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The effect of climate conditions on wheel-rail contact adhesion
Nohel, Rostislav ; Horák, Zdeněk (referee) ; Omasta, Milan (advisor)
Presented master’s thesis is focused on the experimental research of influence of climate conditions on wheel-rail adhesion, where climate conditions are meant two parameters: ambient air temperature and air humidity. These parameters always affect wheel-raid contact and their values change significantly during the year. For presented experimental research was used tribometer Mini Traction Machine (MTM) in configuration „ball on disc“. For determination of influence climate conditions was first found out the influence of air humidity on adhesion at certain temperatures, which varied between (1 to 50) °C. These experiments were performed for two types of discs, where one disc was exposed to leaf extract contamination. After that was assembled influence of both parameters (air humidity and ambient air temperature) on adhesion in the form of a 3D map, where were distinctioned states, when condensation has occured and when didn‘t. Obtained results in this thesis will be used for optimalization of rail vehicle control systems.
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Dopady změny klimatu na četnost a intenzitu sucha na území ČR
Krejčí, Michal
The main goal of this thesis is the analysis of trends of relative atmospheric humidity, absolute atmospheric humidity and water vapor pressure from years 1981-2015. Only days without precipitation were included in the input data set. The data used in the analysis comes from eight meteorological stations located in the Czech republic: Doksany, Churáňov, Kocelovice, Kostelní Myslová, Kuchařovice, Liberec, Lysá hora and Přibyslav. The statistical significance of the trends was evaluated with the Pearson’s correlation coefficient. The results show no clear evolution of the trends of the relative humidity. On the other hand, the trends of absolute humidity and water vapor pressure show significant rising trends in July (at six stations) and November (at seven stations). The July trends are probably caused by higher temperature during summer and the cause of the November trends might be caused by higher precipitation in autumn.
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The effect of climate conditions on wheel-rail contact adhesion
Nohel, Rostislav ; Horák, Zdeněk (referee) ; Omasta, Milan (advisor)
Presented master’s thesis is focused on the experimental research of influence of climate conditions on wheel-rail adhesion, where climate conditions are meant two parameters: ambient air temperature and air humidity. These parameters always affect wheel-raid contact and their values change significantly during the year. For presented experimental research was used tribometer Mini Traction Machine (MTM) in configuration „ball on disc“. For determination of influence climate conditions was first found out the influence of air humidity on adhesion at certain temperatures, which varied between (1 to 50) °C. These experiments were performed for two types of discs, where one disc was exposed to leaf extract contamination. After that was assembled influence of both parameters (air humidity and ambient air temperature) on adhesion in the form of a 3D map, where were distinctioned states, when condensation has occured and when didn‘t. Obtained results in this thesis will be used for optimalization of rail vehicle control systems.
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