703 research outputs found

    Estudio mineralógico de arcillas cerámicas de la provincia de Zamora III. Yacimientos en el basamento paleozoico

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    The mineralogical propiertes of 15 samples from 8 ceramic deposits of the province oh Zamora have been studied. The deposit are localized in the Paleozoic. The tecniques useid were: cation-exchange capacity, chemical analysis, differential thermal analysis, therrnogravimetric analysis and X-ray diffraction. It is concluded that the samples from deposits XX and XXII are composed, mainly, by illite (60-80 %) and kaolinite (20-40 %). The other samples contain illite (20-60 %), kaolinite (10-40 %) and montmorillanite (15-50 %)

    On the approximation of turbulent fluid flows by the Navier-Stokes-α equations on bounded domains

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    The Navier-Stokes- equations belong to the family of LES (Large Eddy Simulation) models whose fundamental idea is to capture the influence of the small scales on the large ones without computing all the whole range present in the flow. The constant is a regime flow parameter that has the dimension of the smallest scale being resolvable by the model. Hence, when = 0, one recovers the classical Navier-Stokes equations for a flow of viscous, incompressible, Newtonian fluids. Furthermore, the Navier-Stokes- equations can also be interpreted as a regularization of the Navier- Stokes equations, where stands for the regularization parameter. In this paper we first present the Navier-Stokes- equations on bounded domains with no-slip boundary conditions by means of the Leray regularization using the Helmholtz operator. Then we study the problem of relating the behavior of the Galerkin approximations for the Navier-Stokes- equations to that of the solutions of the Navier-Stokes equations on bounded domains with no-slip boundary conditions. The Galerkin method is undertaken by using the eigenfunctions associated with the Stokes operator. We will derive local- and global-in-time error estimates measured in terms of the regime parameter and the eigenvalues. In particular, in order to obtain global-in-time error estimates, we will work with the concept of stability for solutions of the Navier-Stokes equations in terms of the L2 norm.Ministerio de Educación y Ciencia JC2011-041

    Paleoseismological analysis of late Miocene lacustrine successions in the Prebetic Zone, SE Spain

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    A paleoseismological study of late Miocene lacustrine sediments was carried out in the Neogene basins of the Prebetic Zone in Albacete (Spain). We developed a multidisciplinary methodology which could be used to extrapolate the paleoseismic data to the present day. This multidisciplinary approach includes different disciplines, i.e. stratigraphy, structural analysis, seismological analysis and paleoseismology. Paleoseismological analysis was focussed on both shallow and deep lake deposits given that these sediments behave differently in different deformation fields. The seismites formed in shallow sediments were generated by liquefaction and include: sand dikes, pillow structures and intruded and fractured gr avels. The deep lake deposits show varied structures, such as loop bedding, disturbed varved lamination, mixed layers and pseudonodules. Seismites indicate paleoearthquake magnitude intervals. The trends of the seismites are usually oriented ve ry close to the stress field trends (from the late Miocene to the Present): NW-SE and NE-SW trends. This constitutes a link between tectonics and seismites. The va rved annual sedimentation evidenced by the deep lake facies was used as a relative dating method. Mixed layers were employed as paleoseismic indicators to calculate the earthquake recurrence interval. The mean recurrence interval is close to 130 years (9446 years of total record with 73 dated events), one maximum interval of 454 years and one minimum interval of 23 years and the mean estimated magnitude value is 5.1. The Gutenberg-Richter relationship shows similar "b" values close to 0.86 from paleoseismological and seismological data. This suggests that the seismic conditions have been similar since the late Miocene

    Influence of different factors on relative air humidity in Zaragoza, Spain

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    In this study, the spatial patterns of relative air humidity and its relation to urban, geographical and meteorological factors in the city of Zaragoza (Spain) is discussed. We created a relative humidity database by means of 32 urban transects. Data were taken on different days and with different weather types. This data set was used to map the mean spatial distribution of urban dry island (UDI). Using stepwise multiple regression analysis and Landsat ETM+ images the relationships between mean UDI and the main geographic-urban factors: topography, land cover, and surface reflectivity, have been analyzed. Different spatial patterns of UDI were determined using Principal Component Analysis (PCA) (Varimax rotation). The three components extracted accounted for 91% of the total variance. PC1 accounted for the most general patterns (similar to mean UDI); PC2 showed a shift of dry areas to the SE and PC3 a shift to NW. Using data on wind direction in Zaragoza, we have found that the displacement of dry areas to the SE (PC 2) was greater during NW winds while the shift to the NW (PC 3) was produced mainly by SE winds

    Masa muscular, fuerza isométrica y dinámica en las extremidades inferiores de niños y adolescentes con síndrome de Down

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    En general se ha observado que las personas con síndrome de Down (SD) tienen valores inferiores de fuerza muscular comparados con personas sin SD. También existe un déficit de masa muscular en los adultos con SD comparados con otros sin SD. Sin embargo, ningún estudio hasta la fecha había evaluado esta masa muscular en población pediátrica. Nuestro estudio pretende poner de manifiesto si también a edades tempranas existe un déficit de masa muscular y además relacionar ambos valores. Los niños y adolescentes con y sin SD (15±3 y 14±3 años respectivamente) de nuestro estudio obtuvieron valores similares de masa muscular ajustada por talla y estadio puberal, pero el grupo con SD obtuvo valores inferiores de fuerza (p<0.05). Además de esto, el grupo con SD ejerció menos kilogramos de fuerza por cada kilogramo de masa muscular. Alguna causa fisiológica o de transmisión podría explicar esta falta de fuerza ya que, al menos en esta franja de edad no existe un déficit de masa muscular. Deberían incentivarse los programas de entrenamiento específicos para este tipo de población para comprobar si es posible un incremento en su fuerza muscular.Generally it has been observed that population with Down syndrome (DS) has lower levels of muscular strength compared with others without DS. It is also known a deficit between muscular mass between adults with and without DS. However, there are no studies until the date which evaluated muscular mass in paediatric populations. Our study pretends to show whether also in earlier ages it does exist a deficit in the muscular mass and also to relate both values. Children and adolescents with and without DS (15±3 y 14±3 years respectively) from the study had similar values of muscular mass adjusted by height and puberal status, but DS group obtained lower values in all strength parameters. In addition, DS group also performed less kilograms of strength by kilogram of muscular mass. Some physiological or transmission impairment could explain this lack of strength as it known that there are not deficit in the muscular mass. Specific and adapted for this population training programs should be promoted to check whether an enhancement in their muscular strength is possible.Peer Reviewe

    Study of turbocharger shaft motion by means of non-invasive optical techniques: Application to the behaviour analysis in turbocharger lubrication failures

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    [EN] This paper presents a novel non-invasive technique to estimate the turbocharger shaft whirl motion. The aim of this article is to present a system for monitoring the shaft motion of a turbocharger, which will be used in turbocharger destructive testing. To achieve this, a camera and a light source were installed in a turbocharger test bench with a controlled lubrication circuit. An image recording methodology and a process algorithm have been developed, in order to estimate the shaft motion. This processing consists on differentiating specific zones of the image, in order to obtain their coordinates. Two reference points have been configured on the compressor side, which help to calculate the relative position of the shaft, avoiding the errors due to structural vibrations. Maximum eccentricity of the turbocharger has been determined and it has been compared with shaft motion when it is spinning in different conditions. A luminosity study has been also done, in order to improve the process and to obtain locus of shaft position in a picture exposition time period. The technique has been applied to diagnosis of a lubrication failure test and the main results will be presented in this article: like shaft motion figures; thermodynamic variables and pictures of the shaft while it is spinning at abnormal lubrication conditions. The measuring components used in this technique have the ability to withstand the catastrophic failure of the turbocharger in this type of test. © 2012 Elsevier Ltd.Pastor, JV.; Serrano, J.; Dolz, V.; López Hidalgo, M.; Bouffaud, F. (2012). Study of turbocharger shaft motion by means of non-invasive optical techniques: Application to the behaviour analysis in turbocharger lubrication failures. Mechanical Systems and Signal Processing. 32:292-305. doi:10.1016/j.ymssp.2012.04.020S2923053

    Are the helminth communities from unisexual and bisexual lizards different? Evidences from gastrointestinal parasites of Darevskia spp. in Turkey

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    Specimens of three species of parthenogenetic lizards (Darevskia uzzelli, D. bendimahiensis,and D. sapphirina) from northeastern Turkey were examined for gastrointestinal parasites. Only one species, the nematode Spauligodon saxicolae (Pharyngodonidae), was found. The extremely low infection and diversity parameters, falling among the lowest within the Palaearctic saurians, support depauperate helminth communities for these parthenogenetic lacertid lizards. Our results suggest that parthenogenetic Darevskia follow a pattern of parasitism similar to other unisexual lizards (i.e. Aspidocelis). The low rates of infection and diversity may be explained by the decreasing opportunities for interchanging helminths rather than factors of susceptibility of unisexual hosts

    Attractive and repulsive interactions in the inelastic scattering of NO by Ar: A comparison between classical trajectory and close-coupling quantum mechanical results

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    The rotationally inelastic scattering of NO by Ar was studied on a potential energy surface at the collision energy of a high resolution experiment. The study entailed the calculationm of the state-resolved integral and differential cross sections for all the excited levels of NO in the lowest spin-orbit manifold. The quasiclassical approach was shown to satisfactorily reproduce few observations seen in both the experimental and quantum mechanical state-resolved differential cross-sections. © 2003 American Institute of PhysicsFunded by the Ministry of Science and Technology of Spain under Grants No. BQU2002-04627-C02 and No. REN 2000-1557, by the European Union through the RTN Reaction Dynamics ~HPRN-CT-1999-0007!, and by the U.S. National Science Foundation ~Grant No. CHE-9971810! The research was performed within the Unidad Asociada ‘‘Química Física Molecular’’ between the Universidad Complutense and the CSIC.Peer Reviewe
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