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Research on the load-carrying capacity of lubricating film in rolling bearings
Šmíd, David ; Čermák, Jan (referee) ; Omasta, Milan (advisor)
This diploma thesis deals with the problem of sudden contamination of the elastohydrodynamic contact by solid particles and their influence on parameters affecting the lubricating film, such as surface texture and real film thickness, especially for line contact. The contact is operated under conditions corresponding to the operation of the main wind turbine bearings, with measurable parameters supported by optical observations. The main effort of this work is to relate the influence of the flow of solid particles in the lubricant to the parameters determining the lubrication regime. For the experiments, a taper-on-disc device was constructed to simulate linear contact. Using this device, the effects of different solid particles on the damage of a sample (roughness parameters Ra and Rq) with linear contact and the influence of this altered structure on the lubricating film thickness (hmin) are experimentally described. These remarks are partially compared with the effect of particles on point contact. The result of this paper is a better understanding of the solid particle flow in the Hertzian contact region and clarification of the influence of this flow on the surface structure and associated lubricating film thickness, especially for linear contact.
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Research into the causes of very low friction between wheel and rail
Polnický, Jan ; Hajžman, Michal (referee) ; Omasta, Milan (advisor)
A low traction coefficient causes problems when starting trains, extends the braking distance, and leads to overrunning stations. These problems often occur in conditions of high humidity and low traffic. Oxides on the rail surface form a suspension with water, causing the traction coefficient to drop. This work addresses the mechanisms by which this drop is caused, based on observations using an optical tribometer. Additionally, a study was conducted to map the influence of various parameters on the drop in the traction coefficient. The tested parameters include suspension concentration, the applied amount, the type of base fluid, and others.
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Studium složení emitovaných pevných částic z domácího spalování
Lesná, Barbora ; Mravcová, Ludmila (referee) ; Doležalová Weissmannová, Helena (advisor)
The aim of this bachelor thesis is the analysis of the chemical composition of different biomass samples. Biomass samples underwent combustion in a fireplace stove, simulating combustion in domestic fireplaces. Firstly, biofuels are defined and the difference in chemical composition between wood and herbal fuels, which this thesis focuses on, is being discussed. In the following chapters, the combustion process and various types of emissions being released from the combustion of solid fuels are presented. Attention is paid to legislation and methods of measuring aerosols, then the focus is drawn to methods of their chemical analysis. The last chapters of the theoretical part focus on the health and environmental risks of solid particles that go hand in hand with being exposed to those particles. In the experimental part, the processes of sampling filters with particles, microwave decomposition of the samples. Furthermore, the thesis describes the analysis of the chemical composition of the input fuel, emitted particles and ash, in which metals were determined by the method of absorption atomic spectrometry. The concentration of solid particles on the filter is calculated here. In the discussion, individual fuels are compared according to the content of each metal.
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The effect of lubricant contamination and degradation on lubricating film behavior
Strnad, Jan ; Dzimko, Marián (referee) ; Omasta, Milan (advisor)
Lubrication contamination and degradation is one of the major causes of unexpected failure of tribological nodes. As a result, different levels of maintenance are introduced in practice, leading to a longer service life of the lubricated node. These systems often include sophisticated on-line diagnostic tools that can be used to evaluate a sample of a lubricant using certain variables such as viscosity, number of particles, humidity, dielectric constant, etc. Based on changes of these variables some systems can make corrective measures such as filtering or complete replacement of lubricant. Therefore, the aim of this experimental thesis is to determine the influence of lubrication contamination (solid particles, moisture) and degradation (oxidation) on the lubricating film behavior with respect to its limit bearing capacity. To examine the thickness of the lubricating film, friction and wear, an optical and MTM tribometer, in the ball-on-disc configuration, was used.
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DPF for SI Engines
Pohludková, Lenka ; Prokop, Aleš (referee) ; Dundálek, Radim (advisor)
This bachelor thesis deals with gasoline particulate filters. Emissions of internal combustion engines and their impact on air pollution and human health, especially the impact of particulate matter, are discussed. It also describes what these filters are made of, where they are located in the car, and explains the principle of their function and regeneration.
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The concentration of particulate matter in the air of selected areas of the city of Brno and its health risks
Bulejko, Pavel ; Čáslavský,, Josef (referee) ; Adamec, Vladimír (advisor)
Tato práce se zabývá znečištěním ovzduší pevnými prachovými částicemi v lokalitách města Brna. V teoretické části je pojednáno o možných zdrojích prachových částic, o chemickém složení a velikostní klasifikaci polétavých částic a dalších fyzikálně-chemických charakteristikách. Další část je věnována zdravotním rizikům prašnosti. V této souvislosti práce pojednává o anatomii dýchacího systému a účincích prachu na něj. Jsou taktéž rozebrány zdravotní efekty prachového znečištění, včetně uvedení možných nemocí respiračního a kardiovaskulárního systému, jejichž může být prach příčinou. V praktické části byl proveden sběr prachu. Byly vybrány celkem čtyři lokality, kde byly prováděny odběry vzorků. Následně byly stanoveny koncentrace polétavých částic PM10 a PM2,5. Dále byly u vybraných lokalit stanoveny koncentrace těžkých kovů a polyaromatických uhlovodíků vázaných na prachových částicích. V závěru bylo provedeno srovnání s legislativou a stanovena zdravotní rizika.
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The DPF and SCR systems
Novodomský, Tomáš ; Janoušek, Michal (referee) ; Dundálek, Radim (advisor)
The presented bachelor thesis deals with exhaust emission reducing systems for diesel engines. The first part is devoted to the composition of exhaust gases and emission standards. The thesis analyses the formation of solid particles, their regulation by the DPF system and its various variants. Further the principle of reducing the nitrogen oxide content in the exhaust gases by the selective catalytic reduction system is described. In the final part, there is a reflection on the future of emission reduction systems, emission standards and alternative drives.
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Technology sputtering of flue-gas
Hladík, Petr ; Brázdil, Marian (referee) ; Hrnčířová, Michaela (advisor)
The object of this bachelor’s thesis is to create a research in field of flue gas scrubbing technology. In the first part, there are briefly outlined issues of size and shape of particles present in flue gas after combustion. Next part focuses on basic general characteristics of separators. Main part treats of individual types of separators. Following chapters deal with emission limits in Czech Republic and future development of the field. Thesis is concluded by sample calculation of the cyclone separator.
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