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Impedance Tube for Measuring Sound Absorption Coefficient
Raška, Adam ; Sysel, Petr (referee) ; Schimmel, Jiří (advisor)
This thesis, consists of summering basic knowledge about absorption factor, methods for its measuring and construction of impedance tube for measuring with chosen method. Besides that, this thesis i salso about measuring absorbtion factor of available materials in this tube, and proposing laboratory task about absorbtion factor measurement, which should use crafted measuring equipment.
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Computational modelling of high-frequency noise inside cabin of aircraft EV-55M
Straka, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This thesis describes methods of high frequency noise and vibrations computation of cabin part of EV–55M (aircraft developed by Evektor Kunovice). There is a brief summary of methods used for determining high frequency noise and vibrations in the first part of the thesis. Detailed explanation is given for Statistical Energy Analysis (SEA) which is nowadays the most dominant method in this area. The energy balance equation is derived in this chapter and SEA parameters such as modal density, damping loss factor, coupling loss factor and power input are introduced here. Next part deals with main noise sources of propeller driven and jet aircraft and passive and active noise controls are discussed. Practical part of this thesis deals with modeling aircraft EV–55M fuselage using VA One SEA module. Two models were created. First of them is only an outside fuselage with aircraft flooring and the second one is extended by interior trim panels and is applicable for simulation of noise control treatments. Computational modeling is accompanied by experimental measurement of passive noise control material characteristics. Postprocessing of information obtained from impedance tube measurement was performed in FOAM – X. Determined characteristics of porous material were used as inputs to VA One and reduction of sound pressure level in fuselage cavities by using noise control treatment was found. In conclusion there is a summary of noise transmission paths from sources to interior cavity and some treatments of them are simulated
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Measuring system for acoustic characterisation of materials
Plánka, Mikuláš ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The diploma thesis deals with the measurement of acoustic parameters of the material using the B\&K 4206 impedance tube, specifically the absorption and reflection coefficients. The theoretical part provides a basic overview of the measurement methodology and a description of measurement quantities related to acoustic materials characterization. The measurement procedure using the PULSE LabShop software is also described in this work. The main focus of this thesis is the design and implementation of a custom open measurement system created in LabVIEW used to determine the aforementioned materials parameters. The results of the measurements using the custom implementation and the PULSE LabShop software are compared and evaluated in this diploma thesis.
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Impedance Tube for Measuring Sound Absorption Coefficient
Raška, Adam ; Sysel, Petr (referee) ; Schimmel, Jiří (advisor)
This thesis, consists of summering basic knowledge about absorption factor, methods for its measuring and construction of impedance tube for measuring with chosen method. Besides that, this thesis i salso about measuring absorbtion factor of available materials in this tube, and proposing laboratory task about absorbtion factor measurement, which should use crafted measuring equipment.
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Measurement of Sound Absorption Coefficient in Impedance Tube
Jun, David ; Nespěšný, Ondřej
The sound absorption coefficient is one of the most common quantities describing the acoustic behaviour of materials and structures intended for use in room acoustics. This contribution first shows a brief overview of techniques for measuring sound absorption coefficient. Special attention is paid to the impedance tube (often called Kundt tube) group of methods. The following is an introduction to the measurement of the transfer-function method and to a developed impedance tube prototype, including both the hardware assembly and the software implementation of the measurement.
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Vliv čalounických materiálů na akustický komfort v interiéru
Schmidtová, Terezie
This thesis documents the possibilities of elements application in interiors in order to improve the acoustic characteristics of the space and it analyses the acoustic issues in contemporary interior and factors that affect it. The aim is to compare the acoustic absorption of selected types of filling materials and upholstery composition used in its production. The thesis includes a description of sample preparation, a procedure of measurement in an impedance tube, results processing to determine the sound absorption of tested materials and a measurement of foam cells sizes using microscope and Visiocell program. Acquired values were compared with each other.
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Computational modelling of high-frequency noise inside cabin of aircraft EV-55M
Straka, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This thesis describes methods of high frequency noise and vibrations computation of cabin part of EV–55M (aircraft developed by Evektor Kunovice). There is a brief summary of methods used for determining high frequency noise and vibrations in the first part of the thesis. Detailed explanation is given for Statistical Energy Analysis (SEA) which is nowadays the most dominant method in this area. The energy balance equation is derived in this chapter and SEA parameters such as modal density, damping loss factor, coupling loss factor and power input are introduced here. Next part deals with main noise sources of propeller driven and jet aircraft and passive and active noise controls are discussed. Practical part of this thesis deals with modeling aircraft EV–55M fuselage using VA One SEA module. Two models were created. First of them is only an outside fuselage with aircraft flooring and the second one is extended by interior trim panels and is applicable for simulation of noise control treatments. Computational modeling is accompanied by experimental measurement of passive noise control material characteristics. Postprocessing of information obtained from impedance tube measurement was performed in FOAM – X. Determined characteristics of porous material were used as inputs to VA One and reduction of sound pressure level in fuselage cavities by using noise control treatment was found. In conclusion there is a summary of noise transmission paths from sources to interior cavity and some treatments of them are simulated
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