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Použití speciálních kotoučů u rozmítacích pil
Železný, Antonín
Circular saw blades are the most common woodworking tools in wood practice. This thesis describes the mechanical instability of saw blades and consequently their noise. When modificating saw blades it is possible to avoid partially these problems and achieve the maximum cutting quality and productivity. The thesis also examines the impact of the noise on human body and proposes measures designed to reduce noise of the saw blades. In the experimental part of the study we are solving the impact of the speed, the type of gearing, feed speed and type of wood swept noise level and frequency of the disc wheels oscillation.
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Study of bearing noise regarding accuracy of machining
Studýnka, Pavel ; Sabo, Karol (referee) ; Klapka, Milan (advisor)
This bachalor thesis deals with connection between the quality of surface of raceways of a bearing and vibrations in operation. This thesis describes basic geometrical parameters of a bearing that have main influence on its resulting quality and vibrations. It presents methods to evaluate the quality of the raceways surfaces and their connection between them. As a part of the thesis is an experiment, which should prove, what is the connection between the measuring of quality of the surface of raceways and measuring the vibrations of bearings during the process, by the way used in the company KOYO Olomouc. The quality of raceways is evaluated on a measuring device MUK-F 300 and vibrations on IL 100R/2000.
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Comparison of noise generated by differently constructed vents
Bernard, Jan ; Doložílek, Miroslav (referee) ; Jedelský, Jan (advisor)
This diploma thesis deals with comparing noise levels of three side vents of different constructions, which are used for distribution and directing of ventilation air in a cabin of an automobile. The fundamental knowledge of the physical and physiological acoustics is described in the introduction part of this study. Following the introduction part there is a brief explanation of the car air conditioning system (HVAC system) as well as are explained the acoustic properties of specific elements of this system. The study also deals with dividing ventilation vents and describes the vast traceable types of automobile vents. Prior to the description of the experiment, which was conducted as a part of this study, the procedures and results of the measurements carried out in other theses are explained. Measurement of noise levels of the compared vents was carried out in a semi-anechoic chamber under the ČSN ISO 3475 standardization. To clarify increase of noise generated by the vent in an interior of an automobile, additional measurement of noise was carried out in a cabin of Porsche Cayenne 2018. From the gathered results we can conclude that under the constant flow, (of 60 square meters per hour) louder vents are those with higher pressure loss. This pressure loss is dependant primarily on the speed of the flow in the vent, as well as on the number and the adjustment of the deflectors. In a cabin of an automobile, the noise produced by the vent is negligible in comparison with total noise in an interior of a car. However, in the area surrounding the air flowing out from the vent, (approximately 0,7 meters from it) the level of acoustic pressure increases significantly.
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Aspects impact trends in the operation technology of civil aviation aircraft
Korytář, Jan ; Šplíchal, Miroslav (referee) ; Chlebek, Jiří (advisor)
The aim of the work is a general description of the effects on air traffic and aircraft. The first part of the work is devoted to a brief description of the development of individual technical parameters and performance of aircraft from the 1920s to the present with an assessment of the effects. The second part of the work is about the influence of current requirements and the third part is a general view of the future development of construction and technology for more economical and environmentally friendly air transport
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Sound emission directivity model
Zdvyhal, Marian ; Hájek, Roman (referee) ; Hejčík, Jiří (advisor)
This diploma thesis solves creation of a computing model of sound propagation for determination of acoustic pressure level around multiple point sound source with consideration of sound directivity of each source (compresor and fan). Thesis contains neccesary theoretical knowledge for creation of computing model and basics of sound measuring, theoretical computing model, measurement data of real unit and model configuration for real measured values. Computing code of the model in Visual Basic for MS Excel is a part of the thesis.
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