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Application of Acoustic Camera in Automotive Industry
Zicha, Marek ; Prokop, Aleš (referee) ; Janoušek, Michal (advisor)
This bachelor´s thesis “Application of Acoustic Camera in Automotive Industry” is focused on description of parts of the camera, algorithms for signal evaluation and the range of appli-cations in the automotive industry. They are also important acoustic quantities discussed and they are given sound fields in which the measurement is carried out.
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Noise Source Identification Using Nearfield Acoustical Holography
Nevole, Tomáš ; Míča, Ivan (referee) ; Schimmel, Jiří (advisor)
This master’s thesis deals with problems of noise source identification using nearfield acoustical holography (NAH). In the beginning there is the summary of basic terms and values of a sound pressure field, which is unnecessary for understanding of the theme. In the next part the thesis continues with more detailed description of the NAH technology and the historical context of its emergence. Measurement equipment which is used for scanning of sound pressure fields is also introduced. In addition, the kinds of NAH (according the shape of the wave front) are showed and the planar NAH is descripted most closely. Because of the NAH algorithms are implemented in the wave number domain (k-space), there is also a chapter focused to this problem in the thesis. There are briefly descripted some similar methods in next chapter, like statistically optimized NAH, (SONAH) and iterative NAH with recursive filtration. The main product of the thesis is the practical part represented by testing application. That is created in the Matlab environment and is able to calculate and display hologram of the scanned array by the planar NAH method using the “k-space” filter. The application supposes a planar sound source and in other cases the accuracy of the reconstruction is not guaranteed. There are also given some holograms calculated with the application.
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Acoustic Holography
Vacula, Jan ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis is focused on description and process during contactless identification of sound source for near and far field. Principles of individual methods of acoustic holography are relatively shortly described and for details of this problem (on the level of algorithm of software equipment) you can see the references below thesis, which were the basic theory of my study. The introduction was conceived like description of “acoustics world”. You can find the basic information and principles about sound propagation in space and their mathematical contain at time. For this it was essential to define quantity and their units. Subsequently there is inventory of used sensors and their own construction for this measurement. Next chapter point to some techniques of acoustic holography used in practice. It includes mainly a method NAH (Nearfield Acoustical Holography) and SONAH (Statistically Optimised Nearfield Acoustical Holography) used for near-field. For reconstruction of far-field is shown principle of a method of Beamforming and manual measurement by intensity probe. The ending is focused on a concrete application these methods on combustion engines of cars.
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Visualization of sound fields
Kovář, Petr ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
This bachelor's thesis deals with problems of acoustical field visualization using near-field acoustical holography. This method is often refered as NAH. Within the thesis the basic acoustical field variables are processed and described. Two algorithms were analysed, namely the Statistically Optimal Algorithm (SONAH) and the Iterative Algorithm using the Fourier Transform (STFT) with a K-filter (Wave-Domain Filter). These algorithms are described in detail. The outcome of the practical part of this thesis is the application for sound pressure visualization. The application is created in the LabVIEW environment from the known codes and the calculation of the sound pressure is performed with one of the two algorithms described in this thesis. From depicted acoustical maps the disadvantages of this method and differences between algorithm are shown. These algorithms are then compared according to speed of the calculation.
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Visualization of sound fields
Kovář, Petr ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
This bachelor's thesis deals with problems of acoustical field visualization using near-field acoustical holography. This method is often refered as NAH. Within the thesis the basic acoustical field variables are processed and described. Two algorithms were analysed, namely the Statistically Optimal Algorithm (SONAH) and the Iterative Algorithm using the Fourier Transform (STFT) with a K-filter (Wave-Domain Filter). These algorithms are described in detail. The outcome of the practical part of this thesis is the application for sound pressure visualization. The application is created in the LabVIEW environment from the known codes and the calculation of the sound pressure is performed with one of the two algorithms described in this thesis. From depicted acoustical maps the disadvantages of this method and differences between algorithm are shown. These algorithms are then compared according to speed of the calculation.
|
|
| |
|
|
Noise Source Identification Using Nearfield Acoustical Holography
Nevole, Tomáš ; Míča, Ivan (referee) ; Schimmel, Jiří (advisor)
This master’s thesis deals with problems of noise source identification using nearfield acoustical holography (NAH). In the beginning there is the summary of basic terms and values of a sound pressure field, which is unnecessary for understanding of the theme. In the next part the thesis continues with more detailed description of the NAH technology and the historical context of its emergence. Measurement equipment which is used for scanning of sound pressure fields is also introduced. In addition, the kinds of NAH (according the shape of the wave front) are showed and the planar NAH is descripted most closely. Because of the NAH algorithms are implemented in the wave number domain (k-space), there is also a chapter focused to this problem in the thesis. There are briefly descripted some similar methods in next chapter, like statistically optimized NAH, (SONAH) and iterative NAH with recursive filtration. The main product of the thesis is the practical part represented by testing application. That is created in the Matlab environment and is able to calculate and display hologram of the scanned array by the planar NAH method using the “k-space” filter. The application supposes a planar sound source and in other cases the accuracy of the reconstruction is not guaranteed. There are also given some holograms calculated with the application.
|
|
|
Application of Acoustic Camera in Automotive Industry
Zicha, Marek ; Prokop, Aleš (referee) ; Janoušek, Michal (advisor)
This bachelor´s thesis “Application of Acoustic Camera in Automotive Industry” is focused on description of parts of the camera, algorithms for signal evaluation and the range of appli-cations in the automotive industry. They are also important acoustic quantities discussed and they are given sound fields in which the measurement is carried out.
|
|
|
Acoustic Holography
Vacula, Jan ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis is focused on description and process during contactless identification of sound source for near and far field. Principles of individual methods of acoustic holography are relatively shortly described and for details of this problem (on the level of algorithm of software equipment) you can see the references below thesis, which were the basic theory of my study. The introduction was conceived like description of “acoustics world”. You can find the basic information and principles about sound propagation in space and their mathematical contain at time. For this it was essential to define quantity and their units. Subsequently there is inventory of used sensors and their own construction for this measurement. Next chapter point to some techniques of acoustic holography used in practice. It includes mainly a method NAH (Nearfield Acoustical Holography) and SONAH (Statistically Optimised Nearfield Acoustical Holography) used for near-field. For reconstruction of far-field is shown principle of a method of Beamforming and manual measurement by intensity probe. The ending is focused on a concrete application these methods on combustion engines of cars.
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