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Measurement of Parameters of Piezoelectric Knock Sensors
Buchtík, Jaromír ; Málek, Petr (referee) ; Fialka, Jiří (advisor)
The first part of the bachelor thesis focuses on knock sensors. It deals with their use in industry on engines in biogas power plants, but also as part of internal combustion engines in vehicles. Furthermore, the work deals with the piezoelectric charge coefficient 33, as one of the main parameters to describe the piezoelectric element and the theory of its measurement methods. The second part of the work focuses on the measurement of individual elements. It begins with the measurement of simpler undamaged shapes, such as a disk or wafer. This was followed by the measurement of the ring-shaped element, which is the shape used in the sensor itself. Measurements were carried out both on bare rings and on screwed sensors or factory-sealed in plastic, from undamaged, to broken, chipped, cracked to loaded problems. The purpose of the work was to compare the measured data and find out whether it is possible to know whether the piezoceramic element in the sensor is damaged, or in what way
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Design of Non-Contact Temperature Measurement Method for Blast Furnace Lava
Mlejnek, David ; Šedivá, Soňa (referee) ; Fialka, Jiří (advisor)
The Bachelor Thesis focuses on theoretical design of the system for contactless measurement of temperature of lava flowing out of the blast furnace for the factory of the company Isover (Saint-Gobain) in Častolovice. The initial part of the Thesis contains the theoretical analysis on electromagnetic radiation, infrared light of electromagnetic spectrum and experimental temperature measurement using contactless meters. The subsequent parts of the Thesis focus on description of the blast furnace workplace where the theoretical design of the new contactless systém of temperature measurement shall take place, description of the current temperature measurement system, research of the contactless temperature sensor market and a design of the new systém of contactless measurement of lava temperature.
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Utilization of the plate waves in defectoscopy
Šály, Timotej ; Fialka, Jiří (referee) ; Beneš, Petr (advisor)
This master thesis explores the use of plate waves in defectoscopy, specifically in non-destructive testing of materials. It focuses on Lamb waves, ultrasonic waves that propagate efficiently through surfaces even over long distances with minimal energy loss. The thesis is divided into a theoretical part, where the methods of generation, detection and processing of plate waves are first analyzed and the ways of using Lamb waves in non-destructive testing are presented. In the practical part, a method to verify the dispersion curves by experimental measurements is described.
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Liquid flow measurement
Hradil, Jiří ; Fialka, Jiří (referee) ; Beneš, Petr (advisor)
In my master’s thesis, I consider with flow measurement. In shortness is described principle of flow sensors functionality, its advantages and disadvantages. I designed and made device for practice measurement of flow. On this device are installed three flowmeters The characteristic of this flowmeters were measured and evaluated. I made program in LabVIEW to collect and analyze information from instaled flowmeters.
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Ultrasonic Anemometer
Křepelka, Pavel ; Fialka, Jiří (referee) ; Beneš, Petr (advisor)
In the first section of this document, there are described principles of the wind measuring. Anemometers can be divides by physical principles to mechanical (propeller or cup), ultrasonic anemometers and thermoanemometers. This paper is focused to ultrasonic anemometers. In the next part, there are described principles of sound propagation in the atmosphere. There are studies of measurement theory and comparing of different approaches. Completed solutions are presented in patent exploration. Afterwards, there are introduction of market research. Important parameters of ultrasonic anemometers are highlighted. Main aim of work is designing prototype of ultrasonic anemometer. Software, hardware and construct of experimental anemometer were designed. Created anemometer was calibrated in aerodynamics tunnel and results were compared with simulation output.
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Measurement of the Magnetic Field
Šimberský, Michal ; Uher, Miroslav (referee) ; Fialka, Jiří (advisor)
This bachelor thesis deals with the measurement of the magnetic field and sensors, which can scan the magnetic field. In this work is explained the principle of Hall probes and three types of magnetic field sensors based on magnetoresistive principles namely AMR, GMR and TMR sensors. The thesis also deals with the generation of a homogeneous magnetic field with Helmholtz coils and design of such a coil.
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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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Workplace for automated conductivity measurement of liquids
Rajm, Martin ; Fialka, Jiří (referee) ; Havránek, Zdeněk (advisor)
Its aim the present Dissertation is to create a workplace for automated measurement of conductivity of liquids. Theoretical part describes principles and methods of measurement of conductivity of liquids and also measurement of temperatures of solutions. The reader is then made familiar with the program and development environment known as LabVIEW in which the measurement software has been created as well. This software serves also for the control of the LCR meter “HIOKI 3532-50” whose characteristic properties, control method and possibilities of measurement are briefly characterized in subsequent parts. The text includes also a mention about the GP-IB bus, thanks to which the LCR meter is able to communicate with PC. The actual liquid which is to be analyzed comes into contact, however, only with the four-electrode conductivity cell “WTW TetraCon 325” which is described in the Dissertation as well. The theoretical part is concluded with presentation of the multifunction card “NI USB-6008”, with the help of which the temperature of the solution analyzed is determined. In the practical part is description of the connection and explanation of the function of the measurement system as a whole. This is followed by a presentation of the actual measurement software intended for conductivity measurement. Both its structure, functions and some information about control are described there. This part of the Dissertation deals also with determination of the values of the elements of the conductivity probe replacement circuit and with the impact of measurement parameters on resulting measurement values.
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Measurement of the piezoelectric charge coefficient
Stehno, David ; Uher, Miroslav (referee) ; Fialka, Jiří (advisor)
The thesis aim was to study in theory the determination of piezoelectric coefficients, in particular piezoelectric coefficient of charge and to use different measurement methods to determine this factor. Also to further study the issue of determining the uncertainties and determine the measurement uncertainty. Measurements were conducted on cylinder-shaped samples, with different dimensions of individual samples. With type material PCM51 and PCM41. Piezoelectric coefficient measurements of charge was carried out using three methods: frequency, direct and quasi-static. The results achieved by all methods are compared at the end of this study and the measurements uncertainty are calculated and discussed for each method.
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Measurement of Parameters of Piezoelectric Active Elements for Acoustic Emission Sensors
Fialka, Jiří ; Erhart,, Jiří (referee) ; Sedlák, Petr (referee) ; Beneš, Petr (advisor)
The doctoral thesis discusses the measurement of parameters of piezoelectric (PZT) materials and the influence of temperature on their stability. In the introductory sections, the author briefly explains the piezoelectric effect and its use; simultaneously, methods for the preparation of piezoelectric materials and the measurement of their properties are presented to illustrate the analyzed problem. The experimental part of the thesis describes the procedure of measuring and calculating the complete matrix of material coefficients from samples of PZT ceramics. The applied set of piezoelectric samples complying with relevant European and world standards was made in the form of thin plates, thin discs and cylinders, via gradual modification of the large disc. The NCE51 and/or the older PCM51 ceramics obtained from the company Noliac Ceramics were used in determining the complete matrix and describing the measurement method. Both these types are soft piezoceramics composed from a solid solution of lead zirconate and lead titanate with the general chemical formula of Pb(Zr1-x,Tix)O3. The real crystallographic structure and chemical composition of the samples were confirmed by X-ray diffraction spectroscopy and energy dispersive spectroscopy (EDS), respectively. The frequency method was used for the measurement and calculation of all material coefficients. An Agilent 4294A impedance analyzer and a set of measuring tweezers marketed as “Tweezers Contact Test Fixture 16334A” were used in the process. Fast determination of the entire matrix of coefficients without any special requirement for the preparation of the samples to be measured was tested and verified. The charge coefficients of the piezoelectric material were confirmed by direct methods including the laser interferometer technique, the vibrometric method, and the procedure utilizing changes of the force applied to the sample. The advantages and disadvantages of the methods were compared and defined based on measurements and their results. The main part of thesis was focused on the behavior of piezoelectric material at high temperatures near the Curie point. Depolarization performed by means of a high temperature approaching the Curie point constitutes a significant yet hardly measurable material property of PZT ceramics. Commonly available vibrometric methods (d33-meters) do not appear to be suitable for the measurement of temperature dependencies, and for that reason the frequency technique was used. The piezoelectric charge coefficient, whose value can be effectively measured via the above-discussed frequency method, was selected as the indicator showing the depolarization state in the applied piezoelectric ceramics. The accuracy of the procedure was verified via comparison of the vibrometric method in cylinders of the NCE51 ceramics with different sizes, which are designed for the longitudinal length mode. The result is an optimized measurement methodology which facilitates accurate determination of the Curie temperature, namely phase transition to the cubic crystallographic structure. The experiment also proved the applicability of progressive, controlled depolarization of PZT ceramics via high temperature, and it also enabled us to define the temperature limits at which there occur irreversible changes of the piezoelectric properties of piezoceramics. In the measured NCE51 and PCM51 materials, the limit for the irreversible changes was equal to 95% of the Curie temperature.
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