|
|
Magnetic Energy Harvesting Device for Low Excitation Vibration
Szabó, Hugo ; Singule, Vladislav (referee) ; Rubeš, Ondřej (advisor)
This bachelor theasis is focused on a concept of a magnetic energy harvesting device for low exitation frequencies. The device is made out of mechanical and electrical part where mechanical part is made out of two levitating magnets that repent each other and an electrical part is made out of magnetic circuit and a coil whose relative motion induces voltage in the coil. Mathematical model is made in Matlab, Simulink and FEMM. Construction model is made in Inventor.
|
|
|
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.
|
|
|
Magnetic Energy Harvesting Device for Low Excitation Vibration
Szabó, Hugo ; Singule, Vladislav (referee) ; Rubeš, Ondřej (advisor)
This bachelor theasis is focused on a concept of a magnetic energy harvesting device for low exitation frequencies. The device is made out of mechanical and electrical part where mechanical part is made out of two levitating magnets that repent each other and an electrical part is made out of magnetic circuit and a coil whose relative motion induces voltage in the coil. Mathematical model is made in Matlab, Simulink and FEMM. Construction model is made in Inventor.
|
|
|
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.
|
|
|
Piezoceramics Measurements
Fialka, Jiří ; Fidler, Petr (referee) ; Beneš, Petr (advisor)
The master’s thesis deals with the piezoelectric coefficients, the resonance frequency and especially the piezoelectric constants verification. With the assistance of several devices, for instance LCR-meter HIOKI 3532, impedance analyzer Agilent 4294A and LCR-meter Agilent E4980A, the resonance and the anti-resonance frequencies as well as impedance and capacitance of samples are measured. The paper opens with the theory of the piezoelectric phenomenon and the difference between direct and indirect piezoelectric phenomenon, it also describes the basic behaviour of a piezoelectric ceramic element during mechanical straining or applied voltage. Further, the paper concerns the description of various piezoelectric constants and their calculations. Subsequent part of the paper is devoted to the temperature dependence of the main piezoelectric parameters of PZT ceramics. The materials coefficients are delineated as a function of temperature of the piezoelectric charge coefficients dij, relative permittivity r, electromechanical coupling factor kij and frequency constants Ni. One of the chapters also determines the piezoelectric charge constant d33 of PZT ceramics by laser interferometer and compares it with the value measured by resonance methods. The surface displacement was measured by a single-beam interferometer Polytec OFV-5000. The results of measurements of piezoelectric charge coefficients d33 acquired by the first and the second method are identical. The last section of the paper is focused on different methods of experimental studies on the characteristics of heat transfer by diffusing heat through conduction between the silver-plated surface of cylinder made of PZT ceramics. The effect on the resonance and the anti-resonance frequencies is monitored. There after, the real heat, determined by thermo camera and the physical model of heat transfer created in program COMSOL Multiphysics, is analysed.
|
|
|
Rezonanční frekvence generátorů syntetizovaných proudů
Kordík, Jozef ; Trávníček, Zdeněk ; Šafařík, P.
This contribution focuses on axisymmetric synthetic jet actuators from the theoretical point of view. In order to evaluate their resonance frequencies, four mathematical models were derived. The results were compared with experimental data, and analyzed. With respect to the theoretical and experimental results, the applicability and limits of the models were discussed. The results illustratively prove correctness of the previous derivation based on transformation of mechanical energy.
|
|
|
Frekvenční charakteristika generátoru anulárního syntetizovaného proudu s velkým vnitřním průměrem
Krejčí, A. Petr ; Trávníček, Zdeněk ; Tesař, Václav ; Kordík, Jozef ; Pavelka, Miroslav
An annular synthetic jet actuator of large inner/outer diameter ratio of the nozzle has been developed, and four variants were designed, manufactured, and tested. The resonance frequency was estimated theoretically, based on the mechanical energy balance, and then measured by the pneumometric method. The resultant value was found to be 40 Hz. The nozzle geometry effect on the resonance frequency and on the velocity was quantified; both effects were concluded to be surprisingly small, less than 5%.
|
guest ::
