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Measuring system for acoustic characterisation of materials
Plánka, Mikuláš ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The diploma thesis deals with the measurement of acoustic parameters of the material using the B\&K 4206 impedance tube, specifically the absorption and reflection coefficients. The theoretical part provides a basic overview of the measurement methodology and a description of measurement quantities related to acoustic materials characterization. The measurement procedure using the PULSE LabShop software is also described in this work. The main focus of this thesis is the design and implementation of a custom open measurement system created in LabVIEW used to determine the aforementioned materials parameters. The results of the measurements using the custom implementation and the PULSE LabShop software are compared and evaluated in this diploma thesis.
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Measurement system with preamplifier for calibration of vibration sensors
Kaštovský, Jan ; Doseděl, Martin (referee) ; Havránek, Zdeněk (advisor)
This thesis deals with the design and implementation of a preamplifier for vibration sensors with IEPE interface and also for vibration sensors with charge output. The thesis also deals with a modification of a computer application for a measuring system in LabVIEW. The thesis builds on the already implemented measuring system for secondary calibration of vibration sensors. The results of the secondary calibration of this system with the added preamplifier are compared with the results of a primary calibration.
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Analysis of liquid electrolyte electrical parameters using impedance spectroscopy
Brabenec, Josef ; Pikula, Stanislav (referee) ; Havránek, Zdeněk (advisor)
The bachelor thesis deals with impedance spectroscopy of electrochemical systems, especially liquid electrolytes. The method of impedance spectroscopy is widely used to describe electrochemical cells, batteries and electrolytes for diagnostic purposes over a wide range of frequencies. This thesis presents the main types of impedance imaging in the complex and frequency domain, as well as basic information on the measurement methods used and the methods for impedance analysis. The main part of the thesis was the development of software for automated impedance measurements and estimation of equivalent circuit parameters using basic and specialized circuit elements. A workplace with fabricated electrodes for liquid electrolyte measurements was prepared for the application. The functionality of the application was verified by real measurements of different concentrations of water and salt solutions. The validity of the estimated equivalent circuit parameters was verified on measured simple circuits connected from basic circuit elements and was also verified using the commercially used ZView software.
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Angle of arrival calculation methods for localization using UWB technology
Žaludek, Ivo ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
The thesis describes UWB technology, compares available hardware platforms and describes UWB localization methods. The practical part compares the methods of calculating the angle of arrival from the phase difference of signal arrival on the two-element antenna array. The calculation is performed using the analytically obtained arc sine function and also using the look-up table and the polynomial function. The content of the look-up table and the coefficients of the polynomial function are based on the measured characteristics of the UWB receiver (anchor). The best result was obtained using the look-up table. More accurate results were obtained when the phase difference of arrival values were averaged.
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Implementation and practical verification of methods for predictive identification of rolling bearings failures
Bár, Martin ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The aim of this thesis is to identify and classify rolling bearing failures. The first part of the thesis deals with the diagnosis of bearings using in-house measured data. Faults were introduced into two bearings. The first one was deformed and corroded. In the second bearing, the outer raceway was damaged. Vibration data was collected at regular intervals and processed in MATLAB. The values of the statistical features indicated faults in both bearings. Envelope analysis showed that both bearings had developed a fault on the outer raceway and a gradual fault on the cage. In the second part of this thesis, machine learning methods were used to classify defective bearings using the CWRU data set. The accelerometer data were divided into blocks in two ways. Vibration images were created from these blocks for convolutional neural networks (CNNs). The best prediction accuracy was achieved by 1D convolutional neural network (1DCNN) (99.2 %), followed by neural network (94.6 %) and SVM (94.4 %). Random Forest and SVM are the best methods when the training set is reduced, and among CNNs, MATLAB architecture and 1DCNN are the best. The most noise resistant method is Random Forest and neural network, and among CNNs, 1DCNN is the best. Methods using statistical features perform better than CNNs on extremely noisy data. Convolutional networks do not achieve good accuracy, which is probably due to the conversion of raw accelerometer data into vibration images.
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Comparison of Augustin and Thomas Aquinas philosophy and ethics
Havránek, Zdeněk ; Blažková, Miloslava (advisor) ; Hogenová, Anna (referee)
This Thesis deals with the philosophy and ethics of St.Thomas Aquinas and of St. Augustine. At first I characterize the time period then I am focusing on each cathegory concerning moral life of human being in the world such as God, soul, will, goodness, evil and happiness as well. My goal is to show the real purpose of human existence and to show how both philosophers understand individual topics, what is the same and different in their opinion.
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Acoustic fields visualization using laser interference
Raffay, Tobiáš ; Havránek, Zdeněk (referee) ; Skalský, Michal (advisor)
This bachelor thesis is focused on solving the visualization of acoustic waves using laser interference. The necessary theoretical knowledge to understand the used method of schlieren photography are summarized in the theoretical part. The practical part describes the implementation and results of the assembled systems, shows the differences, and solves the problems that occurred during testing. Apart from visualization of acoustic waves, we can also observe the flow of gases and air with small changes of refractive index.
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Diagnostic module for Single-Wire CAN bus
Jež, Michal ; Doseděl, Martin (referee) ; Havránek, Zdeněk (advisor)
The basic properties of the CAN bus are analyzed in the bachelor's thesis. Furthermore, this work deals with the availability of circuits for the implementation of the CAN bus and the physical layer Single Wire CAN. Subsequently, the design of the diagnostic unit for the CAN bus is processed. It also deals with the design of firmware for the diagnostic module and a PC program for subsequent data analysis. Finally, the compatibility of the Single Wire CAN bus with the Low Speed CAN bus is tested.
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Near-field acoustical holography methods in LabVIEW environment
Majvald, František ; Hnidka,, Jakub (referee) ; Havránek, Zdeněk (advisor)
Near-field acoustical holography is a standard method for sound source visualization and localization. In this thesis, commonly used and newly published near-field acoustic holography methods are introduced and analysed. In addition, regularization methods are presented together with finding options of optimal regularization parameter. Based on theory, a LabVIEW library is built containing four implemented near-field acoustical holography algorithms and two regularization methods. To verify the correctness of implementations, a testing application has been made. This application allows testing of implemented algorithms with simulated or experimentally measured data. The correctness of implementation is verified, and algorithms are compared to each other with respect to accuracy and speed of calculation.
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