Multi-Sensor System For Level Measurements With Optical Fibres

A system for measuring liquid level in multiple tanks using optical fibre technology has been developed. The oil field service industry can benefit from this intrinsically safe technology. Plastic optical fibre (POF) sensor heads are excited by a 650 nm laser. Laser diodes are housed in ST connectors to obtain compact and rough prototypes and these connectors are also used in the fibre pigtails. Optical multiplexing is used to increase the measuring safety area. POF splitters and connectors are used to combine all the receiving sensor head fibres in a single one. Frequency division multiplexing is used to address each sensor head. The global system is controlled through a user friendly software application running in a PC connected to the system via an RS-232 port. A scalable prototype with a range greater than 2 meter, good linearity, better than 1.5% FS (full scale), high accuracy and resolution is developed using a unique lens to collimate and focus the light. Measurements are taken to validate the designs. Up to 8 sensor heads can be connected in the present implementation. But a greater number of sensors can be allocated with minor modifications in the electronics.Universidad Carlos III de MadridPublicad

Nonsingular charged black holes \`{a} la Palatini

We argue that the quantum nature of matter and gravity should lead to a discretization of the allowed states of the matter confined in the interior of black holes. To support and illustrate this idea, we consider a quadratic extension of General Relativity formulated \`{a} la Palatini and show that nonrotating, electrically charged black holes develop a compact core at the Planck density which is nonsingular if the mass spectrum satisfies a certain discreteness condition. We also find that the area of the core is proportional to the number of charges times the Planck area.Comment: 10 single column page

Does functional soil microbial diversity contribute to explain within-site plant beta-diversity in an alpine grassland and a <i>dehesa</i> meadow in Spain?

Questions: Once that the effects of hydrological and chemical soil properties have been accounted for, does soil microbial diversity contribute to explain change in plant community structure (i.e. within-site beta-diversity)? If so, at which spatial scale does microbial diversity operate? Location: La Mina in Moscosa Farm, Salamanca, western Spain (dehesa community) and Laguna Larga in the Urbión Peaks, Soria, central-northern Spain (alpine grassland). Methods: The abundance of vascular plant species, soil gram-negative microbial functional types and soil chemical properties (pH, available phosphorus, and extractable cations) were sampled at both sites, for which hydrological models were available. Redundancy analysis (RDA) was used to partition variation in plant community structure into hydrological, chemical and microbial components. Spatial filters, arranged in scalograms, were used to test for the spatial scales at which plant community structure change. Results: In the case of the dehesa the diversity of soil gram-negative microbes, weakly driven by soil pH, contributed to a small extent (adj-R2 = 2%) and at a relative medium spatial scale to explain change in plant community structure. The abundance of a few dehesa species, both annual (Trifolium dubium, Vulpia bromoides) and perennial (Poa bulbosa, Festuca ampla), was associated with either increasing or decreasing soil microbial diversity. In the alpine meadow the contribution was negligible. Conclusions: Microbial diversity can drive community structure, though in the hierarchy of environmental factors structuring communities it appears to rank lower than other soil factors. Still, microbial diversity appears to promote or restrain individual plant species. This paper aims to encourage future studies to use more comprehensive and insightful techniques to assess microbial diversity and to combine this with statistical approaches such as the one used here

Kinetic study of pilot-scale supercritical CO2 extraction of rosemary (Rosmarinus officinalis) leaves

NOTICE: This is the author’s version of a work that was accepted for publication in Journal of Supercritical Fluids. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Supercritical Fluids, 55 (2011). http://dx.doi.org/10.1016/j.supflu.2010.09.030Rosmarinus officinalis (rosemary) extracts were obtained in a supercritical pilot-scale plant. Based on experimental information available in the literature for analytical or low-scale processes, extraction temperature and pressure were selected to be 313 K and 30 MPa. At these extraction conditions, the kinetic behavior of the pilot-scale overall extraction curve were determined with respect to yield, antioxidant activity and carnosic acid content. The overall extraction curve was represented using Sovova’s model; the average deviation between measured and calculated yields was lower than 2%. Mass transfer coefficients in the fluid and solid phases were determined and were compared with previous data reported in the literature for low-scale rosemary supercritical extraction. A two-stage depressurization procedure was accomplished and the effect of both on-line fractionation and extraction time on the antioxidant activity of the samples collected was studied. The antioxidant activity of the different fractions could be straight correlated with the carnosic acid content with a regression coefficient of 0.92This work has been financed by Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (ALIBIRD-S2009/AGR-1469) and project FUN-C-FOOD, CSD2007-00063 (CONSOLIDER-INGENIO) from Ministerio de Ciencia e Innovación, Spain

New scalar compact objects in Ricci-based gravity theories

Taking advantage of a previously developed method, which allows to map solutions of General Relativity into a broad family of theories of gravity based on the Ricci tensor (Ricci-based gravities), we find new exact analytical scalar field solutions by mapping the free-field static, spherically symmetric solution of General Relativity (GR) into quadratic f(R) gravity and the Eddington-inspired Born-Infeld gravity. The obtained solutions have some distinctive feature below the would-be Schwarzschild radius of a configuration with the same mass, though in this case no horizon is present. The compact objects found include wormholes, compact balls, shells of energy with no interior, and a new kind of object which acts as a kind of wormhole membrane. The latter object has Euclidean topology but connects antipodal points of its surface by transferring particles and null rays across its interior in virtually zero affine time. We point out the relevance of these results regarding the existence of compact scalar field objects beyond General Relativity that may effectively act as black hole mimickers

Sensores con fibra óptica de plástico para la medida remota de nivel

4 págs, 9 figs.-- Presentado en: 3ª Reunión Española de Optoelectrónica (OPTOEL'03), Leganés (Madrid), 14-16 julio 2003.La industria demanda cada vez más métodos de medida que sean intrínsecamente seguros para aplicarlos en entornos industriales, como pueden ser atmósferas inflamables; y que eviten, en la medida de lo posible, el daño ecológico. Por ejemplo, en muchas gasolineras la necesidad de rellenar los depósitos de combustible se fija mediante control visual. Sin embargo, mientras el tanque permanece abierto se emiten a la atmósfera compuestos orgánicos volátiles (COV) que perjudican tanto la capa de ozono como la salud del operario que realiza la comprobación. La emisión de este tipo de compuestos constituyó en el año 1998 el 20% de la emisión total de contaminantes. En la actualidad, países como Méjico financian el desarrollo e instalación de dispositivos electrónicos para evitar los problemas mencionados anteriormente.En nuestro grupo se ha desarrollado un sistema multisensor para medida de nivel que se basa en el empleo de fibra óptica de plástico (FOP) en la cabeza sensora y como medio de transmisión en la red óptica. Se pueden tomar medidas en varios tanques o distintos puntos en un mismo tanque, utilizando multiplexación por división de frecuencia y acopladores direccionales de fibra óptica. En esta contribución se discute el principio de funcionamiento de dicho sensor y, a partir del modelo propuesto, se estudia la influencia que sobre la respuesta del sensor tiene la modificación de diferentes parámetros de la cabeza sensora, buscando aquellas configuraciones que permitan optimizar la respuesta del sensor. En primer lugar se describen brevemente los distintos bloques del sensor para pasar a presentar el modelo y su discusión.Este trabajo ha sido financiado por la Comunidad de Madrid (CAM-07T-0011-2001).Publicad

Influence of glycerin and lecithin inclusion in the diet on liver characteristics and lipid fraction in the serum of brownegg laying hens at 55 week of age

The effects of the inclusion of raw glycerin (GLYC) and raw lecithin, in the diet (23 to 55 wk) on liver characteristics and various serum lipid fractions were studied in brown egg-laying hens at 55 wk of age. The control diets were based on corn, soybean meal, and 4% supplemental fat and contained 2,750 kcal AMEn/kg, 16.5% CP, and 0.73% digestible Lys. The diets were arranged as a 2 × 3 factorial with 2 levels of GLYC (0 and 7%) and 3 animal fat to lecithin ratios (4:0, 2:2, and 0:4%). Each treatment was replicated 8 times and the experimental unit was a cage with 10 hens. At 55 wk of age, 2 hens per cage replicate were randomly selected, weighed individually, and slaughtered by CO2 inhalation. Liver was immediately removed and weighed and the color recorded by spectrophotometry. In addition, blood samples from one bird per replicate were collected from the wing vein and the concentration of total cholesterol, low and high density lipoprotein cholesterol, and triglycerides were determined. The data were analyzed as a completely randomized design and the main effects of GLYC and lecithin content of the diet and the interactions were determined. No interactions between GLYC and lecithin content of the diets were detected for any of the variables studied. Liver characteristics and serum lipid traits were not affected by the inclusion of GLYC in the diet. The substitution of animal fat by lecithin, however, reduced the redness (a* 14.9 to 13.8) and yellowness (b* 8.60 to 7.20) values of the liver (P < 0.05) but did not affect the content of serum lipid fractions. It is concluded that the inclusion of GLYC and lecithin in the diet did not affect liver size or serum lipid fraction. However, the inclusion of lecithin reduced the a* and b* value of the live

Caracteres geoquímicos y mineralógicos del yacimiento de Sn y Au de Montejo (Salamanca)

[Resumen] El yacimiento situado al S. E. de la Provincia de Salamanca está constituido por una serie de filones de cuarzo brechificado de dirección E-W, subverticales y encajados en materiales pertenecientes al Complejo Esquistograuváquico (Formación Monterrubio, dominando en esta zona esquistos, grauvacas y microconglomerados). Fue explotado durante los años 40 y 50 para Sn y esporádicamente para Au. Se han estudiado al microscopio 80 preparaciones pulidas y transparentes seleccionadas en cuatro sondeos de 250 metros, calicatas y antiguas escombreras, con el fin de caracterizar paragénesis, sucesión de la mineralización y alteraciones hidrotermales relacionadas. También se ha realizado un muestréo en las zonas mineralizadas y con alteración hidrotermal para su estudio geoquímico. Se han analizado: Au, As, Sb, Bi, Cu, Pb, Zn, Sn, Rb, Sr y Ba en 40 muestras. Las relaciones intereleme~ntales más evidentes son: Au-Sn-Bi y Cu-Sb. Por otro lado, se correlacionan los resultados geoquímicos con los diversos tipos de alteraciones hidrotermales.[Abstract] This tin-gold deposit is located in the SE Salamanca province. Mineralization is associated with several quartz-veins and breccias in metamorphic terrains of Precambrian-Cambrian ages (<<Complejo Esquistograuváquico»). Were studied microscopically 80 samples of four drillings (250 m deep) and other surface sampIes. It is presented mineral paragenesis and wall-rocks alterations relationed with mineralization. The geochemical stady include determinations of Au, As, Sb, Bi, Cu, Pb, Zn, Sn, Rb, Sr and Ba. A factor analysis on the geochemical data stablished the fo11owing associations: Au-Sn-Bi and Cu-Sb