Estudio de las variables que afectan la rugosidad superficial en el torneado de piezas esbeltas bajo retemblado

El mecanizado de piezas delgadas se encuentra influenciado por un fenómeno denominado retemblado, que afecta la calidad superficial. En este trabajo se presenta un estudio de los factores que influyen sobre la rugosidad superficial en un proceso de torneado de cilindros esbeltos bajo el efecto del fenómeno de retemblado. El propósito del estudio es determinar cuales son las variables del proceso que más influyen sobre la rugosidad superficial. Para ello se utiliza un modelo que permite predecir la topografía superficial en operaciones de torneado con retemblado. El modelo se encuentra en función de los parámetros de corte y las propiedades del material a mecanizar

Application of mixture design with the PHVA cycle for the optimization of the properties of an architectural coating

Este trabajo aplicó el diseño de mezclas con el ciclo PHVA para la optimización de las propiedades de un recubrimiento arquitectónico. En la etapa Planificar se diseñó un plan experimental que permita alcanzar las propiedades de interés, se estableció como componentes principales de la mezcla a tres tipos de cargas; carbonato de calcio, talco y caolín. El diseño simplex con centroide aumentado se utilizó para ejecutar las corridas experimentales (Hacer), se ejecutaron 20 experimentos en total y fueron caracterizados en cuanto a viscosidad, porcentaje de relación de contraste, porcentaje blancura, brillo y costo. En la etapa Verificar, se evaluaron los resultados experimentales y cada propiedad se ajustó a un modelo estadístico para la predicción de sus valores. La viscosidad, porcentaje de blancura y brillo fueron ajustados a un modelo cuadrático y el porcentaje de relación de contraste fue ajustado a un modelo cúbico especial. Finalmente, en la etapa Actuar, se realizó la optimización de las propiedades de acuerdo con las restricciones establecidas y al menor costo posible. La mezcla óptima estuvo compuesta por 0,2934 de carbonato de calcio, 0,5450 de talco y 0,1616 de caolín. La prueba experimental se realizó con la mezcla optimizada para garantizar la exactitud y precisión de los resultados del modelo estadístico.This work applied the mixture design with the PDCA cycle for the optimization of the properties of an architectural coating. In the Plan stage, an experimental plan was designed to achieve the properties of interest; three types of fillers; calcium carbonate, talc and kaolin were established as the main components of the mixture. The simplex design with increased centroid was used to execute the experimental runs (Do), 20 experiments were executed in total and were characterized in terms of viscosity, contrast ratio percentage, whiteness percentage, brightness and cost. In the Check stage, the experimental results were evaluated and each property was fitted to a statistical model for the prediction of its values. The viscosity, percent whiteness and gloss were fitted to a quadratic model and the percent contrast ratio was fitted to a special cubic model. Finally, in the Act stage, the properties were optimized according to the established restrictions and at the lowest possible cost. The optimum mixture was composed of 0.2934 calcium carbonate, 0.5450 talc and 0.1616 kaolin. The experimental test was carried out with the optimized mixture to guarantee the accuracy and precision of the results of the statistical model

Modelos para la predicción de la rugosidad superficial en procesos de mecanizado con arranque de viruta: revisión bibliográfica

El tema de la Rugosidad Superficial ha sido ampliamente estudiado por muchos autores, en busca de intentar predecir su comportamiento, así como definir los diferentes factores que la determinan. El presente artículo presenta una revisión de los diferentes enfoques usados para su predicción

Morphological studies of the Spitzer Wide-Area Infrared Extragalactic survey galaxy population in the UGC 10214 Hubble space telescope/advanced camera for surveys field

We present the results of a morphological analysis of a small subset of the Spitzer Wide-Area Infrared Extragalactic survey (SWIRE) galaxy population. The analysis is based on public Advanced Camera for Surveys (ACS) data taken inside the SWIRE N1 field, which are the deepest optical high-resolution imaging available within the SWIRE fields as of today. Our reference sample includes 156 galaxies detected by both ACS and SWIRE. Among the various galaxy morphologies, we disentangle two main classes, spheroids (or bulge-dominated galaxies) and disc-dominated ones, for which we compute the number counts as a function of flux. We then limit our sample to objects with Infrared Array Camera (IRAC) fluxes brighter than 10 μJy, estimated ~90 per cent completeness limit of the SWIRE catalogues, and compare the observed counts to model predictions. We find that the observed counts of the spheroidal population agree with the expectations of a hierarchical model while a monolithic scenario predicts steeper counts. Both scenarios, however, underpredict the number of late-type galaxies. These observations show that the large majority (close to 80 per cent) of the 3.6- and 4.5-μm galaxy population, even at these moderately faint fluxes, is dominated by spiral and irregular galaxies or mergers

The nuclear and extended mid-infrared emission of Seyfert galaxies

We present subarcsecond resolution mid-infrared (MIR) images obtained with 8-10 m-class ground-based telescopes of a complete volume-limited (DL<40 Mpc) sample of 24 Seyfert galaxies selected from the Swift/BAT nine month catalog. We use those MIR images to study the nuclear and circumnuclear emission of the galaxies. Using different methods to classify the MIR morphologies on scales of ~400 pc, we find that the majority of the galaxies (75-83%) are extended or possibly extended and 17-25% are point-like. This extended emission is compact and it has low surface brightness compared with the nuclear emission, and it represents, on average, ~30% of the total MIR emission of the galaxies in the sample. We find that the galaxies whose circumnuclear MIR emission is dominated by star formation show more extended emission (650+-700 pc) than AGN-dominated systems (300+-100 pc). In general, the galaxies with point-like MIR morphologies are face-on or moderately inclined (b/a~0.4-1.0), and we do not find significant differences between the morphologies of Sy1 and Sy2. We used the nuclear and circumnuclear fluxes to investigate their correlation with different AGN and SF activity indicators. We find that the nuclear MIR emission (the inner ~70 pc) is strongly correlated with the X-ray emission (the harder the X-rays the better the correlation) and with the [O IV] lambda 25.89 micron emission line, indicating that it is AGN-dominated. We find the same results, although with more scatter, for the circumnuclear emission, which indicates that the AGN dominates the MIR emission in the inner ~400 pc of the galaxies, with some contribution from star formation.Comment: 27 pages, 12 figures, accepted by MNRA

SHARDS: Constraints on the dust attenuation law of star-forming galaxies at z~2

We make use of SHARDS, an ultra-deep (<26.5AB) galaxy survey that provides optical photo-spectra at resolution R~50, via medium band filters (FWHM~150A). This dataset is combined with ancillary optical and NIR fluxes to constrain the dust attenuation law in the rest-frame NUV region of star-forming galaxies within the redshift window 1.5<z<3. We focus on the NUV bump strength (B) and the total-to-selective extinction ratio (Rv), targeting a sample of 1,753 galaxies. By comparing the data with a set of population synthesis models coupled to a parametric dust attenuation law, we constrain Rv and B, as well as the colour excess, E(B-V). We find a correlation between Rv and B, that can be interpreted either as a result of the grain size distribution, or a variation of the dust geometry among galaxies. According to the former, small dust grains are associated with a stronger NUV bump. The latter would lead to a range of clumpiness in the distribution of dust within the interstellar medium of star-forming galaxies. The observed wide range of NUV bump strengths can lead to a systematic in the interpretation of the UV slope ($\beta$) typically used to characterize the dust content. In this study we quantify these variations, concluding that the effects are $\Delta\beta$~0.4.Comment: 13 pages, 11+2 figures, 3 tables. MNRAS, in pres

A 15 µm selected sample of hHigh-z starbursts and AGNs

We report results from our Spitzer GO-1 program on IRS spectroscopy of a large sample of Luminous Infrared Galaxies and quasars selected from the European Large Area ISO Survey (ELAIS). The selected ELAIS sources have a wide multi-wavelength coverage, including ISOCAM, ISOPHOT, IRAC and MIPS (from SWIRE), and optical photometry. Here we present the sample selection and results from the IRS spectroscopy