctrica, así como resistencia a la corrosión.[EN] In the Cuban Metallurgical Research Center (CIME), are manufactured by powder metallurgy, shims of adjustment of a W-Cu composite material, that are used in the electrical contacts of the panels of control of the portico derricks that operate in the port of Havana City. The base material used has a composition of 70 % in mass electrolytic copper powder and wolfram powder of (30 %) that is obtained by reduction from the oxide from wolfram. The powders are submitted to the stages of mixed, pressed and agglomeration and is obtained a composite material with free particles of W occluded in a counterfoil of Cu matrix, that do not interact and they provide the following properties: high melting temperature, high electro and thermo conductivity and corrosion resistance, high mechanical and electrical strengtheners, decrease weldability and stability during their development. However, when not reacting the volframio particles with the copper, the compound material will begin to fuse to the temperature of the copper, on the other hand and for the same reason the resistance to the corrosion should be similar to that of the pure copper. The shims of adjustment are fixed to the bodies of high purity copper welding with a silver alloy, the one which provides the maximum qualities of the Cu, as elasticity, breaking strength, thermal and electrical conductivities, as well corrosion resistance.Peer reviewe

Detecting intention to walk in stroke patients from pre-movement EEG correlates

Background: Most studies in the field of brain-computer interfacing (BCI) for lower limbs rehabilitation are carried out with healthy subjects, even though insights gained from healthy populations may not generalize to patients in need of a BCI. Methods: We investigate the ability of a BCI to detect the intention to walk in stroke patients from pre-movement EEG correlates. Moreover, we also investigated how the motivation of the patients to execute a task related to the rehabilitation therapy affects the BCI accuracy. Nine chronic stroke patients performed a self-initiated walking task during three sessions, with an intersession interval of one week. Results: Using a decoder that combines temporal and spectral sparse classifiers we detected pre-movement state with an accuracy of 64 % in a range between 18 % and 85.2 %, with the chance level at 4 %. Furthermore, we found a significantly strong positive correlation (r = 0.561, p = 0.048) between the motivation of the patients to perform the rehabilitation related task and the accuracy of the BCI detector of their intention to walk. Conclusions: We show that a detector based on temporal and spectral features can be used to classify pre-movement state in stroke patients. Additionally, we found that patients'' motivation to perform the task showed a strong correlation to the attained detection rate of their walking intention

Effect of surfactants on the deformation and break-up of an aqueous drop in oils under high electric field strengths

Understanding the deformation and break-up of drops is of great significance in various applications such as emulsification and phase separation. Most practical systems contain surface-active agents that are present as impurities affecting the properties of the system, e.g. modifying the rigidity of the film that affects emulsion stability. In this paper, the effect of surfactants on the deformation and break-up of an aqueous drop in an immiscible dielectric oil under the action of an electric field is addressed. The experiments were carried out on a single drop in a microscopic cell under an applied external electric field. A nonionic surfactant, polyethylene glycol sorbitan monolaurate (Tween 20), and an ionic surfactant, sodium dodecyl sulfate (SDS), were used at different concentrations. The drop adopted in most cases a prolate shape. However, the presence of the surfactant affected both the extent of deformation and the modes of break-up. The drop deformation extent increased rapidly with the surfactant concentration, while smaller drops deformed less under the same external electric field strength. When the surfactant concentration was high, the position of break-up could be from both poles along the main axis of the drops in the direction of the electric field

Twin digital short period seismic Array Experiment at Stromboli Volcano

Two small arrays composed by short period (1 Hz) digital seismic stations, with an aperture of approximately 400 meters, were set up at Stromboli volcano (one at semaforo Labronzo, the other at Ginostra- Timpone del Fuoco) with the purpose of the spatial location of the high frequency source of the explosion quakes. About 75 explosion-quakes were recorded at both arrays, and constitute the available data base. We have planned to apply the zero-lag cross-correlation technique to the whole data set in order to obtain back-azimuth and apparent slowness of the coherent seismic phases. A preliminary analysis for both arrays show that the predominant back-azimuth for the first phase is oriented in the direction of , but not strictly coincident to, the crater area. Moreover some back-scattered arrivals are quite evident in the seismogram.INGV - Osservatorio VesuvianoUnpublishedope

Low Latency Estimation of Motor Intentions to Assist Reaching Movements along Multiple Sessions in Chronic Stroke Patients: A Feasibility Study

A corrigendum on Low Latency Estimation of Motor Intentions to Assist Reaching Movements along Multiple Sessions in Chronic Stroke Patients: A Feasibility Study by Ibáñez, J., Monge-Pereira, E., Molina-Rueda, F., Serrano, J. I., del Castillo, M. D., Cuesta-Gómez, A., et al. (2017). Front. Neurosci. 11:126. doi: 10.3389/fnins.2017.00126. In the recently published article, there were incorrect and missing contents in the Acknowledgments section