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Problematika dopravního hluku.
KOLÁŘ, Jiří
This thesis deals with the issue of noise produced by road traffic in six selected areas of south bohemian communities Budweis and Třeboň. In all six areas the measurements were carried out according to the approved methodology and the results were compared with already known data measured from these locations. The results were compared with relevant legislations and standards, and possible measures were proposed in order to reduce the exposed values.
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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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Model Study of Ultrasound Effects on Fetal Development
Jaroš, Josef ; Halámek, Josef (referee) ; Hrazdíra,, Ivo (referee) ; Rozman, Jiří (advisor)
The progress in ultrasound techniques goes hand in hand with increasing of diagnostic machine acoustic outputs. Ultrasound biological effects can adversely influence the development of human fetus. Recent studies of thermal effect on biological tissues are usually based on simulation of simple ultrasound transducers. The aim of this work is to build a flexible model of diagnostic system to simulate temperature increase during fetal development. Different types of ultrasound probes were used for generation of acoustic field with simulated piezoelectric element properties. Optimized linear and phased arrays were modeled with dynamic beam steering and focus. Computer simulations were concentrated on extreme conditions in obstetric ultrasonography and 3D tissue model was compared with real ultrasound probes measurements. To detect temperature increase, the bone tissue phantom was used. Results point out potential risks for fetus with diagnostic ultrasound probes. Based on the results of this work, practical recommendations increasing safety of obstetric examinations were drawn.
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Finite element modelling of voice propagation through the vocal tract and around the human head
Tomeček, Vojtěch ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This diploma thesis deals with creating of finite element model for the analysis of acustic waves radiation through human vocal tract and through the head surrounding space. The thesis contains a short overview of the anatomy of relevant parts and a short overview of formerly published models relevant to the topic. Then the process of creating the 3D model of human head, including the vocal tract, based on CT scans, and the mesh itself follows. This is succeeded by the computational solution taking in the acount the acoustic absorption of the vocal tract walls and radiation into the open space. The results gained are compared to relevant literature on this topic. The changes in frequency spectra in specific nodes of the mesh are reviewed and compared to relevant literature on the topic. The results could be used as basis of eventual frequention corrections of microphones used for voice diagnosis or registration in general, eg of speach or singing.
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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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