The Effect of Pool Length on the Results of Professional Lifeguard Saving Tests

Todos los datos que han permitido la elaboración de este estudio, han sido facilitados por la Federación Madrileña de Salvamento y Socorrismo, por lo tanto, en este apartado se agradece la inestimable colaboración de esta entidad y de su equipo docenteEn este estudio se ha seleccionado a 2.528 aspirantes a la certificación de socorrista acuático (1.798 hombres y 730 mujeres). Todos ellos han realizado las cuatro pruebas físicas de agua cronometradas que se exigen para trabajar de socorrista en piscinas, instalaciones acuáticas y medio natural en la Comunidad Autónoma de Madrid (España). Del total de los participantes, 1.887 aspirantes realizaron dichas pruebas en vaso de 25 metros y 641 lo hicieron en vaso de 50 metros. El objetivo de este estudio es conocer la influencia de la longitud del vaso en el que se desarrollan estas pruebas físicas, sobre el porcentaje de aprobados y sobre las marcas de tiempo que emplean los participantes para realizarlas. Los resultados de esta investigación demuestran que la longitud del vaso en el que se evalúa a los aspirantes a socorrista, influye significativamente sobre las marcas de tiempo que obtienen y también sobre el número de aprobadosIn this study 2.528 aspirants for aquatic lifeguard certification (1.798 men and 730 women) were selected. All the participants of the study have performed the four physical tests of chronometric water required in order to work as a lifeguard for swimming pools, aquatic and open water in the Comunidad Autónoma de Madrid (Spain). Of the whole participants, 1.887 aspirants were tested in a 25-meter pool and 641 were done so in a 50-meter pool. The aim of this study is to know the influence of the length of the pool in which these physical tests are developed, on the pass rate and on the time needed by the sample to carry them out. The results of this research show that the length of the pool in which the aspirants are evaluated, influences on the time marks obtained by them and also on the number of approved one

H.E.S.S. deeper observations on SNR RX J0852.0-4622

Supernova Remnants (SNRs) are believed to be acceleration sites of Galactic cosmic rays. Therefore, deep studies of these objects are instrumental for an understanding of the high energy processes in our Galaxy. RX J0852.0-4622, also known as Vela Junior, is one of the few (4) shell-type SNRs resolved at Very High Energies (VHE; E > 100 GeV). It is one of the largest known VHE sources (~ 1.0 deg radius) and its flux level is comparable to the flux level of the Crab Nebula in the same energy band. These characteristics allow for a detailed analysis, shedding further light on the high-energy processes taking place in the remnant. In this document we present further details on the spatial and spectral morphology derived with an extended data set. The analysis of the spectral morphology of the remnant is compatible with a constant power-law photon index of 2.11 +/- 0.05_stat +/- 0.20_syst from the whole SNR in the energy range from 0.5 TeV to 7 TeV. The analysis of the spatial morphology shows an enhanced emission towards the direction of the pulsar PSR J0855-4644, however as the pulsar is lying on the rim of the SNR, it is difficult to disentangle both contributions. Therefore, assuming a point source, the upper limit on the flux of the pulsar wind nebula (PWN) between 1 TeV and 10 TeV, is estimated to be ~ 2% of the Crab Nebula flux in the same energy range

VHE gamma-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0 with H.E.S.S

Supernova remnants (SNRs) are widely considered to be accelerators of cosmic rays (CR). They are also expected to produce very-high-energy (VHE; $E > 100$ GeV) gamma rays through interactions of high-energy particles with the surrounding medium and photon fields. They are, therefore, promising targets for observations with ground-based imaging atmospheric Cherenkov telescopes like the H.E.S.S. telescope array. VHE gamma-ray emission has already been discovered from a number of SNRs, establishing them as a prominent source class in the VHE domain. Of particular interest are the handful of SNRs whose X-ray spectra are dominated by non-thermal synchrotron emission, such as the VHE gamma-ray emitters RX J0852.0-4622 (Vela Jr.) and RX J1713-3946. The shell-type SNRs G1.9+0.3 and G330.2+1.0 also belong to this subclass and are further notable for their young ages ($\leq 1$ kyr), especially G1.9+0.3, which was recently determined to be the youngest SNR in the Galaxy ($\sim100$ yr). These unique characteristics motivated investigations with H.E.S.S. to search for VHE gamma rays. The results of the H.E.S.S. observations and analyses are presented, along with implications for potential particle acceleration scenarios.Comment: ICRC 2011 proceedings, 4 pages, 2 figures, 3 table

Computer aided design of horizontal axis turbine

This paper presents a computer-based method for modelling the blades of horizontal axis turbines using B-spline surfaces. The method uses common design parameters for the geometry of this type of turbine and produces a final set of B-spline surfaces for the geometry of the blades that can be used for the visualisation, calculations and construction of the rotor surface. The method begins with the creation of a 3D set of offsets that constitute the rotor blades based on a 2D definition of the airfoils, which is normally used in the design of different stations along the rotor blade. It also uses geometrical parameters such as the skew and rake or coning distribution. The method stresses the fitting of the blade?s leading edge, which has a significant impact on the properties of the rotor and separately models the trailing edge of the blades. B-spline curves and surfaces are used in this method because they are widely used in CAD-CAM software products and can be easily exported to other programs

Fuzzy role-based access control

RBAC (Role-Based Access Control) is a widely used access control model, which reduces the maintenance cost of classical identity-based access control. However, despite the benefits of RBAC, there are environments in which RBAC can hardly be applied. We present FRBAC (Fuzzy Role-Based Access Control), a generalization of RBAC through fuzzy relations that extends the applicability of RBAC to environments where authorization-related information is vague. Moreover, FRBAC deals with environments where the actions that can be executed over the resources have a fractional meaning, as data lying in databases and risk-based access control