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Adhesion modelling of grease lubricant in wheel-rail contact
Kuchař, Tomáš ; Voltr, Petr (referee) ; Kvarda, Daniel (advisor)
Currently, there are efforts to optimise the coefficient of adhesion in wheel-rail contact to reduce wear, noise and energy consumption. A project to create a digital twin for the Brno–Adamov line is being solved by ŠKODA TRANSPORTATION, a.s., the Jan Perner Transport Faculty of the University of Pardubice and the Institute of Machine and Industrial Design of the Brno University of Technology. In this thesis, within the previously mentioned project, the problem of grease retentivity was addressed, which is the distance or time for which the grease is able to efficiently lubricate the contact and thus maintain the adhesion coefficient at the desired level. The main objective of this work was to develop a model describing the effect of climatic conditions and operating parameters on retentivity of grease. The studied grease was BECHEM EcoRail 2009, which consists of bentonite thickener and a synthetic ester as a base oil. The grease was studied on a commercial Mini-Traction Machine (MTM) device in a ball on disc configuration. The effects of temperature, air humidity, load, slip, speed and lubricant quantity on retentivity were investigated. It was found that increasing load and slip caused a decrease in retentivity and could be described by using the energy absorbed by the lubricant. Increasing velocity caused a decrease in retentivity expressed in time but an increase in retentivity expressed in slip distance or number of cycles. Increasing the amount of lubricant caused a linear increase in retentivity. Increasing temperature caused an increase in retentivity, but only if the temperature was within the operating range of the grease. Air humidity only had an effect if condensation occurred, such that an increase in retentivity was observed. Dimensionless parameters were used in the model, which should make it possible to transfer the model to real scale. However, lubricant deposition to the rail and redistribution to other wheelsets was not included in the model. The model was then verified with a rail tribometer and it was shown that the model prediction was consistent with the measured results.
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Autonomous outdoor system for growing plants
Schmidt, Dominik ; Lukeš, Zbyněk (referee) ; Petržela, Jiří (advisor)
This diploma thesis deals with maintaining possibilities for appropriate climatic conditions in outdoor greenhouse. The importance for growing plants is an appropriate temperature, humidity and adequate supply of water. The aim of the study is to suggest an apparatus sustaining beforehand defined conditions in the greenhouse with minimal requirements for maintenance. Apparatus uses analogue control by applying photosezistor and thermistor. For power supply are DC-DC converters used.
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Climate testing room for personal vehicles
Málek, Ludvík ; Katolický, Jaroslav (referee) ; Štětina, Josef (advisor)
The diploma thesis deals with the design of testing equipment, a climate chamber in particular, to simulate external weather conditions. The chamber walls are made of socalled sandwich insulation panels. Based on the wall thermal properties, heat loss of the chamber was calculated. The conditioned air is supplied by a distribution channel at sides of the chamber. The exhaust air leaves the chamber in the ceiling zone. The ventilation unit is located on the ceiling. The design includes the integration of the UV lamp, simulating sunlight. The chamber will allow the weather effects on the microclimate inside a car to be studied. Furthermore, the sunlight simulations can be carried out in the chamber to detect polymers or varnish aging, and the fading of colours.
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Autonomous outdoor system for growing plants
Schmidt, Dominik ; Lukeš, Zbyněk (referee) ; Petržela, Jiří (advisor)
This diploma thesis deals with maintaining possibilities for appropriate climatic conditions in outdoor greenhouse. The importance for growing plants is an appropriate temperature, humidity and adequate supply of water. The aim of the study is to suggest an apparatus sustaining beforehand defined conditions in the greenhouse with minimal requirements for maintenance. Apparatus uses analogue control by applying photosezistor and thermistor. For power supply are DC-DC converters used.
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The effects of vegetative roofs onto the thermal stability of a building object
Majsniar, Michal ; Moudrý, Ivan (referee) ; Vimrová,, Hana (referee) ; TROJAN,, Karel (referee) ; Šťastník, Stanislav (advisor)
Dissertation deals with thermal technical assessment songs vegetation roof with moisture, the more the influence of vegetation on the roof thermal stability of the structure. The aim of this work is to demonstrate the beneficial effect of vegetation roofs, specifically growing Formation of thermo-technical point of view on the favorable temperature conditions in the building. Such speech can be captured only if it is judged-temperature profile dynamically daily operation of real marginal climatic temperatures. Using a stationary or quasi-stationary boundary climatic temperatures which are usually used for the determination of the energy performance of buildings, said effect can not be collected. Demanding simulation calculation, which apply material properties - thermal conductivity, density and thermal capacity, but gives a realistic picture of the thermal processes in progress not only in the roof structure of the building, but also across the entire circuit construction of a building. During the preparation of the dissertation was assembled machine program that works with the energy flow between rooms in the building and the surrounding environment. Furthermore calculates temperature gain of residence of persons, internal lighting and sunlight. The values of the internal environment are calculated from surface temperature, relative humidity, air exchange and, of course, the indoor air temperature with hourly weather data. In constructing the program was included in the calculation of the solar radiation both on flat and on an inclined surface. The output of the energy value and temperature conditions in individual rooms, which include not only thermal insulation but also thermal storage properties of an object. Using experimental measurements were able to demonstrate that the calculated values closely correlate real thermal processes, so it can be demonstrated through the calculated results of the vegetation roof has a favorable effect on the thermal state espe
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Toxicological Aspects of Chemical Accidents
Roman, Michal ; Vičar,, Dušan (referee) ; Mika, Otakar Jiří (advisor)
The master's thesis focuses on the toxicological aspects of chemical accidents. The aim is to determine the main acute risk of dangerous toxic chemical substances that can be escape in chemical accidents and determine their impact on life and damage to the health of the population and characterize the factors affecting the spread of these dangerous chemicals. The practical part focuses on the toxicological aspects of selected industrial pollutants.
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Process Calibrator M143 - Climatic Testing
Dojava, Václav ; Bartoň, Jan (referee) ; Havlíková, Marie (advisor)
Subject of the bachelor thesis are the climatic testing of the M143 calibrator. Theoretical section of the thesis is concerned with the analysis and description of the norms used during climatic tests of electronic devices. Thesis then continues by describing properties and functions of the M143 calibrator and the Caliber programme, which is performing automated measurement during the climatic tests, on the basis of the designed calibration procedure. Practical section of the thesis describes the designed testing points and climatic conditions, which are adjusted during the testing. In this section the testing points are implemented to the Caliber programme. Last section contains the analysis and evaluation of the measured data gained during the climatic testing. From these measured data, we are to determine, whether the M143 calibrator is within the specifications stated by the manufacturer in different climatic conditions.
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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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The effect of real condition of a rail on friction between the wheel and rail
Škubna, Michal ; Hajžman, Michal (referee) ; Omasta, Milan (advisor)
The aim of this master’s thesis is to determine the influence of the friction layer formation conditions on the rail surface on the coefficient of adhesion. Currently, laboratory studies of adhesion are carried out on simplified contact models using tribometers in a two-disc device configuration or in a ball-to-disc configuration, which does not correspond to the real behavior of the wheel-rail interface. The experiments described in this work were carried out in a laboratory environment on a sample of a real rail using a tribometer to achieve variable slip. This made it possible to measure the entire traction curves for the specific rail surface condition. Several experiments were carried out to determine the influence of climatic conditions – especially relative humidity and the effect of water on the development and composition of friction layers naturally formed on the rail. To do this, several procedures were used to achieve the individual friction layers. In addition to the influence of climatic conditions, the influence of simulated passages of rolling stock using a contact simulator was also implemented. The output of the thesis is a draft article describing the methods of preparation of friction layers and the results achieved.
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