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Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
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Performance of top-of-rail products in railway
Jordán, Tomáš ; Polach, Pavel (referee) ; Galas, Radovan (advisor)
Presented master’s thesis deals with a development of methodology of the top-of-rail products performance in railway with use of the real rail. The performance parameters are adhesion development with carry distance, carry distance, friction layer retentivity and product redistribution. The top-of-rail products are used to reduction of wear and noise pollution in railway. Currently used methodology in laboratory cause model distortion and unreal friction layer. Field experiments are affected by environmental conditions. As a main part of this thesis was developing of the methodology for the performance parameters study. The methodology was experimentally tested with four commercial products. An obtained knowledge was presented and discussed. As a part of the methodology was studied running-in of real rail. For measuring of shear friction on the top-of-rail was designed and realized a tribometer. The output of this work is functional sample of the tribometer and a manuscript dealing with the designed methodology.
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Proposal of Part of Information System for Selected Subject
Langer, Tomáš ; Polách, Pavel (referee) ; Luhan, Jan (advisor)
This thesis deals with the analysis, proposal and implementation of part of the information system for a selected subject, specifically the proposal of a website including a web application for content management of selected parts of the website. For a successful proposal solution it is very important the first analysis together with requirements of the contracting authority. The graphic design phase occurs after analysis and is followed by the development of the website and the application for content management. After testing and agreement of the proposal solution from the contracting authority the website and application are implemented to the server site. In the final part of the thesis an economic evaluation and benefit’s analysis of the proposal solution are done.
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Top of rail lubricant development
Skurka, Šimon ; Polach, Pavel (referee) ; Kvarda, Daniel (advisor)
Friction modification within the wheel-rail interface is an important way of achieving ecologically friendly transportation of both persons and goods. This thesis aims to develop a new TOR lubricant, which will be able to maintain suitable frictional conditions while securing minimal adhesion required for traction. All measurements were carried out on tribometer MTM in the ball-on-disc configuration. In the first step, individual components were examined. More complex compositions were measured after that and the three best of them were compared with commercial TOR lubricants. The results show a good ability of developed compositions to maintain required adhesion, reduce wear, and all of them had resistivity against over-lubrication. Lastly, the process of lubricant verification before its application in real traffic was discussed.
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Training system for clibmers
Polach, Pavel ; Sekora, Jiří (referee) ; Bubník, Karel (advisor)
The purpose of this diploma thesis was design and realisation of measuring system, enabling measuring forces between climber´s feet and holds on the climbing wall and using this measu-red values during a training of sport climber. In this thesis there are discovered possibilities about constructing this system and determina-ted basic requirements of measuring. There are also stated principles of application the strain gauges for measuring the tension. Descriptions of developping specific sensors, hardware interface and PC application are also part of this thesis. Constructed system was used for mea-suring climbers and values were analysed by using the application.
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Experimental research of fluids against icing of overhead wires
Málek, Jan ; Polach, Pavel (referee) ; Galas, Radovan (advisor)
In this thesis, commercially available anti-icing fluids were tested. A methodology of assessment was designed for the effect of anti-icing fluids on the rapidity of ice growth and its development over time. These tests were conducted on a device constructed for the purpose of the thesis. The solutions were tested for their effect on the ice adhesion to a contact wire. The effect of the solutions on the tribological behaviour of the collector strip and contact wire was described. The experiments were supplemented by mensuration of the size of the contact angle of the solutions on the copper surface. However, these fluids anti-icing effect is relatively short-term. On the contrary, the thesis shows that even a small amount of anti-icing solution on the surface of the contact wire can help to significantly lower the ice adhesion.
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Testing of Rail Lubricants Performance
Tomčová, Renata ; Polach, Pavel (referee) ; Galas, Radovan (advisor)
Top-of- rail lubricants are an effective way to control adhesion, reduce contact wear and noise in rail transport. However, despite the widespread use of these lubricants, there is currently no standard defining how to test and evaluate their performance. This work aims to develop a methodology for testing top-of-rail lubricants in a laboratory environment using a tribometer in a ball-on-disk configuration. At first, important operational parameters of experiments are analyzed and experimentally tested. These are mainly wear-in and run-in, method of application, roughness and geometric parameters of contact bodies. The result of this work is a testing methodology that guarantees good repeatability and reliability of results. In the last part of this work, the methodology is verified using commercial top-of-rail lubricants.
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Influence of physical load on electrical activity of muscles
Polach, Pavel ; Kolář, Radim (referee) ; Kolářová, Jana (advisor)
Bachelor´s thesis was focused on influence of physical load on electrical activity of muscles. The basic principles and terms from the problematics of measuring electric activity of human being were analyzed and also it was focused on mechanisms of neuromuscular system of human beings. The basic methods of measuring EMG were also mentioned in the text. Autor suggested measuring protocol, got data from a group of people, made an application and used this application to analyse measured signals. At the end of the work it was suggested statistic processing and evaluation of results.
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Development of a tribometer for the adhesion measurement on a real rail
Vodehnal, Michal ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
The submitted master’s thesis describes the development of a tribometer used to measure the adhesion of a real rail. The thesis contains an overview of the basic terms concerning wheel and rail contact. Following that, there is an overview of devicesthat are able to measure the adhesion on a real track. The author's solution includes a design of the tribometer, the proposed measurement methodology and also a description of the individual components. The result of this thesis is a functional device, verified in laboratory conditions and on a real track.
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