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Computational modelling of interaction between oscillating vocal folds and air flow
Pavlica, Ondřej ; Matug, Michal (referee) ; Švancara, Pavel (advisor)
Master thesis deals with creating numerical model of the human vocal folds. Calculation algorithm includes interaction between vocal chords and the air flow. Modal analysis of structural and acoustic environment, backround research of vocal folds function and summary of some published overviews of numerical models are parts of this work. Analysis of the results achieved by the numerical simulations and calculations are focused on the pressure and velocity conditions in the areas under vocal folds, between vocal folds and above vocal folds. Movement and stress analysis of individual layers of vocal folds has been made. Impact of tissue thickness on resulting behaviour has been assessed.
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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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Comparison of loudness inside and outside tractor's cabine
OPEKAR, Jiří
This bachelor's thesis is aimed at investigating the noise level in a tractor cabin and at certain distances from the tractor. Eleven tractors of different brands with power outputs ranging from 70 kW to 93 kW were selected for the study. The thesis outlines noise problems in general, the noise classification and sources, and examines the impact of noise on human health as well as the legislation concerning protection against noise. Further investigated within the study is noise in agriculture and in particular types of noise caused by certain parts of a tractor. Included are also basic tractor cab design parameters, its history, evolution and current state. The study presents characteristics of the examined tractors and describes acoustic pressure values measured inside and outside the tractor cabins. The values are presented in the form of tables and charts. Lastly, the values are compared for all the tractors within the study and the results are evaluated.
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Tractors with regard to their development and noise
KRÝSL, Zdeněk
This bachelor thesis briefly describes the history, development and manufacturers of tractors. One part of this thesis deals with the noise in general and the noise of tractors. The practical part studies the levels of noise in the spot of operation and in a certain distance form a tractor during different operation modes. The tractors were studied with respect to a long time period of their production, so that an assessment regarding the technical progress in production as well as the noise pollution affecting the operation and the people near the machine was possible.
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Sources of noise and bionoise in livestock buildings for dairy farming
BUŇATA, Miroslav
The bachelor thesis deals with the identification and measurement of noise and bionoise sources in livestock buildings for dairy farming. For this measurement were selected farms in my area: Agricultural cooperative Vysočina Želiv, SENAGRO a. s. The measurement was carried out gradually in both companies, which measured the noise and bionoise source. The results determined the minimum and maximum values of noise levels and calculated the corresponding equivalent level of acoustic pressures, which they brought to each graph. The resulting values were compared with the current legislation and in the case of long-term exceeded the maximum specified limit of noise; it was proposed steps to reduce noise levels in the workplace.
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Use of mowing tractors to maintain green spaces.
JANOUŠEK, Jan
This thesis deals with a noise pollution caused by mowing tractors during the maintenance of a green spaces. Mowing tractors Iseki SXG 22 and Starjet Exclusive 4x4 were chosen for used measurements. Measuring of noise pollution in surrounding areas has been done from five different distances and subsequently evalueted with current legislation.
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Noisiness of earth moving machines
KOLÁŘ, Štěpán
The bachelor paper deals with the measurement of acoustic pressure levels at universal earth moving machines from various manufacturers and with different power rating. For this measurement there were selected these machine types: JCB 3CX TURBO SITEMASTER and BĚLORUS 30-2621 B. The measurement was carried out not only in certain operational conditions, such as during freewheel revolutions, idling at maximum speed (at rest), working operation and during machine load (while driving) at certain distances from the machine, but also in the cab of the machine operator. The methodology was specially developed for the measurement and the resulting values were compared with valid legislation.
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The sound pressure levels at tractors of the same power
ANDĚL, Tomáš
This thesis deals with the measuring of the sound pressure levels at tractors of the same performance class. Tractors of the following types: John Deere 6230, Case IH JX 95, Steyr 9094, belonging to medium-power tractors, were selected for this specific measuring. The measuring was performed in three operating states of the tractors: at the idle speed, at the maximum no-load speed and at the load of the tractor. A special methodology was developed for these measurements. The measuring results imply that the highest influence on the noise levels of the tractors is that of the motor speed. The sound pressure levels measured at the load of the tractor were by 6.8 to 8.5 dB lower than those measured at the maximum speed. This difference results especially from the operation of the loaded tractor at a lower speed than the maximum.
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Measurement of acoustic pressure in the workplace.
ČERNÝ, Lukáš
Acoustic pressure in environment protection programs of developed countries is the one of most important issue after air and water pollution. Acoustic pressure is all around us, such like machines, traffics and some other things. It is not possible to completely stop the noise, but there are some certain ways were used to reduce it up to acceptable limits. The aim of this work is to measure the acoustic noise and find solution to reduce it. The first measurements were done indoor (workplace studio) focused on room acoustic. We measured the acoustic pressure for three heights in different places,but finally the most important results were selected and compared with respect to each others. The next measurements were performed outdoor to collect the results about spread of the noise, which were analyzed with certain limits. The main goal was to find how to safe the human health and maintain peaceful and healthy environmental.
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