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Qualitative comparison of MEMS vibration sensors
Hasík, Stanislav ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The aim of this bachelor thesis is a qualitative parameter validation of MEMS vibration sensors using calibration devices from the companies SPECTRA a Brüel & Kjr. First part of study deals with different types of MEMS vibration sensors on the piezoresistive, capacitive and thermal principle of operation. The study also deals with primary and secondary methods of calibration of vibration sensors and devices used for these calibration methods. The second part of the thesis is to use the calibration chains and secondary calibration methods to verify the sensitivity and temperature dependences of three particular MEMS accelerometers from the companies STMicroelectronic, MEMSIC and Panasonic. The measured characteristics are compared with catalog datasheets. In the end of the thesis are also discussed the possibility of the suppression these temperature effects.
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Noncontact temperature measurements using luminescent materials
Jedlička, Jindřich ; Nebojsa, Alois (referee) ; Ligmajer, Filip (advisor)
This diploma thesis deals with noncontact temperature measurement using luminescent materials. In the theoretical part of the thesis, luminescent materials were selected on the basis of a literature review with respect to sensitivity and operating temperature range. In the experimental part of the thesis, photoluminescence of CdSe/ZnS and GaAs quantum dots for various temperatures was measured and the relative change of luminescence parameters such as emission peak position, intensity, intensity ratio of two emission peaks, and lifetime of luminescence were determined from the measurements in agreement with expectations according to the literature. Achieving high spatial resolution would be made possible by measuring cathodoluminescence, where the luminescence spectra are obtained with an order of magnitude higher spatial resolution. These measurements and the influence of electron beam on the luminescence quality of selected materials will be subject of further experimental study.
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Noncontact temperature measurements using luminescent materials
Jedlička, Jindřich ; Nebojsa, Alois (referee) ; Ligmajer, Filip (advisor)
This diploma thesis deals with noncontact temperature measurement using luminescent materials. In the theoretical part of the thesis, luminescent materials were selected on the basis of a literature review with respect to sensitivity and operating temperature range. In the experimental part of the thesis, photoluminescence of CdSe/ZnS and GaAs quantum dots for various temperatures was measured and the relative change of luminescence parameters such as emission peak position, intensity, intensity ratio of two emission peaks, and lifetime of luminescence were determined from the measurements in agreement with expectations according to the literature. Achieving high spatial resolution would be made possible by measuring cathodoluminescence, where the luminescence spectra are obtained with an order of magnitude higher spatial resolution. These measurements and the influence of electron beam on the luminescence quality of selected materials will be subject of further experimental study.
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Computational time reversal method based on finite element method: influence of temperature
Mračko, Michal ; Kolman, Radek ; Kober, Jan ; Převorovský, Zdeněk ; Plešek, Jiří
Time reversal method is used to focus elastic waves to the location of the original source and reconstruct its source time function. The procedure consists of two steps: Frontal task and Reversal task. In the Frontal task, the medium is excited by an arbitrary source, elastic waves propagate through a body of interest and the dynamic response at few points on boundary is recorded. In the second step (say the Reversal task) the response signal is reversed in time and transmitted back into the medium resulting in focusing in the original source location. It is of practical importance to investigate a case when the medium changes its properties between the frontal and reversal wave propagation steps. An example is a problem of transferring experimentally recorded data to a computational model, where discrepancies in geometry, elastic properties and boundary conditions are expected. Our motivation is to develop a methodology for computation of time reversal problems in commercial finite element software. The results prove that this method is extremely sensitive to the change of temperature and one have to pay special attention to tuning of elastic parameters relevant to the\nexperiment.
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Qualitative comparison of MEMS vibration sensors
Hasík, Stanislav ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The aim of this bachelor thesis is a qualitative parameter validation of MEMS vibration sensors using calibration devices from the companies SPECTRA a Brüel & Kjr. First part of study deals with different types of MEMS vibration sensors on the piezoresistive, capacitive and thermal principle of operation. The study also deals with primary and secondary methods of calibration of vibration sensors and devices used for these calibration methods. The second part of the thesis is to use the calibration chains and secondary calibration methods to verify the sensitivity and temperature dependences of three particular MEMS accelerometers from the companies STMicroelectronic, MEMSIC and Panasonic. The measured characteristics are compared with catalog datasheets. In the end of the thesis are also discussed the possibility of the suppression these temperature effects.
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