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Preparation and optimization of electrospun materials suitable as electricity generators
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This master's thesis is focused on energy harvesting and is divided into two parts: theoretical and practical part. The theoretical part of the thesis contains the dielectric parameters, the meaning of the piezoelectric and triboelectric effect and the principles of electric energy gain in energy havesting. The last chapter of the theoretical part is devoted to various electrospun materials suitable for energy harvesting. The practical part of the work deals with nanofibers as an energy generator and describes their dielectric parameters. In this part the relative permittivity and loss factor of selected types of nanofibers are measured. Also the triboelectric nanogenerator is made and it's properties are measured.
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Penile plethysmography
Koudelková, Zuzana ; Harabiš, Vratislav (referee) ; Hrozek, Jan (advisor)
This bachelor´s thesis focuses on methods that examine volumetric changes of genital organs (especially for volume changes in male sexual limb). These changes are used in the sex diagnosis. The most common type of examination is to determine sexual preference of the patient. The aim of this work is to describe how have been the changes investigated previously and how they are investigating in the routine practice now. Find out which are their limits. Try to build a new type of sensor which could help to better evaluate the volume changes. And try to create a program in LabVIEW environment in which the measured data is displayed and stored.
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Impact hammer calibration
Šafář, Jakub ; Havránek, Zdeněk (referee) ; Beneš, Petr (advisor)
The aim of this thesis is verification of sensitivity of an impact hammer ENDEVCO 2302-5. The tesis also discusses the possible negative influences of the experiment. Calibration of an impact hammer was performed using known mass.
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Development of PVDF nanofibers sensor
Klásek, Matyáš ; Tofel, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This diploma thesis deals with the feasibility of using PVDF nanofibers as an active sensor layer generating electrical signal. PVDF and related electromechanical effects are described. A research study is conducted regarding existing PVDF nanofiber applications and based on it, an event sensor design utilizing triboelectric effect and electrostatic induction is proposed. The electrical response of the layers is experimentally investigated and a pulse detection algorithm is conceived and implemented. Finally, a way of integrating the sensor into a rail track is proposed.
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Analysis of passive and semi-active damping of cantilever oscillation
Václavík, Tomáš ; Tofel, Pavel (referee) ; Hadaš, Zdeněk (advisor)
In this thesis passive and semi-active damping methods on a model of cantilever beam with piezoelectric patch are analyzed. Explanation of piezoelectric effect, classification of damping methods used for vibration control, description of their properties, their benefits and disadvantages, and lastly the challanges of their implementation is presented. Models of specified methods are carried out in MATLAB Simulink and the results are compared. Basic concept of electrical design of circuits for semi-active damping by SDDNC and SSD methods is introduced.
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Measurement system for determination of the piezoelectric charge coefficient
Kašpárek, Ondřej ; Skalský, Michal (referee) ; Fialka, Jiří (advisor)
The master's thesis deals with methods of measuring material coefficients of piezoelectric materials with a focus on direct methods of measuring piezoelectric charge constant. The first chapters of this paper focus on the theory of the piezoelectric effect, the description of piezoelectric material coefficients, and the theory of direct measurements of piezoelectric charge constant, where is the generated charge, which corresponds to the mechanical load, measured. The next part of this thesis deals with designing and creating advanced measuring systems based on the quasi-static method, which are measuring the electrical response of the material to a step-change in force or a harmonic force signal straining the testing sample. In the last part, the influences on the measurement results, such as the use of electromagnetic shielding, are investigated using the created measurement systems.
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Analytical model of composite cantilever with SMART layer
Dostal, Vojtěch ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
This bachelor's thesis deals with analytical modelling of composite cantilever with smart layer. The structure is based on the real piezoelectric generator, which is a solid cantilever beam with a layer of piezoelectric material attached to its bottom and top. The first part of this bachelor's thesis summarizes the knowledge of the energy harvesting, the process under which harvesting of electric energy from the piezoelectric generator belongs. Some piezoelectric materials are mentioned and described afterwards. At first, analytical modelling is implemented on the homogeneous cantilever beam. Then, the relations for required characteristics are derived for laminate structure, which is structurally similar to the piezoelectric generator. One chosen parameter will be changeable. Due to the ties of relations, the required characteristics will change as well, which are for the piezoelectric generator strain and deflection.
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Controller of three-axis nano-metric manipulator
Pernica, Lukáš ; Jedlička, Petr (referee) ; Drexler, Petr (advisor)
This diploma thesis describes the piezoelectric phenomenon and its use for positioning with nanometric precision in laboratory use. In the thesis is description of direct and indirect piezoelectric phenomenon, various types of piezoelectric actuators and ways of their control with the aim of eliminating their hysteresis. The goal is to design a controller for piezo actuator built in the three-axis nanometric manipulator Thorlabs MAX341/M.
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Electrical characterization of flexible nanofiber piezoelectric materials
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This bacherol thesis is focused on piezoelectric nanofibrous materials. The first part describes the formation, use and possible aplications of nanofibers. It further analyze the principle of piezoelectric effect. It is a conversion of mechanical energy into electric energy and conversely. The second part is focused on design of experimental workplace for measurement of functional material properties. The last section of the thesis is dedicated to the electrical characterization of PVDF nanofibers and to the measurement of the piezoelectric charge constant.
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