ICT platforms in support of future railway systems

The predicted growth of transport, especially in European railway infrastructures, is expected to introduce a dramatic increase in freight and passenger services by the end of 2050. To support sustainable development of these infrastructures, novel data-driven Information and Communication (ICT) solutions are required. These will enable monitoring, analysis and exploitation of energy and asset information for the entire railway system including power grid, stations, rolling stock and infrastructure. To address these challenges, we propose a dynamically reconfigurable advanced communication platform enabling connectivity between a variety of monitoring devices and computational resources through a heterogeneous network infrastructure. The connectivity, coordination and collaboration required is provided, on an on-demand basis in accordance to the"br/"cloud computing paradigm. The benefits of this platform in the end-to-end service delay and power consumption are quantified over the 5G Bristol is Open network topology. Document type: Contribution for newspaper or weekly magazin

Contribution à l'étude des perturbations conduites dans les chaînes de traction ferroviaire (développement d'une méthode d'analyse harmonique pour l'étude de la compatibilté avec les circuits de voie)

Dans l'exploitation des chemins de fer, la sécurité du trafic repose sur le système de signalisation et de surveillance automatique des trains. Dans certains cas de figure le système de signalisation peut être la victime des perturbations électromagnétiques générées par les engins de traction. Le couplage entre le système de signalisation et l'engin est très fort, car les deux utilisent les rails comme support pour les transferts d'énergie et d'information. D'où la possibilité d'interférence entre les signaux du système de détection des trains et les harmoniques du courant de traction. Le but de cette thèse est de contribuer au travail de conception d'un engin de traction, en donnant des outils nécessaires à la prévision de ses niveaux d'harmoniques, dès la phase de conception. Dans le premier chapitre sont énoncés les principaux composants d'un système ferroviaire, avec une description détaillée du fonctionnement de la signalisation, et les éventuels problèmes de compatibilité électromagnétique. Le deuxième chapitre est consacré à la description de topologies des chaînes de conversion d'énergie, destinées à la traction et utilisées actuellement chez ALSTOM. Dans le troisième chapitre est abordé le calcul des spectres générés par chaque convertisseur statique faisant partie des topologies décrites au chapitre deux. La méthode de modélisation choisie est illustrée à l'aide de deux applications. Le quatrième chapitre aborde le phénomène d'interaction entre les convertisseurs et le processus de génération d'harmoniques qui en découle. Le calcul et l'évolution du spectre du courant absorbé par deux onduleurs connectés en parallèle montre le phénomène de couplage entre convertisseurs. Un formalisme général de résolution de systèmes "multi-convertisseurs" dans le domaine fréquentiel est conçu et illustré par deux exemples. Deux systèmes de convertisseurs statiques utilisées en traction ferroviaire sont résolus numériquement à l'aide d'une méthode itérative de type Newton.In railroad exploitation, the traffic safety relies on the signalling system and on the automatic train supervision system. In particular configurations the signalling system can be the victim of electromagnetic disturbances generated by traction vehicies. The coupling between the signalling system and the vehicie is very strong, since both use the rails as physical support for energy and information flow. It results the possibility of perturbation of the signalling systern by the vehicle current harmonics. The goal of this thesis is to contribute to the design work of traction drives, by giving the tools necessary to the forecast of their harmônics levels, from the design phase. In the first chapter, the main components of a railway system are mentioned, with a detailed description of signalling system operation, and the possible problems of electromagnetic compatibility. In the second chapter are described the traction drives topologies which are used currently et ALSTOM Transportation. In the third chapter is calculated the current spectra generated by each static inverter described in chapter two. The selected modelling method is illustrated by two applications. The fourth chapter approaches the phenomenon of interaction between converters and their harmonic generation process. The current spectrum calculation of two parallel connected inverters shows the phenomenon of coupling between converters. A general frequency domain formalism for resolution of "multi-converters" systems is conceived and illustrated by two examples. Two systems of static inverters used in railway traction are solved numerically with a Newton type iterative method.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Fire modeling in a nonventilated corridor

The main objective of this study was to determine the effect of fire in a nonventilated corridor. A real-scale model of a corridor has been modeled in Fire Dynamics Simulator(F.D.S.) in order to determine the evolution of indoor temperatures, the visibility and the oxygen quantities during a fire. The start time of a sprinkler has also been determined. The use of sprinklers in buildings has become a necessity and a requirement imposed by technical norms. The provision of this type of installation has become a common feature in buildings with a high fire risk, with two main effects: fire extinction and protection of structural and partition elements from high temperatures[1

Numerical Model Development of the Air Temperature Variation in a Room Set on Fire for Different Ventilation Scenarios

Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements’ dimensions, burner heat release rate variation) were imposed to the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model. Besides the air temperature, at this point, other essential parameters were determined in the entire experimental space: indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. We found that if the ventilation rate increases, the indoor temperatures in that specific point decrease, and the sprinkler is activated later or, in some cases, it might never be activated. However, this conclusion is not valid for the entire analyzed space, as the ventilation system alongside the natural air movement imposes specific air speed and specific temperature distribution inside the analyzed space

Fluorimetry compared to spectrophotometry for uranium evaluation in liquid waste

<p>Uranium concentration levels in surface waters are of great importance because uranium presents both chemical and radiological hazard to the environment. The subject of this article is to establish that spectrophotometric method for uranium evaluation in effluents collected from liquid waste treatment generated during fabrication of nuclear fuel elements could be replaced by the optical fluorimetric technique. Both methods are briefly described. The comparison of the two methods was carried out with regard to international standards and national regulations offering from a statistical point of view a useful approach to compare two analytical measurement techniques. This methodology can be applied to any other measurement procedures. A discussion about the compliance of the fluorimetric analytical method with the mandatory discharge level of uranium concentration in surface waters is also presented.</p

Comparative study on microhardness between friction stir welding and tungsten inert gas assisted friction stir welding of pure copper

Welding copper and its alloys is usually difficult to achieve by conventional fusion welding processes because of high thermal diffusivity of copper, which is at least 10 times higher than most steel alloys. In order to reduce the increased temperature loss, it would be advantageous to use a process that is carried out at lower temperatures. Friction Stir Welding (FSW) is a solid state joining process that involves the joining of two metal pieces at the molecular level without melting and was explored as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (TIG - tungsten inert gas) which generates and adds heat to the process. The research includes two experiments for the FSW process and two experiments for TIG assisted FSW process. It is presented the evolution of the temperature and of the axial force during the process and is determined the microhardness for each experimental case. The aim of this paper is to make known the effects of using TIG assisted FSW process on the microhardness of the pure copper joints and to present some conditions in which it is less affected

Analysis of the influence of position of welding materials on the FSW seams properties for three dissimilar aluminium alloy

Friction Stir Welding, abbreviated FSW is a new and innovative welding process. This welding process is increasingly required, more than traditional arc welding, in industrial environment such us: aeronautics, shipbuilding, aerospace, automotive, railways, general fabrication, nuclear, military, robotics and computers. FSW, more than traditional arc welding, have a lot of advantages, such us the following: it uses a non-consumable tool, realise the welding process without melting the workpiece material, can be realised in all positions (no weld pool), results of good mechanical properties, can use dissimilar materials and have a low environmental impact. This paper presents the results of experimental investigation of friction stir welding joints to three dissimilar aluminium alloy AA2024, AA6061 and AA7075. For experimenting the value of the input process parameters, the rotation speed and advancing speed were kept the same and the position of plates was variable. The exit date recorded in the time of process and after this, will be compared between them and the influence of position of plate will be identified on the welding seams properties and the best position of plates for this process parameters and materials