2,447 research outputs found
Mineralogical Characterization and Ceramic Aplication of Muds From Washing of Natural Detritic Deposits
Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasFALSEpu
Semianalytical method for contact mechanic among shaft and bearing of a submarine vehicle
En el presente trabajo, se estudia y analiza el mejor ajuste del eje del propulsor de un vehículo sumergible a su chumacera, mediante el estudio de la geometría de contacto entre dichos elementos. Para realizar este estudio, se ha aplicado un método semianalítico, basado en las normas de la cuadratura de los principales valores de Cauchy, el método de la secante, y un método numérico para la determinación del mapa tensional de las superficies en contacto entre el eje y la chumacera. Asumiendo que existen imperfecciones de micras en el mecanizado de las superficies en contacto, estas son una causa posible de daños subsuperficiales que favorecen fallos por picaduras (pitting ) o la formación y el crecimiento de las grietas por fatiga. Estos fallos afectan no solo el buen rendimiento propulsivo, sino también las condiciones de estanqueidad, con los consiguientes riesgos que ello supone para la integridad del buque. Los resultados permiten establecer los criterios de diseño en función de los módulos de Young, así como un mecanizado correcto y el ajuste de holguras posterior del sistema eje-chumacera, con lo cual se mejorala fiabilidad de dichos elementos.The present study analyzes the best attachment of the propeller shaft of a submersible to his bearing, studying geometry of contact between those elements. A semi-analytical method based on the rules of the quadrature of the main values of Cauchy, the secant method and a numerical method for determining a tension map have been applied to the study of the contact surfaces between shaft and bearing. It is assumed that there are imperfections in the order of microns when machining the contact surfaces, which can produce subsurface damage that is possible, linked to pitting and the growth of fatigue cracks. Such failures not only will influence on the proper propulsive performance, but also on the watertightness conditions, which is related to the risk of ship integrity loss. The results let us to set design criteria, which account for the Youngs module and the importance of an adequate machining and further adjustment of clearances on the shaft-bearing system, thus improving the reliability of such elements.Peer Reviewe
Growth, water relations and ion accumulation in Phlomis purpurea plants under water deficit and salinity
The effect of different levels of water deficit and salinity on physiological and morphological alterations in Phlomis purpurea plants was studied to evaluate their adaptability to such conditions. P. purpurea plants growing under greenhouse conditions were subjected to four irrigation treatments between November and May 2008: control (C, 1 dS m-1), moderate water deficit (MWD, 1dS m-1, 60% of the control), severe water deficit (SWD, 1 dS m-1, 40% of the control) and saline (S, 4 dS m-1). Aerial dry weight decreased with salinity, response that was more marked in the water deficit treatments, especially SWD. Stem diameter and leaf number were similarly reduced in both water deficit treatments, while leaf area also decreased in saline treated plants. Throughout the experiment, plant height was similar in both control and saline treated plants and was inhibited 10 weeks after application of the deficit irrigation onwards. Only at the end of the experiment were there significant differences in plant height between all treatments. Plants irrigated with saline water had higher Na+ concentrations in their leaves than in their roots and shoots, while Cl- concentrations were similar in leaves and roots, suggesting some resistance to the movement of the latter ions from root to shoots. The accumulation of salt in the leaves was associated with osmotic adjustment, which maintained midday leaf turgor in saline treated plants. However, no osmotic adjustment was observed in plants submitted to water stress. The results indicate that the effect of osmotic stress due to water deficit was more severe than the toxic effect of salt.This work was supported by the projects: CICYT (AGL 2008-05258-C02-1-2),
CDTI (IDI-20070868) and Convenio de la Consejería de Agricultura y Agua de la Región
de Murcia-UPCT-CEBAS, 2008.Peer Reviewe
Representation and factorization theorems for almost-L-p-spaces
[EN] We extend the notions of p-convexity and p-concavity for Banach ideals of measurable functions following an asymptotic procedure. We prove a representation theorem for the spaces satisfying both properties as the one that works for the classical case: each almost p-convex and almost p-concave space is order isomorphic to an almost-L-p-space. The class of almost-L-p-spaces contains, in particular, direct sums of (infinitely many) L-p-spaces with different norms, that are not in general p-convex nor p-concave -. We also analyze in this context the extension of the Maurey Rosenthal factorization theorem that works for p-concave operators acting in p-convex spaces. In this way we provide factorization results that allow to deal with more general factorization spaces than L-p-spaces. (C) 2019 Royal Dutch Mathematical Society (KWG). Published by Elsevier B.V. All rights reserved.The first and fourth authors gratefully acknowledge the support of Ministerio de Ciencia, Innovacibn y Universidades (Spain), Agencia Estatal de Investigaciones, and FEDER, under projects MTM2014-53009-P (J.M. Calabuig) and MTM2016-77054-C2-1-P (E.A. Sanchez Perez).Calabuig, JM.; Galdames, O.; Juan Blanco, MA.; Sánchez Pérez, EA. (2019). Representation and factorization theorems for almost-L-p-spaces. Indagationes Mathematicae. 30(5):930-942. https://doi.org/10.1016/j.indag.2019.04.001S93094230
Optimal extensions of compactness properties for operators on Banach function spaces
[EN] Compactness type properties for operators acting in Banach function spaces are not always preserved when the operator is extended to a bigger space. Moreover, it is known that there exists a maximal (weakly) compact linear extension of a (weakly) compact operator if and only if its maximal continuous linear extension to its optimal domain is (weakly) compact. We show that the same happens if we consider AM-compactness for the operator, and we give some partial results regarding Dunford-Pettis operators. Narrow operators-considered as a family defined by a weak compactness type property-are also analyzed from this point of view. Finally, we provide some applications of the fact that an operator from a Banach function space extends to a narrow operator if and only if it is narrow. (C) 2015 Elsevier B.V. All rights reserved.J.M. Calabuig and M.A. Juan were supported by Ministerio de Economía y Competitividad (Spain) (project MTM2011-23164). E. Jiménez Fernández was supported by Junta de Andalucía and FEDER grant P09-FQM-4911 (Spain). E. Jiménez Fernández and E.A. Sánchez-Pérez were supported by Ministerio de Economía y Competitividad (Spain) (project MTM2012-36740-C02-02).Calabuig, JM.; Jiménez Fernández, E.; Juan Blanco, MA.; Sánchez Pérez, EA. (2016). Optimal extensions of compactness properties for operators on Banach function spaces. Topology and its Applications. 203:57-66. https://doi.org/10.1016/j.topol.2015.12.075S576620
Influence of dose and route of administration on the outcome of infection with the virulent Neospora caninum isolate Nc-Spain7 in pregnant sheep at mid-gestation
Experimental infections in pregnant sheep have been focused on studying the effect of the time of challenge on the outcome of N. caninum infection, whereas the impact of the dose and route of challenge has not been studied in depth. Therefore, clinical outcome, immune responses, parasite detection and burden, and lesion severity in placental tissues and foetal brains were investigated in 90-day-pregnant sheep inoculated intravenously with 105 (G1), 104 (G2), 103 (G3), or 102 (G4) tachyzoites or subcutaneously with 104 (G5) tachyzoites of the virulent Nc-Spain7 isolate and an uninfected group (G6). Comparing challenge doses, G1 was the only group that had 100% abortion. Likewise, IFN¿ levels in G1 increased earlier than those in other intravenously infected groups, and IgG levels on day 21 post-infection (pi) were higher in G1 than those in other intravenously infected groups. Concerning vertical transmission, G1 shows a higher parasite burden in the foetal brain than did G2 and G3. Comparing routes of administration, no differences in foetal survival rate or parasite load in the foetal brain were found. Although G2 had higher IFN¿ levels than G5 on day 10 pi, no differences were found in humoral immune responses. Because the outcome after intravenous infection with 105 tachyzoites was similar to that observed after intravenous infection with 106 tachyzoites used in a previous work (100% abortion and vertical transmission), we conclude that it may be reasonable to use 105 tachyzoites administered by the intravenous route in further experiments when assessing drugs or vaccine candidates
Physiological mechanisms involved in the recovery of euonymus and laurustinus subjected to saline waters
The scarcity of water has frequently led to saline water being reused for the irrigation of ornamental shrubs. However, before the use of such waters can be expanded, the salt tolerance and other characteristics of the ornamentals involved, need to be considered along with their capacity to recover after salinity exposure. For this reason, Euonymus japonica (euonymus) and Viburnum tinus (laurustinus) plants were submitted for twenty weeks to three irrigation treatments applied at 100% water holding capacity: Control (EC<0.9dSm-1); NaCl solution, NaCl (EC: 4dSm-1); and wastewater, WW (EC: 4dSm-1). This was followed by a recovery period of eight weeks, when all the plants were watered in the control irrigation conditions. The results showed that biomass, leaf number and total leaf area of plants subjected to the saline treatments were lower than in the control at the end of both periods in both species. However, after recovery, only euonymus showed lower growth parameters than those observed in the saline period. The highest Na+ and Cl- concentrations were observed in saline plants at the end of saline period for both species, and were higher in shoots than in roots. The opposite was observed for the K+/Na+ and the Ca2+/Na+ ratios. In Laurustinus, the Ψstem did not diminish in the wastewater-irrigated plants with respect to the control, maintaining osmotic adjustment and a high Ψt, even after recovery, whereas in euonymus this did not occur at the end of recovery period. In both species the Pn and gs were similarly reduced during the saline exposure period. However, the recovery of gas exchange in laurustinus irrigated with wastewater might be closely related to the better water status of these plants. Although the aesthetic value and growth decreased in the plants of both species, the chemical properties of the waters applied had different effects in each case, especially as regards the capacity to recover from salinity. These results underline the importance to studying the physiological mechanisms involved in the recovery of plants. © 2013 Elsevier B.V.This work was supported by the projects: CICYT (AGL 2008-05258-CO2-1-2-AGR and AGL 2011-30022-CO2-01-02) and Fundación Séneca (15356/PI/10).Peer Reviewe
Fluid structural analysis of urine flow in a stented ureter
Many urologists are currently studying new designs of ureteral stents to improve the quality of their operations and the subsequent
recovery of the patient. In order to help during this design process, many computational models have been developed to simulate
the behaviour of different biological tissues and provide a realistic computational environment to evaluate the stents. However, due
to the high complexity of the involved tissues, they usually introduce simplifications to make these models less computationally
demanding. In this study, the interaction between urine flow and a double-J stented ureter with a simplified geometry has been
analysed.The Fluid-Structure Interaction (FSI) of urine and the ureteral wall was studied using three models for the solid domain:
Mooney-Rivlin, Yeoh, and Ogden. The ureter was assumed to be quasi-incompressible and isotropic. Data obtained in previous
studies fromex vivo and in vivo mechanical characterization of different ureters were used to fit thementioned models.The results
show that the interaction between the stented ureter and urine is negligible. Therefore, we can conclude that this type of models
does not need to include the FSI and could be solved quite accurately assuming that the ureter is a rigid body and, thus, using the
more simple Computational Fluid Dynamics (CFD) approach
MEGARA focal plane subsystems
MEGARA (Multi-Espectrografo en GTC de Alta Resolucion para Astronomia) is the future optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) for GTC. The Fiber Units are placed at one Folded Cassegrain focus and feed the spectrograph located on a Nasmyth-type platform. This paper summarizes the status of the design of the MEGARA Folded Cassegrain Subsystems after the PDR (held on March 2012), as well as the prototyping that has been carried out during this phase. The MEGARA Fiber Unit has two IFUs: a Large Compact Bundle covering 12.5 arcsec x 11.3 arcsec on sky (100 microns fiber-core), and a Small Compact Bundle, of 8.5 arcsec x 6.7 arcsec (70 microns fiber-core), plus a Fiber MOS positioner, able to place up to 100 mini-bundles 7 fibers each (100 microns fiber-core) in MOS configuration within a 3.5arcmin x 3.5arcmin FOV. A field lens provides a telecentric focal plane where the fibers are located. Microlens arrays couple the telescope beam to the collimator focal ratio at the entrance of the fibers (providing the f/17 to f/3 focal ratio reduction to enter into the fibers). Finally, the fibers, organized in bundles, end in the pseudo-slit plate, which will be placed at the entrance focal plane of the MEGARA spectrographs
- …