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Derailment risk and dynamics of railway vehicles in curved tracks: Analysis of the effect of failed fasteners 被引量:4
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作者 Silvia Morales-Ivorra Julia Irene Real +1 位作者 Cesar Hernandez Laura Montalbain 《Journal of Modern Transportation》 2016年第1期38-47,共10页
The effect of the fastener's failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicle... The effect of the fastener's failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicles in two curves with distinct characteristics. First, a 3D-FEM model of a real track is constructed, paying special attention to fasteners, and calibrated with displacement data obtained experimentally during a train passage. This numerical model is subsequently used to determine the track vertical and lateral stiffness. This study evidences that although the track can practically lose its lateral stiffness as a consequence of the failure of 7 consecutive fasteners, the vehicle stability would not be necessarily compromised in the flawed zone. Moreover, the results reveal that the uncompensated acceleration and the distance along which the fasteners are failed play an important role in the dynamic behavior of the vehicle-track system, influencing strongly the risk of derailment. 展开更多
关键词 Railway dynamics Fasteners Derailment Curved track
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Development of a vehicle-track interaction model to predict the vibratory benefits of rail grinding in the time domain 被引量:2
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作者 Julia Irene Real Clara Zamorano +1 位作者 José Luis Velarte Antonio Enrique Blanco 《Journal of Modern Transportation》 2015年第3期189-201,共13页
Imperfections in the wheel-rail contact are one of the main sources of generation of railway vibrations. Consequently, it is essential to take expensive corrective maintenance measures, the results of which may be unk... Imperfections in the wheel-rail contact are one of the main sources of generation of railway vibrations. Consequently, it is essential to take expensive corrective maintenance measures, the results of which may be unknown. In order to assess the effectiveness of these measures, this paper develops a vehicle-track interaction model in the time domain of a curved track with presence of rail corrugation on the inner rail. To characterize the behavior of the track, a numerical finite element model is developed using ANSYS software, while the behavior of the vehicle is characterized by a unidirectional model of two masses developed with VAMPIRE PRO software. The overloads obtained with the dynamic model are applied to the numerical model and then, the vibrational response of the track is obtained. Results are validated with real data and used to assess the effectiveness of rail grinding in the reduction of wheel-rail forces and the vibration generation phenomenon. 展开更多
关键词 Corrugation · Dynamic overloads · Finiteelement method · Vibrations
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Soil mineral nitrogen dynamics in fallow periods in a rainfed semiarid Mediterranean agricultural system
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作者 Awais SHAKOOR Àngela D.BOSCH-SERRA +2 位作者 Antonio LIDON Damián GINESTAR Jaime BOIXADERA 《Pedosphere》 SCIE CAS CSCD 2023年第4期622-637,共16页
Rainfed agricultural systems in semiarid Mediterranean environments are subject to erratic but often heavy rainfall events.As an agronomic practice,fallow periods can be included even within the existing European Unio... Rainfed agricultural systems in semiarid Mediterranean environments are subject to erratic but often heavy rainfall events.As an agronomic practice,fallow periods can be included even within the existing European Union common policy for crop diversification.This study aimed to quantify the effects of previous mineral fertilization on soil mineral nitrogen(N_(min))content and potential nitrate leaching during no-till fallow periods of crop rotation.The Leaching Estimation and Chemistry Model(LEACHM)was used for soil N_(min)prediction after fallow.During fallow periods,N_(min)measured in the soil profile increased by an average of 125 kg N ha^(-1),whereas the model showed an average increase of 95 kg N ha^(-1).The amount of nitrogen(N)leached was estimated to be 11–38 kg N ha^(-1).The N balance simulated using LEACHM might differ from the actual situation.The calibrated LEACHM underestimated soil N_(min)after a drought period followed by soil water replenishment,probably due to a pulse in soil C and N mineralization caused by the wetting of dry soil,but overestimated soil N_(min)after occasional rainy spells when soil quickly became saturated,probably due to occasional nitrous oxide emissions not being fully accounted for by the model and specific preferential water flow,which might lead to greater nitrate leaching than that simulated by LEACHM using the convection-dispersion equation.The results show that soil N_(min)measurements after fallow periods cannot be well predicted by LEACHM.The findings of this study provide a support for fertilization planning for crop rotation systems including a fallow period to avoid overfertilization in the following cropping season and reduce N environmental impacts. 展开更多
关键词 crop rotation Latin Hypercube-One factor at a Time(LH-OAT)method Leaching Estimation and Chemistry Model(LEACHM) mineral fertilizer nitrogen balance nitrogen environmental impacts nitrogen leaching soil water
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