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Noise impact of combustion engine exhaust systems
Ptáček, Petr ; Knotek, Jiří (referee) ; Zubík, Martin (advisor)
This bachelor’s thesis is focused on creating a research study about noise of combustion engine exhaust systems. Introducing of this work coves all parts of common exhaust systems while mostly focused on silencers. It further describes several methods of measuring the noise established by legislation and at its end it deals with a noise impact of exhaust system treatments.
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The Noise Spectroscopy of Radiation Detectors Based on the CdTe
Zajaček, Jiří ; Štourač, Ladislav (referee) ; Hájek, Karel (referee) ; Grmela, Lubomír (advisor)
The main object of this work is noise spectroscopy of CdTe radiation detectors (-rays and X–rays) and CdTe samples. The study of stochastic phenomenon and tracing redundant low-frequency noise in semiconductor materials require long-term measurements in time domain and evaluate suitable power spectral densities (PSD) with logarithmic divided frequency axes. We have used the means of time-frequency analysis derived from the discrete wavelet transform (DWT) and we have designed the effective algorithm for PSD estimation, which is comparable with an original analog method. CdTe single crystal with Au contacts we can imagine as a series connection of two Schottky diodes with a resistor between them. The bulk resistance at constant temperature and other constant parameters changes due to the carrier concentration changing only. The p-type CdTe sample shows metal behavior with every temperature changes. Semiconductor properties of the sample begin to dominate just after some period of time. This behavior is caused by the hole mobility changing. The voltage noise spectral density of 1/f noise depends on the quantity of free carriers in the sample. All the studied samples have very high value of low frequency noise, much higher than it should have been according to Hooge’s formula. The excess value of low frequency noise is caused by the low carrier concentration within the depleted region.
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Low noise pavement surfaces
Zítka, Patrik ; Dašek, Ondřej (referee) ; Hýzl, Petr (advisor)
This bachelor´s thesis focuses on the use of low-noise road surfaces, due to a constant increase of traffic noise nowadays. Within this work different types of roadways are analyzed and their advantages and disadvantages are shown. Additionally, the basic measuring methods of the traffic noise are described and summarized. Finally the procedures and results of the measurements on noise emissions on low-noise surface VIAPHONE® are discussed.
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Sound level meter for embedded systems
Stejskal, Tomáš ; Schimmel, Jiří (referee) ; Botta, Miroslav (advisor)
The aim of this work is the design and implementation of a sound level meter for emdedded systems. It is designed sound level meter sensor. This sensor includes a microphone, microphone preamplifier and ADC. This sensor is connected to a development kit STM32F4 Discovery, where sound is processed. It is processed filtration, time weighting, calculation of sound leve and loudness weighting. The sound level is then sent via the serial communication USART. This thesis includes a theoretical analysis of noise and its human perceptions. It also describes the development platform used.
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Měření hladiny intenzity zvuku zařízeními s operačním systémem iOS
SVITIČ, Daniel
The main topic of this thesis is usage of mobile devices as noise meters for physics laboratory projects. The main interest is to compare the measurements from the mobile device (iOS based platform) to a calibrated noise measuring system. The outcome is then discussed whether the mobile devices are suitable for demonstration of acoustic phenomena. The thesis includes as well a plan for a model lesson, in which students are supposed to measure noise levels with iPads.
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Selection of the optimal VBD geometry for a given technology
Šuga, Samuel ; Jaroš, Aleš (referee) ; Fiala, Zdeněk (advisor)
This thesis is focused on testing the roughing of different geometries of negative D-type tools during turning long thin parts with a slenderness ratio of 15 or more. 5 tools were selected for this task. Data from the cutting process was measured using a dynamometer, accelerometer and microphone for sound recording. The results are evaluated using FFT analysis and other signal processing methods as graphical outputs. The aim is to select the most suitable type of geometry for this application.
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Noise associated with the rail wheel
Mareš, Adam ; Řehák, Kamil (referee) ; Rec, Matouš (advisor)
The issue of noise associated with rail transport, focusing primarily on noise from the wheel – rail contact, is examined mainly in connection with rail transport, but also concerns tram transport in cities and, to a lesser extent, funicular railways. The noise of rail transport is one of the reasons why it is perceived negatively by the public, even though it offers many advantages over other modes of transport, such as environmental friendliness, travel comfort, travel speed and more. This is one of the reasons why it is necessary to focus on noise in rail transport and to understand, research and further develop and improve the whole issue as well, both in the area of passive and active noise control measures. For this reason, the aim of this work is to provide a comprehensive overview of the issue. The work therefore deals with the issue of noise in a comprehensive way, from the theoretical definition of noise, through noise sources and their distribution to noise measurement and the use of numerical methods for its evaluation and determination of appropriate preventive and anti-noise measures.
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Wind power plant
Šponiarová, Petra ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The electricity production from renewable sources is a very current topic. It also includes the electricity made by wind power plants, which the bachelor’s thesis concentrates on. An extensive research study was conducted to provide an overview of wind turbine types. Concerning wind power plants, apart from their visual impact, noise and vibration connected to their operating is an often discussed issue. The construction of a wind turbine stands for the most important role in reducing such unwanted effects. Technical experiments following specific standards and recommendations are performed to assess the impact of wind turbines-emitted noise and vibration on humans. In order to assess noise and vibration of a wind turbine a technical experiment is proposed, which uses different approaches to determine the critical components. The selection of a suitable measuring equipment and the choice of location for its subsequent use are important parts of the design. At last, the use of wind power plants is critically reviewed.
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Noise of Wind Turbine
Honzíček, Štěpán ; Prokop, Aleš (referee) ; Janoušek, Michal (advisor)
Bachelor’s thesis summarizes nowadays wind energy condition in the Czech Republic and in the world. It describes current construction of modern horizontal axis wind turbine and specifically deals with wind turbine noise sources - mechanical and aerodynamic. It typifies measurement method and follow up analysis. Concluding part narrates possibility noise effects on human health.
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Acoustic properties of road markings
Drnovský, Ondřej ; Caudr, Michal (referee) ; Radimský, Michal (advisor)
The thesis deals with verifying the acoustic properties of road markings in real conditions the vehicle travels. It contains basic information about the acoustics of the sources of traffic noise and methods of measuring noise. Below are the main information about the horizontal signposts and its impact on safety. The practical part contains descriptions of results, estimation of measurement and subsequently implemented economic assessment.
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