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This work presents an analysis and a design methodology for a DC–DC LLC resonant converter applied to off-line LED driving. An investigation regarding the main design parameters that influence the LED low-frequency (LF) ripple has been carried out. The study was based on a mathematical analysis of the converter and employs numerical algorithms to solve a set of equations that accurately describe the converter behavior. Based on this analysis, a novel design methodology that allows for LF current ripple prediction has been devised. A numerical model has been developed to determine the LF current ripple transmission in DC–DC LLC resonant converters and provide a methodology for designing the bus capacitance in two-stage off-line LED power supplies. The work shows that the design of the LLC resonant converter for off-line LED driving is a trade-off between the converter efficiency and the LF ripple transmission. Experimental results were taken from two 46-W laboratory prototypes considering two different design goals: one for LF ripple reduction and another aiming at the highest converter efficiency and better power quality. Furthermore, the design of a two-stage LED driver based on an LLC converter taking into account the LF ripple transmission is also presented. [ABSTRACT FROM AUTHOR]

Karst aquifers are valuable groundwater resources whose management requires the use of functioning hydrogeological models. The KARSYS approach provides an explicit 3D conceptual model of the geometry and the functioning of karst aquifers that has been successfully applied in Swiss and Slovenian aquifers. In this work, KARSYS is applied in a complex geological area: the Picos de Europa National Park (Spain). The hydrogeological 3D model (500 km) shows an alpine karst aquifer compartmentalized into 32 groundwater bodies dammed up by subvertical barriers creating elevated saturated zones (water tables at 1153 m asl) and lower ones (water tables at 145 m asl). The recharge is through 18 spring catchment areas. The groundwater flows to the saturated zones pass through vertical to inclined trajectories, and phreatic flows are oriented toward NW, NE and N. KARSYS can be applied to any geologically complex area at a regional scale, although the geological structure should be simplified and the precision in some places is low. Nevertheless, KARSYS helps to identify the hydrogeological behavior of karst areas and is a useful guide for future hydrogeological researches. [ABSTRACT FROM AUTHOR]

The Vivero fault is crustal-scale extensional shear zone parallel to the Variscan orogen in the Iberian massif belt with an associated dip-slip movement toward the hinterland. To constrain the timing of the extension accommodated by this structure, we performed zircon U-Pb LA-ICP-MS geochronology in several deformed plutons: some of them emplaced syntectonically. The different crystallization ages obtained indicate that the fault was active at least between 303 ± 2 and 287 ± 3 Ma, implying a minimum tectonic activity of 16 ± 5 Ma along the fault. The onset of the faulting is established to have occurred later than 314 ± 2 Ma. The geochronological data confirm that the Vivero fault postdates the main Variscan deformation events in the NW of the Iberian massif and that the extension direction of the Late Carboniferous-Early Permian crustal-scale extensional shear zones along the Ibero-Armorican Arc was consistently perpendicular to the general arcuate trend of the belt in SW Europe. [ABSTRACT FROM AUTHOR]