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Microposition control device
Kokeš, Ondřej ; Bajer, Arnošt (referee) ; Kadlec, Jaroslav (advisor)
Presented thesis analyses a function of the particular type of the nanopositioner with aim to suggest and construct an electronic device suitable for control of the nanopositioner slider. In presented material there is a description of the control signals and possibility of their generating in the respect of slider movement accuracy. The main goal of the thesis is to describe electronic units ranging from power supply, control processor unit part to end part that directly joint nanopositioner. There is also programme equipment for microcontroller and computer, communication description, movement measuring and calibration and draft for the close-up of the control loop for additional increase of the movement accuracy.
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Electrospinning of composite fiberous structures for piezoapplications
Schifferová, Zuzana ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
Polymer and composite polymer-ceramic nanofibers were prepared by electrospinning process. Solution of 20 wt.% polyvinylidene fluoride (PVDF) in a mixture of dimethyl sulfoxide (DMSO) and acetone in the ratio of 7:3 was chosen as the most suitable precursor. When preparing composite nanofibers, 20 wt.% of barium calcium zirconate titanate (BCZT) or barium titanate (BT) nanoparticles was added to this PVDF solution. Given parameters were defined as the most suitable for the process of electrospinning: voltage of 50 kV, feeding rate of 30 l/min, distance between emitter and collector of 20 cm and needle diameter of 17 G. The effect of polymer molecular weight and the rotation speed of collector was also studied. Various properties of prepared samples were studied: morphology and fiber diameter, phase composition with the use of x-ray diffraction and Fourier transform infrared spectroscopy and also chosen electrical properties. Lower fiber diameters appeared with lower polymer molecular weight and higher rotation speed of the collector. These parameters resulted in higher percentage of the piezoelectric phase as well. The smallest achieved fiber diameter was around 300 nm, the highest percentage of phase was 92 % and the highest piezoelectric constant had a value of 16 pC/N. Composite fibers filled with BT particles showed better properties that the ones filled with BCZT particles.
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Characterization of lead-free piezoelectric ceramics
Šťastná, Magdaléna ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This project is focused on lead-free piezoelectric ceramics which are meda in CEITEC. Behaviour of these ceramics is quite different from the lead one. The first part is dedicated to dielectrics and its polarisation techniques. These techniques also include the piezoelectric effect which occurs only in crystals without central symmetry. The following part is focused on piezoelectric materials, piezoelectric polymers and piezoelectric ceramics respectively. The next section of the project is dedicated to the design of an experimental workplace for direct measurement of the piezoelectric charge coefficient đť‘‘33. The experimental part of the work is focused on electric characterisation of lead-free piezoceramics.
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Nano-ammeter with galvanic isolation
Šimka, Marek ; Kubíček, Michal (referee) ; Kolka, Zdeněk (advisor)
This bachelor thesis deals with all the aspects, that are important in the designing of the nano-ammeter. In theoretical part, there are described possible ways to measure electrical current of very low values. Other parts of the thesis describe all parameters, which are influencing measurement accuracy. These are, for example, unwanted and leakage currents, but also other parasitic phenomena that may occur. Thesis explains how to minimize unwanted currents and other influences. Practical section provides more detailed description of the proposed main scheme. There are also described components, that have been selected as the main parts of the nano-ammeter circuit. Subsequent part contains analysis of printed circuit board including all layers. Furthermore, the thesis deals with the realization of equipment and possible errors. The results of the bachelor are summarized in the last chapter.
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Modelling and Verification of Piezoelectric Generator
Lán, Radek ; Singule, Vladislav (referee) ; Hadaš, Zdeněk (advisor)
This master's thesis deals with the development and verification of the model of the piezoelectric generator, incl. determination of its parameters. This mathematical model should be used as a tool for development of new devices, especially for analysis of applicability of available energy source (vibration) and for design of device itself. At first the review of energy harvesting is described deeply. Subsequently piezoelectric generators and the ways how we can model them, are depicted in details. The methodology of parameters estimation and model development is presented in state space or in MATLAB/Simulink environment and applied on the commercial generator Midé V21BL. A device has been made within the scope of the thesis, which can be used as an universal tool in experiments with generator. Finally the model is applied on the analysis of energy yield from man's walk and there is also brief introduction to model modifications.
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Flexible generators of electrical energy
Tesařová, Tereza ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This bachelor thesis is focused on actual research part of energy harvesting technologies – flexible electrical generators, which mean the special generating of electricity using specific flexible materials. The net charge result is affected by the incidental mechanism to transform certain energy form into electrical power and is influenced of material range, which determines what will be harnessed as a source of energy. The energy harvesting is aiming at producing alternative and efficient ways instead of harmful and strained manufacture processing.
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Design of testing device for piezocomposite sensors
Zlámal, Radim ; Chalupa, Jan (referee) ; Kšica, Filip (advisor)
Presented bachelor’s thesis describes the design and the following assembly of a device used for testing MFC sensors. In the first part, fundamental theoretical findings regarding main properties of the sensors are listed, including their description and comparison with other piezoelectric materials. Available methods for measuring a response from the sensor are mentioned sequentially by means of applied stress (tension/compression, bending, torsion). The second part focuses on realization of the device based on the chosen physical principle for loading the tested specimen, to which the sensor is firmly attached. Construction of the device is designed and adjusted to meet the input requirements and boundary conditions for bending. Both hardware and software are selected to simulate the specific form of mechanical loading. The last part involvesstatic measurements of deformations on the specimen using a charge amplifier, as well as modelling of various dynamic cycles sensed by utilizing a load resistor. Voltage signal from the sensor is converted to strain, which is further transformed into deflection for measurement verification, and finally, the functionality of the entire device is evaluated.
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Accurate controll of piezoactuator
Hurdálek, Tomáš ; Šifta,, Radim (referee) ; Urban, František (advisor)
This thesis deals with the possibility of current and voltage control of piezoactuators from the point of view of control of optical filters for retuning the optical spectrum. At first, there is an effort to clarify the basic physical principles that are closely related to this issue. The thesis also deals with different types of piezoactuators and determines which one is the most suitable for the application. Attention is also paid to the explanation of different control options. A comparison of available drivers was made. Measurements, circuit simulations and testing of various circuits of critical parts of the driver were made. Based on this, a current driver and a current source to power it were developed. The device has been constructed and tested.
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