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Processing of electromagnetic and acoustic emission signals during mechanical stressing of solids
Šopík, Martin ; Holcman, Vladimír (referee) ; Koktavý, Pavel (advisor)
Electromagnetic emission and acoustic emission are physical phenomena evoked in non-conductive material by the sudden release of energy that generate rising cracks in material structure. The significant is a fact that these emission signals are detected already in stadium of materials loading whereof can be used e.g. at non-destructive diagnostics of building materials and constructions. In the appropriate manner processing of the emitted signals then make possible to obtain valuable informations for study physical properties of cracks. Master’s thesis describes methods designed for important signal data ascertainment in time, frequency even time-frequency domain. It can be e.g. start time, maximum value, dominant frequency in spectrum etc. All these methods are implemented into main program. Next load is formularization of source signal transformation which is given by used measuring circuit. Analytical method is chosen for solving. It means finding out reserve electrical circuit with constant element values. Resultant circuit approaches original circuit with less square error than existing way. The signal transformation is described by differential equation of second order with constant coefficients. MATLAB software is used for all computations and projections.
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Practical verification of EMAT transducer parameters
Zlámal, Michal ; Havránek, Zdeněk (referee) ; Beneš, Petr (advisor)
The challenge is familiar with EMAT transducers, their basic characteristics and principles of operation. Inclusion of the theoretical knowledge acquired in Semester work 1 is based on the practical measurement of the frequency characteristics of transmitting and receiving part of laboratory made EMAT transducers. Based on the measured results should be followed by an improved design of sensor to achieve higher sensitivity with the appropriate shape of frequency response. For generating of exciting signal is expected to use LabVIEW programme environment. For credible results of the measurements in a broad range is needed to make broadband power amplifier for the transmitting and low-noise broadband amplifier for receiving part of EMAT transducer.
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Application of electromagnetic and acoustic emission signals for localization of cracks generated during mechanical stressing of solids
Burděj, Václav ; Sadovský, Petr (referee) ; Koktavý, Pavel (advisor)
Terms of acoustic emission (AE) and electromagnetic emission (EME) designated physical effects and also as diagnostic methods based on these effects. These effects are caused by generated cracks in materials that rank among non-destructive techniques of material diagnostics. The advantage of them is that they do not affect the measured object and give us information about the current dynamic state of a tested material. One disadvantage of these effects is that they provide very low energy of signal emissions and make it difficult for broader usage. It is expected better localization of cracks in non-conductive materials by connecting of these two techniques (diagnostics). There are designed and described new methods for crack detection with usage of AE and EME signals in this work. Also there is description of measuring arrangement intended of crack detection and experimental sample for checking accuracy of methods for crack detection. There was performed comparison of accuracy of methods in crack detection.
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One-Pass Authenticated Encryption
Homer, Miloslav ; Rudolf, Bohuslav (advisor) ; Hajný, Jan (referee)
The topic of this thesis are mask based one-pass authenticated encryption schemes with associated data. Formal security requirements (AUTH and PRIV), scheme requirements as well as mask system requirements are specified. The- orems regarding fulfillment of security requirements are proven given specified scheme assumptions. The proof utilizes the game-hopping technique. The the- sis contains enumeration of masking systems as well as a selection of schemes with verification that requirements are fulfilled. Last but not least, this thesis presents an attack on the OPP scheme. Recommendation on fixing this scheme is also provided. 1
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Practical verification of EMAT transducer parameters
Zlámal, Michal ; Havránek, Zdeněk (referee) ; Beneš, Petr (advisor)
The challenge is familiar with EMAT transducers, their basic characteristics and principles of operation. Inclusion of the theoretical knowledge acquired in Semester work 1 is based on the practical measurement of the frequency characteristics of transmitting and receiving part of laboratory made EMAT transducers. Based on the measured results should be followed by an improved design of sensor to achieve higher sensitivity with the appropriate shape of frequency response. For generating of exciting signal is expected to use LabVIEW programme environment. For credible results of the measurements in a broad range is needed to make broadband power amplifier for the transmitting and low-noise broadband amplifier for receiving part of EMAT transducer.
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|
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Application of electromagnetic and acoustic emission signals for localization of cracks generated during mechanical stressing of solids
Burděj, Václav ; Sadovský, Petr (referee) ; Koktavý, Pavel (advisor)
Terms of acoustic emission (AE) and electromagnetic emission (EME) designated physical effects and also as diagnostic methods based on these effects. These effects are caused by generated cracks in materials that rank among non-destructive techniques of material diagnostics. The advantage of them is that they do not affect the measured object and give us information about the current dynamic state of a tested material. One disadvantage of these effects is that they provide very low energy of signal emissions and make it difficult for broader usage. It is expected better localization of cracks in non-conductive materials by connecting of these two techniques (diagnostics). There are designed and described new methods for crack detection with usage of AE and EME signals in this work. Also there is description of measuring arrangement intended of crack detection and experimental sample for checking accuracy of methods for crack detection. There was performed comparison of accuracy of methods in crack detection.
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|
|
Processing of electromagnetic and acoustic emission signals during mechanical stressing of solids
Šopík, Martin ; Holcman, Vladimír (referee) ; Koktavý, Pavel (advisor)
Electromagnetic emission and acoustic emission are physical phenomena evoked in non-conductive material by the sudden release of energy that generate rising cracks in material structure. The significant is a fact that these emission signals are detected already in stadium of materials loading whereof can be used e.g. at non-destructive diagnostics of building materials and constructions. In the appropriate manner processing of the emitted signals then make possible to obtain valuable informations for study physical properties of cracks. Master’s thesis describes methods designed for important signal data ascertainment in time, frequency even time-frequency domain. It can be e.g. start time, maximum value, dominant frequency in spectrum etc. All these methods are implemented into main program. Next load is formularization of source signal transformation which is given by used measuring circuit. Analytical method is chosen for solving. It means finding out reserve electrical circuit with constant element values. Resultant circuit approaches original circuit with less square error than existing way. The signal transformation is described by differential equation of second order with constant coefficients. MATLAB software is used for all computations and projections.
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