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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Traffic-induced vibrations on a two span composite railway bridge : Comparison of theory and measurements

Miguel Escudero López, José January 2011 (has links)
The economic and technologic development experienced by the society in the last decades has caused the demand of a new type of faster and more comfortable transport. This type of demand has been covered by the air transport, the road transport and the railway transport. This situation where the society demands an improvement in her quality of life is the best situation for the birth of the high speed trains. Different studies carried out in the transport field have demonstrated that for distances between four hundred and one thousand of kilometres, the high speed trains provide a lower travelling times than the rest of the transports. These types of high speed trains have increased the axle loads and the average speeds, thus generally a dynamic analysis is required by the ERRI in all the railway bridges when the train speed is higher than 200 Km/h. Besides, when the train speed is going to be higher than 200 Km/h, the vibrations induced in the bridge can reduce the service life of the vehicles and structure, and generally, this fact leads to become the dynamic effect in the principal factor to take into account in order to design the structure. Therefore, an important knowledge in railway bridges dynamic is required to not to oversize the structures with the consequent economic cost. The purpose of this thesis is to study the possibility of accurately predicting the dynamic response of an existing railway bridge, subjected to the high speed train Gröna Tåget, implementing a simplified 2D finite element model with the aid of the program Abaqus. The bridge chosen is the Lögdeälv Bridge, a two spans composite bridge, located along the Bothnia Line (the new Swedish high-speed line), between the localities of Nordmaling and Rundvik. The measured eigenfrequencies due to bending modes of vibration are used for updating the model and then, these frequencies and the accelerations measured are used to compare and validate the different 2D updated models. The parameters used to update the models are; the damping coefficient of the structure, the mass and the stiffness of the bridge, and the supports stiffness. Finally it is concluded that the best model is achieved when the rotational support stiffness is modified in the two extremes supporters of the bridge.
2

Bakom bra eller dåligt : En diskursanalytisk studie av digitalisering av samhället i Biblioteksbladet 2020 / Beyond good or bad : A discourse analysis about the digitalization of society in Biblioteksbladet 2020

Anderlid, Amanda January 2021 (has links)
The aim of this thesis is to examine the usage of metaphors and language features used in the debate about the digitalization of Swedish society in a library context. The empiric material consists of 22 articles published in Biblioteksbladet from January 2020 – March 2021. The method of analyzing the material was based on Fairclough’s critical discourse analyze and Jenny Lindberg´s logics of a Catch-the-train-technological deterministic discourse (Tåget-Går-diskurs). The thesis findings showes that digitalization as phenomenon is used in a technical deterministic way in which six aspects were found valid: infrastructural, national competition oriented, user oriented, availability as access, availability as supply and a post-pandemic-oriented aspect.
3

Track Irregularities for High-Speed Trains : Evaluation of their correlation with vehicle response / Spårlägesfel för höghastighetståg : Utvärdering av deras korrelation med fordonsrespons

Karis, Tomas January 2009 (has links)
Gröna Tåget

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