580 research outputs found

    Preliminary Water Assessment Reports of The Test Basins of The Watch Project

    Get PDF
    This report presents the initial plans of the case studies how they link to rest of the Watch project and on which water resources they will focus. This report will function as the basis for further discussions on how to improve the integration of the case studies within the project and to develop a more general protocol for each of the case studies. Currently 5 catchments are used within the Watch project, they differ in climatic and hydro-geological features and expected climate changes: the Glomma River basin (Eastern Norway), the upper Guadiana basin (Central Spanish Plateau), the Nitra River basin (central Slovakia), the Upper-Elbe basin (part of the Elbe River) and the island of Crete. Also the water resources issues vary over these cases. Agricultural (and domestic) water use is under pressure in the Mediterranean catchments probably aggravating with the expected increase in drought frequency under future climate. The Norwegian catchment provides hydropower services under threat of precipitation increase rather than decrease. The central European catchments are threatened mainly by increased variability, i.e. increased frequencies of extremes in a densely populated environment, and river flow may need additional buffers (reservoirs) to reduce floodrisk and store water for dry period

    APPLICATION OF BIOMECHANICS TO THE PREVENTION OF OVERLOAD INJURIES IN ELITE SOCCER PLAYERS.

    Get PDF
    Structural alterations of the foot and inadequate design of sports footwear, as well as overtraining, have been determined to be risk factors for overload injuries during sports practice. A biomechanical analysis protocol was designed to study both, the foot and sports footwear statically and dynamically. This protocol was applied on 47 soccer players of the Spanish Premier League. Amongst the results we should point out that 53.3% of the players had cavus feet. 14.8% of the players deformed the boots. 44.7% of the players studied registered high pressures over the metatarsal heads. and 19.1 % registered high ones at the first toe. 44.7% of the players showed an excessive supination pattern. The data obtained gave us information about the static and dynamic patterns of the elite soccer player. With the individual information the assessment of suitable footwear was carried out for each player. The correct application of this protocol could be used in the diagnosis or prevention of overtraining and in the detection of foot and gait pathologies

    Adolescents Who Intend to Change Multiple Health Behaviours Choose Greater Exposure to an Internet-delivered Intervention

    Get PDF
    Despite a growth of Internet-delivered interventions, exposure rates to such interventions are still low. In total, 35,104 adolescents participated in the E-MOVO project: an Internet-delivered lifestyle intervention aimed at multiple health behaviours. By means of multilevel analyses, we demonstrated the relationship between intention to change behaviour and adolescents' exposure to E-MOVO's functionalities. There was a clustering of intention to change risk taking behaviours in an unhealthy way and energy balance-related behaviours in a healthy way. This should be taken into account with the design of Internet-delivered interventions. AD - Maastricht University, The Netherlands. [email protected]. FAU - Crutzen, Rik AU - Crutzen R FAU - de Nooijer, Jascha AU - de Nooijer J FAU - Candel, Math J J M AU - Candel MJ FAU - de Vries, Nanne K AU - de Vries NK LA - eng PT - Journal Article PL - England TA - J Health Psychol JT - Journal of health psychology JID - 9703616 SB - I

    Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379

    Full text link
    [ES] Los materiales compuestos de matriz metálica reforzados con carburos, son conocidos por su elevada resistencia a todos los tipos de desgaste, debido a la combinación de las partículas duras en una matriz metálica tenaz. Diferentes tipos de estos materiales, se han empleado en el desarrollo de nuevas herramientas de corte de altas prestaciones. La técnica de láser cladding(LC), permite obtener recubrimientos libres de defectos sobre zonas muy concretas, con un aporte de calor muy localizado. Pero en el caso de carburos de wolframio (WC), debido a la enorme absorción de energía y la diferencia de propiedades entre el metal base y la cerámica, puede producir una gran cantidad de defectos tales como grietas, poros, gran dilución de carburos, falta de adherencia, etc. El objetivo de este trabajo, es estudiar las transformaciones metalúrgicas que aparecen durante el procesado por láser de recubrimientos tipo cermet de WC10Ni, sobre acero de herramienta para trabajo en frío (EN 12379). Además se ha relacionado los parámetros de proceso con la generación de defectos. Para ello, se analiza su microestructura, composición y se obtienen perfiles de dureza en el recubrimiento y en el acero afectado por el calor. Los resultados muestran, que aunque el control de los parámetros del proceso reduce la generación de defectos, al depositar recubrimientos por solape de cordones, se produce gran cantidad de transformaciones debido a la disolución masiva de las partículas de WC y la difusión de elementos de aleación, desde el sustrato hacia el recubrimiento.[EN] Carbide metal matrix composite materials are known for a high resistance to all types of wear. It is due to a beneficial combination of properties given by hard phase particles included in a tough matrix. Different kinds of those materials have been employed in the development of new high properties cutting tools. Laser cladding (LC) technique allows obtaining an accurate defect-free coating with a low thermal affectation of the component. But in the case of WC cermet coatings due to its high laser absorption and the different mechanical and thermal properties between substrate and coating can appear a wide range of different defects as cracks, pores, massive carbide dilution and lacks of adherence. The aim of the present work is to study the metallurgical transformations during LC process of WC cermet coating on cold work tool steel substrate (EN 12379). Also it has been related process parameters with defects generation. Microstructure and composition of the coating and the heat affected zone have been analysed. Microhardness evolution profile has been obtained. Results show that although process parameters control reduce the generation of defects, in the deposition of overlapped layers appear different metallurgical transformations related with massive WC decomposition and the diffusion of alloying elements from substrate to the coating.Candel Bou, JJ.; Amigó Borrás, V.; Sampedro, J.; Bonache Bezares, V. (2011). Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379. Revista de Metalurgia. 47(4):355-364. doi:10.3989/revmetalm.0964S355364474Zhang, H., Wang, G., Luo, Y., & Nakaga, T. (2001). Rapid hard tooling by plasma spraying for injection molding and sheet metal forming. Thin Solid Films, 390(1-2), 7-12. doi:10.1016/s0040-6090(01)00910-5Cadenas, P., Rodriguez, M., & Staia, M. H. (2007). Effect of the post heat treatment on the sliding wear resistance of a nickel base coating deposited by high velocity oxy-fuel (HVOF). Revista de Metalurgia, 43(1). doi:10.3989/revmetalm.2007.v43.i1.51Vilar, R. (1999). Laser cladding. Journal of Laser Applications, 11(2), 64-79. doi:10.2351/1.521888Vicario, I., Soriano, C., Sanz, C., Bayón, R., & Leunda, J. (2009). Optimización del proceso de aporte de recubrimientos anticorrosión de Stellite 6 producidos mediante plaqueado láser. Revista de Metalurgia, 45(1), 14-19. doi:10.3989/revmetalm.0708Chen, C.-C. A., & Duffie, N. A. (1996). Development of an automated surface finishing system (ASFS) with in-process surface topography inspection. Journal of Materials Processing Technology, 62(4), 427-430. doi:10.1016/s0924-0136(96)02447-8Lim, L. ., Ming, Q., & Chen, Z. . (1998). Microstructures of laser-clad nickel-based hardfacing alloys. Surface and Coatings Technology, 106(2-3), 183-192. doi:10.1016/s0257-8972(98)00525-8Wang, P.-Z., Qu, J.-X., & Shao, H.-S. (1996). Cemented carbide reinforced nickel-based alloy coating by laser cladding and the wear characteristics. Materials & Design, 17(5-6), 289-296. doi:10.1016/s0261-3069(97)00025-3Hidouci, A., Pelletier, J. M., Ducoin, F., Dezert, D., & El Guerjouma, R. (2000). Microstructural and mechanical characteristics of laser coatings. Surface and Coatings Technology, 123(1), 17-23. doi:10.1016/s0257-8972(99)00394-1Sidhu, B. S., Puri, D., & Prakash, S. (2005). Mechanical and metallurgical properties of plasma sprayed and laser remelted Ni–20Cr and Stellite-6 coatings. Journal of Materials Processing Technology, 159(3), 347-355. doi:10.1016/j.jmatprotec.2004.05.023St-Georges, L. (2007). Development and characterization of composite Ni–Cr+WC laser cladding. Wear, 263(1-6), 562-566. doi:10.1016/j.wear.2007.02.023Przybyłowicz, J., & Kusiński, J. (2001). Structure of laser cladded tungsten carbide composite coatings. Journal of Materials Processing Technology, 109(1-2), 154-160. doi:10.1016/s0924-0136(00)00790-1Wu, P., Du, H. M., Chen, X. L., Li, Z. Q., Bai, H. L., & Jiang, E. Y. (2004). Influence of WC particle behavior on the wear resistance properties of Ni–WC composite coatings. Wear, 257(1-2), 142-147. doi:10.1016/j.wear.2003.10.01

    Evaluation of superficial oxidation layer of Ti6Al4V laser cladding coatings

    Full text link
    [ES] Se ha estudiado la in¿uencia de los parámetros de procesado sobre la oxidación super¿cial y propiedades mecánicas de diferentes recubrimientos de Ti6Al4V. La gran reactividad química del polvo de titanio junto a la elevada temperatura que se alcanza producen gran variedad de colores en los óxidos formados. Esta oxidación puede tener un efecto perjudicial sobre el comportamiento en servicio, por lo que su evaluación es fundamental. Aunque la in¿uencia del procesado en el color de los óxidos formados es clara, no existe una relación sencilla que explique sus propiedades mecánicas. Por ese motivo se ha seguido una metodología basada en la microscopia, microanálisis por espectroscopia de longitud de onda (WDS) y nanoindentación. Los resultados indican que no hay diferencias importantes en la dureza y módulo elástico entre dos recubrimientos que presentan diferentes colores de oxidación[EN] It has been studied the in¿uence of processing parameters on the super¿cial oxidation and mechanical properties of different coatings of Ti6Al4V. The high chemical reactivity of titanium powder, and the high temperature reached during laser processing, produces a great variety of colors in the oxides formed. This oxidation can have a detrimental effect on the behavior in service so that its evaluation is essential. Although the in¿uence of processing on the color of the oxides formed is clear, there is no simple relationship to explain its mechanical properties. For this reason it has been applied a methodology based on microscopy, microanalysis wavelength spectroscopy (WDS) and nanoindentation. The results indicate no signi¿cant differences in hardness and elastic modulus between two coatings with different colors of oxidation.Los autores agradecen al Ministerio de Ciencia e Innovación por la financiación de esta investigación a través de los proyectos MAT2008-06882-C04-03/04 enmarcados en el Programa de Materiales del Plan Nacional.Amigó Borrás, V.; Candel Bou, JJ.; Amado, J.; Yañez, A. (2010). Evaluación de la oxidación superficial de recubrimientos de Ti6Al4V obtenidos por recubrimiento por láser. Revista de Metalurgia. 46(Extraordinario):13-18. https://doi.org/10.3989/revmetalm.02XIIPMSS131846Extraordinari

    Wear behaviour of WC plasma sprayed coatings wi th micro and nanostructured powders

    Get PDF
    El objetivo de este trabajo es estudiar el comportamiento a desgaste de distintos recubrimientos de WC sobre acero inoxidable mediante proyección por plasma atmosférico. Se proyectan dos tipos de polvos comerciales con base cobalto (12 %) y níquel (10 %), con el objeto de analizar la influencia de la matriz e incluso del espesor del recubrimiento. Los recubrimientos obtenidos se caracterizan microestructuralmente por microscopía electrónica de barrido y difracción de rayos X. La caracterización tribológica de los recubrimientos se realiza mediante ensayos pin-on-disc contra bolas cerámicas de alúmina (2.400 HV) y nitruro de silicio (1.600 HV), sin lubricación, obteniéndose las tasas de desgaste y la evolución del coeficiente de rozamiento. Las pistas de desgaste y los residuos generados se caracterizaron mediante Microscopía Electrónica de Barrido, MEB. Los resultados muestran diferentes mecanismos de desgaste en cada par de material ensayado en función de la matriz y de la naturaleza de la bola empleada en el ensayo, encontrándose mayores tasas de desgaste con bola de nitruro de silicio. En una segunda fase, se obtienen recubrimientos, con dos polvos base cobalto cuyos tamaños de partícula son micrométrico y nanométrico, respectivamente, con el objetivo de estudiar la influencia del tamaño de partícula inicial sobre las propiedades a desgaste del recubrimiento. Los resultados obtenidos ponen de manifiesto una mayor resistencia al desgaste de los recubrimientos obtenidos con polvos nanoestructurados, bajo condiciones de carga elevadas, mientras que para cargas bajas ambos recubrimientos presentan un comportamiento similar a pesar de las diferencias microestructurales apreciadasThe aim of the present work is the study of wear behaviour of different WC coatings deposited on stainless steel substrate by means of atmospheric plasma spraying (APS). Two types of WC commercial powders, with different metal binder (12% Cobalt and 10% Nickel) have been deposited in order to analyse the influence of the metal matrix and thickness of the coating in tribological properties.The microstructure of the depositions was characterized using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). On the other hand, tribology characterization of the coatings was made by pin-on-disk wear tests against alumina (2400HV) and silicon nitride (1600HV) ceramic balls, without lubrication. Wear rates and friction coefficient evolution have been calculated. Finally, wear tracks and wear debris have been analysed with the help of SEM.The results of each pair of tested materials show different mechanisms of wear related to the nature of the ball that has been used, obtaining higher wear rates with silicone nitride ball..In a second phase of the study, in order to examine the influence of the initial particle size on the wear properties of the coatings, cobalt based coatings have been analysed with different initial particle size (micrometric and nanometric particles).Results show that nanostructured coatings have higher wear resistance than microstrutured ones for high loads. However for low loads, behaviour is similar in spite of the microstructural differences appreciate
    corecore