2,676 research outputs found

    An optimization tool to design the field of a Solar Power Tower plant allowing heliostats of different sizes

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    The design of a Solar Power Tower plant involves the optimization of the heliostat field layout. Fields are usually designed to have all heliostats of identical size. Although the use of a single heliostat size has been questioned in the literature, there are no tools to design fields with heliostats of several sizes at the same time. In this paper, the problem of optimizing the heliostat field layout of a system with heliostats of different sizes is addressed. We present an optimization tool to design solar plants allowing two heliostat sizes. The methodology is illustrated with a particular example considering different heliostat costs.MTM2013-41286-P (Spain) MTM2015-65915-R (Spain) P11-FQM-7603 (Andalucía) TD1207 (EU COST Action

    Streptococcus parasanguinis: new pathogen associated with asymptomatic mastitis in sheep.

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    We describe two unusual cases in sheep of subclinical mastitis caused by Streptococcus parasanguinis. This bacterium has been associated with the development of experimental endocarditis; its presence at relatively high concentrations in apparently healthy sheep milk may pose a health risk in persons with predisposing heart lesions

    Comparative analysis of the serve in volleyball between the spanish championships 2005-2010

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    El objetivo fue analizar los cambios que ha experimentado el saque desde el Campeonato de España cadete masculino de 2005 al de 2010. Mediante la observación sistemática se analizaron 1594 acciones, en las cuales se midieron las siguientes variables: zona de origen, eficacia, tipo de saque, zona de recepción, función del receptor, dirección y temporalidad. Los resultados reflejaron que en los últimos años, el saque realizado por jugadores de categoría de formación ha sufrido modificaciones relevantes, tales como, mejora de la eficacia, incremento del empleo del saque en salto, y realización del saque con un carácter más táctico. Pese a la mayor aproximación del saque a los perfiles existentes en alto nivel, se recomienda que el saque de voleibol en categorías de formación se entrene en función de las características y nivel de los jugadores, evitando el mimetismo de lo que acontece en alto nivelThe aim of this research was to analyze the changes in the characteristics of the serve between the male Under-16 Spanish Championships that took place in 2005 and 2010. Through systematic observation 1594 actions were analyzed. The measured variables were: serve zone, effectiveness, serve type, reception zone, in-game role of the receptor, serve direction and timing. The results showed that in recent years, the serve performed by players at training stages has undergone significant changes, such as improved efficiency, increased use of jump serve, and execution of the serve with a more tactical role. Despite of the closest approach of the serve to the existing high level profiles, it is recommended to train the serve in volleyball training stages according to the characteristics and level of players, avoiding mimicry of what happens at a high levelEste trabajo ha sido realizado gracias al apoyo del Programa de Formación de Personal Investigador (FPI) de la Consejería de Empleo, Empresa e Innovación del Gobierno de Extremadura (España), y gracias al Ministerio de Ciencia e Innovación en el Plan Nacional de I+D+I 2008-2011 (ref. DEP2011-27503

    Composición, propiedades, estabilidad y comportamiento térmico del aceite de semilla de tamarindo (Tamarindus indica)

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    The composition, thermal stability and phase behavior of tamarind (Tamarindus indica) seed oil were analyzed to contribute to the exploration of their potential uses. The oil was extracted from the kernel of the tamarind seed with hexane, and its main physical, chemical and thermal properties were analyzed by infrared spectrometry, gas chromatography-mass spectrometry, DSC, and TGA. The results showed that the tamarind seed had a 3.76 ± 0.20% oil with a saponification index of 174.80 ± 9.87 mg KOH/g and the major fatty acids were lignoceric (20.15%), oleic (18.99%) and palmitic (11.99%). Stearic, behenic, linoleic, arachidic, and other fatty acids were also present. TGA and DSC showed that in an inert atmosphere, the triacylglycerols of tamarind seed oil (TSO) are decomposed in a single stage that starts at 224.1 °C and in an air atmosphere in three stages, initiating its decomposition at 218 °C. The TSO showed crystallization and fusion curves with a single maximum peak with Tonset and Toffset of 20.16 and ?38.8 °C and ?22.2 and 28.6 °C, respectively. The solid fat profile of the oil showed a semi-solid and liquid consistency in the ambient temperature range. The composition, thermal and phase behavior showed that TSO is potentially useful for alimentary, pharmacological, and cosmetological purposes.La composición, estabilidad y comportamiento térmico del aceite de semilla de tamarindo (Tamarindus indica) fueron analizadas con el fin de contribuir al conocimiento de sus potenciales usos. El aceite fue extraído del núcleo de la semilla con hexano y analizado mediante sus principales propiedades físicas, químicas y térmicas mediante espectrometría infrarroja, cromatografía de gases, espectroscopia de masas, calorimetría (DSC) y termogravimetría (TGA). Los resultados mostraron que las semillas del tamarindo tuvieron un contenido de aceite de 3,76 ± 0,20%, con un índice de saponificación de 174,80 ± 9,87mg KOH/g y ácidos grasos mayoritarios: Lignocérico (20,15%), oleico (18,99%), palmítico (11,99%) y en cantidades menores los ácidos esteárico, behénico, linoleico y araquídico, entre otros. El análisis mediante TGA y DSC mostró que la temperatura inicial de descomposición del aceite fue de 224,1 °C en una sola etapa en atmósfera inerte y en atmósfera de aire fue a 218 °C en tres etapas. El aceite mostró curvas de cristalización y fusión con un solo máximo, iniciándose y finalizando estos cambios de fase a 20,16 y -38,8 °C, and -22,2 y 28,6 °C, respectivamente. Estas propiedades mostraron que el aceite de la semilla de tamarindo tiene potenciales aplicaciones en alimentos y productos farmacológicos y cosméticos

    The intracluster magnetic field in the double relic galaxy cluster Abell 2345

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    Magnetic fields are ubiquitous in galaxy clusters, yet their radial profile, power spectrum, and connection to host cluster properties are poorly known. Merging galaxy clusters hosting diffuse polarized emission in the form of radio relics offer a unique possibility to study the magnetic fields in these complex systems. In this paper, we investigate the intracluster magnetic field in Abell 2345. This cluster hosts two radio relics that we detected in polarization with 1–2 GHz Jansky Very Large Array observations. X-ray XMM–Newton images show a very disturbed morphology. We derived the rotation measure (RM) of five polarized sources within ∼1 Mpc from the cluster centre applying the RM synthesis. Both, the average RM and the RM dispersion radial profiles probe the presence of intracluster magnetic fields. Using the thermal electron density profile derived from X-ray analysis and simulating a 3D magnetic field with fluctuations following a power spectrum derived from magneto-hydrodynamical cosmological simulations, we build mock RM images of the cluster. We constrained the magnetic field profile in the eastern radio relic sector by comparing simulated and observed RM images. We find that, within the framework of our model, the data require a magnetic field scaling with thermal electron density as B(r) ∝ n e (r). The best model has a central magnetic field (within a 200 kpc radius) of 2.8±0.1 μG. The average magnetic field at the position of the eastern relic is ∼ 0.3 μG, a factor 2.7 lower than the equipartition estimate

    Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei

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    We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei 19^{19}B, 22^{22}C and 29^{29}F as well as that of 34^{34}Na. In addition, the most precise determinations to date for 23^{23}N and 31^{31}Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in 22^{22}C, with a dominant ν2s1/22\nu2s_{1/2}^2 configuration, and a single-neutron halo in 31^{31}Ne with the valence neutron occupying predominantly the 2p3/2p_{3/2} orbital. Despite a very low two-neutron separation energy the development of a halo in 19^{19}B is hindered by the 1d5/22d_{5/2}^2 character of the valence neutrons.Comment: 5 page

    Evaporation residues produced in spallation of 208Pb by protons at 500A MeV

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    The production cross sections of fragmentation-evaporation residues in the reaction Pb+p at 500A MeV have been measured using the inverse-kinematics method and the FRS spectrometer (GSI). Fragments were identified in nuclear charge using ionisation chambers. The mass identification was performed event-by-event using the B-rho - TOF - Delta-E technique. Although partially-unresolved ionic charge states induced an ambiguity on the mass of some heavy fragments, production rates could be obtained with a high accuracy by systematically accounting for the polluting ionic charge states. The contribution of multiple reactions in the target was subtracted using a new, partly self-consistent code. The isobaric distributions are found to have a shape very close to the one observed in experiments at higher energy. Kinematic properties of the fragments were also measured. The total and the isotopic cross sections, including charge-pickup cross sections, are in good agreement with previous measurements. The data are discussed in the light of previous spallation measurements, especially on lead at 1 GeV

    Lactococcus lactis subsp. lactis infection in waterfowl: first confirmation in animals.

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    We report the first description, confirmed by bacteriologic and molecular (polymerase chain reaction and pulsed-field gel electrophoresis) analysis, of an infection in animals caused by Lactococcus lactis subsp. lactis, affecting waterfowl
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