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Design of algorithms for a continuous steam quality measurement system
Hanák, Tomáš ; Tofel, Pavel (referee) ; Holcman, Vladimír (advisor)
This bachelor thesis deals with proposal of algorithm for continuous system of sterilizated steam. At the beginning we deal with the process of sterilization and its methods. Later on we talk over about the saturated steam and parameters of saturated steam. At the end of the bachelors thesis we discuss about current measurement of sterilization steam quality. Then, the procedure of simultaneous measurement of sterilization steam quality is described here. The last part is the evaluation of measured data and presentation of their results.
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Analysis of piezoelectric energy harvester for railway applications
Kubiš, Juraj ; Tofel, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This master´s thesis deals with a piezoelectric energy generator, witch is a device that converts mechanical stress into electrical energy. It is small device that is mostly placed on vibrating structures in order to collect energy. By gluing this piezoelectric layer to the bottom of the rail, it would be a suitable power supply for the communication modules, while obtaining a sufficient amount of energy. These modules ale used as self-powered sensors stations with vision to monitor the condition of railway lines in more detail. The problem of these modules is their power supply, when the energy gain from the generators located on the railway line is insufficient. By acquiring a new energy source, this problem can be greatly simplified and lead to simpler inspection and earlier maintenance on railway lines.
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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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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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Non-Linear Electro-Ultrasonic Spectroscopy of Resistive Materials
Tofel, Pavel ; Koktavý, Bohumil (referee) ; Smulko, Janusz (referee) ; Šikula, Josef (advisor)
Elektro-ultrazvuková spektroskopie je založena na interakci dvou signálů, elektrického střídavého signálu s frekvencí fE a ultrazvukového signálu s frekvencí fU. Ultrazvukový signál mění vzdálenost mezi vodivými zrny ve vzorku a tím mění jeho celkový elektrický odpor R. Změna odporu R je proměnná s frekvencí ultrazvukového signálu fU. Vzorek, který obsahuje mnoho defektů ve své struktuře, vykazuje vysokou změnu odporu R v porovnání se vzorkem bez defektů při stejné hodnotě ultrazvukového a elektrického signálu. V disertační práci je popsána elektro-ultrazvuková metoda na tlustovrstvých rezistorech, hořčíkových slitinách, monokrystalech Si a CdTe, varistorech a také jeden z prvních pokusů aplikace elektro-ultrazvukové spektroskopie na horninové vzorky a tak diagnostikovat jejich stav poškození. V našem případě byl proměřen vzorek žuly. Jelikož se jedná o nedestruktivní metodu testování, tak má tato metoda velmi perspektivní budoucnost. Tato metoda je citlivá na všechny defekty ve vzorku. Její výhodou je, že se měří velikost signálu ne frekvenci danou rozdílem nebo součtem budících frekvencí fE a fU a tím se dá dosáhnout vysoké citlivosti. V mém případě byl vždy měřen signál na rozdílové frekvenci fi = fE-fU.
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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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Signal analysis of transport and stochastic processes of emission detectors
Míšek, David ; Tofel, Pavel (referee) ; Andreev, Alexey (advisor)
This Diploma thesis deals with properties of CdTe detectors. This material is ranked among optical sensitive group. This thesis can be thematically divided into two basic parts. The first part describes properties of both elements and the chemical adduct. Selected properties show perfections of the material, which are specializing it to optical area of application. The end of this part contains description of contact metal-semiconductor. This problem is important to comprehension principle the material contact. In second part there were making many measurements. For more accurately compare were first measurements doing without light and then with light. During making measurement was changed wave length and temperature of sample. Key factors were Volt-Ampere characteristics and resistance result with changed temperature and wave length impact to the sample. For better accuracy measurements were done many times. All of data from measurement were cultivate by PC Easyplot programme.
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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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Principle of Argument Increment For Searching Polynomial Roots
Tošer, Pavel ; Tofel, Pavel (referee) ; Sadovský, Petr (advisor)
Several methods exist for searching multinominal roots. Methods in more cases are used only for special solves. The goal of this thesis is to discover solution for searching multinominal roots. The process is based on optimal iterative method in combination with priciple of argument increment. There is no procedure solving it in this way up to now. This method removes shortcomings already existing methods and she could also complement them with a new knowledge.
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