18 research outputs found

    Analysis of Lateral Displacements in Large Railway Viaducts Under Traffic Loads. Impact on Ride Safety and Passenger Comfort.

    Get PDF
    The increasing design speed of the new high speed lines and the stringent requirements on track alignment parameters are leading to a sustained increase of the number of railway viaducts. The relevant standards impose limiting values on lateral vibrations. Both the Spanish and European standards establish a minimum value for the first natural frequency of lateral vibration of a span, that should not be lower than fh0 = 1,2 Hz. This limit was originally proposed by ERRI committee D181, which assessed the lateral forces in railway bridges. This limit was proposed in order to avoid lateral resonance in railway vehicles going across the structure, taking into account that the frequencies of lateral vibration of railway vehicles are, in general, not greater than 1,0 Hz. In the case of large continuous viaducts with high piers, the lateral deformations occurring during a train pass-by can be significant and the natural frequencies of the first mode of vibration of the deck can be very low. In these cases it is not clear whether the required verifications must be applied to spans considered independently, to several successive spans or to the whole viaduct. There is currently no analysis methodology allowing to assess this situation and check the viaduct design against the requirements of ride safety and passenger comfort. This paper analyzes the lateral deformations of a large continuous viaduct and the infrastructure vehicle interaction effects due to the circulation of freight trains and several types of high speed train sat different speeds. The application of this methodology will allow an optimized design of viaducts with significant lateral deformations that cannot be justified only by using the simplified criteria of the current applicable standards. In such cases, the compliance with standards may lead to over dimensioning or in other cases to neglect the limits without the adequate verification of the proper infrastructure behavior once it has been commissioned. As it is the case for vertical deformations, for which the European standards require the assessment of dynamic effects, we stress the need for a dynamic analysis of the effects of lateral deformations in large railway viaducts

    A study of the lateral dynamic behaviour of high speed railway viaducts and its effect on vehicle ride comfort and stability

    Get PDF
    The study of the lateral behaviour of railway bridges and vehicles is an important issue on bridges with low lateral stiffness, which has been defined by ERRI (1996) as those with lateral natural frequencies below 1.2 Hz. This limit applies to the deformation of the deck in one span, and was demonstrated to be a real issue on measurements and models of bridges with open deck sections and supporting trusses, of low lateral bending stiffness for the deck. Although not included in the above category, modern long viaducts for HSR with continuous decks on tall piers may also exhibit very low lateral stiffness and frequencies, which could produce undesired effects for the comfort or even the stability of the railway vehicles. In this work a simple model has been developed and applied to consider worst-case scenarios in a representative bridge, the “Arroyo de las Piedras” viaduct in Spain. The trains considered are representative of those circulating in the Spanish HSR network, as well as a freight wagon. Threedimensional dynamic models were developed with finite elements. The actions considered include the lateral deformation of the bridge in response to vertical eccentric loads, track alignment irregularities and finally lateral motion of vehicles due to conicity of wheel-rail contact. The results show that there is, at least in this case, no cause for concern. However, for some scenarios the results in terms of lateral motion and forces are not negligible and should be considered in the design

    Determining optimal flight paths for cellular network connectivity for the transmission of real-time physiological data in support of big data analytics during airborne critical care transport

    Get PDF
    This thesis presents a methodology for determining the optimal flight paths between two geographical points based on distance and cellular reception over the path. This methodology consists of two main concepts: coverage map generation, and path planning. Coverage map generation creates a grid map of the total planning space that contains coverage information for each grid point. Coverage is calculated based on geographical and technical information regarding each cell tower in the planning area. The planning step utilises the coverage map to plan a route based on minimum distance and maximum coverage, which is then smoothed into a feasible route for an aircraft to follow. This methodology is demonstrated in an airborne critical care transport within the Province of Ontario in Canada context. Leveraging available cellular information, this methodology is used to determine optimal paths between various care centres or their closest airport. Evaluation reveals that optimal routes can be found through this methodology

    Silver-Catalyzed C-C Bond Formation between Methane and Ethyl Diazoacetate in Supercritical CO2

    Get PDF
    Even in the context of hydrocarbons’ general resistance to selective functionalization, methane’s volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH4) with ethyl diazoacetate (N2CHCO2Et) to yield ethyl propionate (CH3CH2CO2Et). The use of supercritical carbon dioxide (scCO2) as the solvent is key to the reaction’s success. Although the catalyst is only sparingly soluble in CH4/CO2 mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.Ministerio de Ciencia e Innovación (grants CTQ2008-00042-BQU, CTQ2007-65251-BQU, and CTQ2007-30762-E), the European Research Area Chemistry Programme (2nd call “Chemical activation of carbon dioxide and methane” contract no. 1736154), the Consolider Ingenio 2010 (grants CSD2006-003 and CSD2007-00006), the Institut de Chimie of the CNRS, the Junta de Andalucía (P07-FQM-2870), and the Generalitat Velenciana (ACOMP/2010/155).We dedicate this work to Professor Ernesto Carmona. Support for this work was provided by the Ministerio de Ciencia e Innovacion (grants CTQ2008-00042-BQU, CTQ2007-65251-BQU, and CTQ2007-30762-E), the European Research Area Chemistry Programme (2nd call "Chemical activation of carbon dioxide and methane" contract no. 1736154), the Consolider Ingenio 2010 (grants CSD2006-003 and CSD2007-00006), the Institut de Chimie of the CNRS, the Junta de Andalucia (P07-FQM-2870), and the Generalitat Velenciana (ACOMP/2010/155). We thank the Servicio Central de Soporte a la Investigacion Experimental (Universidad de Valencia) for access to the instrumental facilities and J. de la Rosa and A. Sanchez de la Campa (Universidad de Huelva) for ICP-MS analyses

    Stable N-heterocyclic carbene (NHC)-palladium(0) complexes as active catalysts for olefin cyclopropanation reactions with ethyl diazoacetate

    Get PDF
    The Pd(0) complexes NHCPdLn (NHC = N-heterocyclic carbene ligand; L = styrene for n = 2 or PR3 for n = 1) efficiently catalyze the olefin cyclopropanation using ethyl diazoacetate (EDA) as the carbene source with activities that improve any other previous described catalytic system based on this metal. Mechanistic studies have shown that all those catalyst precursors deliver in solution the same catalytic species (IPr)Pd(sty), a 14e, unsaturated intermediate that further reacts with EDA to afford (IPr)Pd(=CHCO2Et)(sty), from which cyclopropane is formed.We thank Prof. P. J. Pérez (Univ. Huelva) for helpful and constructive comments on these studies. We thank the Ministerio de Ciencia e Innovación (grants CTQ2008–00042BQU and CTQ2011–24502) and the Junta de Andalucía (Proyecto P07-FQM-02794) for financial support. CM thanks the MEC for a research fellowshipWe thank Prof. P.J. Perez (Univ. Huelva) for helpful and constructive comments on these studies. We thank the Ministerio de Ciencia e Innovacion (grants CTQ2008-00042BQU and CTQ2011-24502) and the Junta de Andalucia (Proyecto P07-FQM-02794) for financial support. CM thanks the MEC for a research fellowship

    The electronic archive in the digital administration: 23 Conference of University Archives, 21-23 June 2017, A Coruña

    No full text
    Ponencias y experiencias empresa de las 23 Jornadas de Archivos Universitarios, 21-23 de junio de 2017, A Coruña. ISBN: 978-84-9749-680-3. DOI https://doi.org/10.17979/spudc.9788497496803[Resumen] El libro reúne las ponencias y experiencias empresa presentadas, además de las conclusiones aprobadas, en las 23 Jornadas de Archivos Universitarios, celebradas entre el 21 y 23 de junio de 2017 en A Coruña. Las ponencias tratan varios de los principales aspectos que afectan a la implantación de la administración digital y el consecuente establecimiento del archivo electrónico: el marco jurídico-administrativo introducido por las leyes estatales 39 y 40 de 2015; la introducción de modelos conceptuales de descripción archivística; y la preservación digital a largo plazo, así como la dificultad para calcular sus costes. Además, se tratan los casos concretos de la implantación de la administración y archivo electrónico en Galicia y Portugal. Las experiencias empresa muestran diversos enfoques de participación del sector privado en la mencionada implantación. Esta participación se concreta tanto en la definición del modelo de gestión documental como en proporcionar herramientas informáticas y de conservación de documentos a largo plazo. El libro incluye las conclusiones aprobadas en las 23 Jornadas de Archivos Universitarios
    corecore