National Repository of Grey Literature 106 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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.
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.
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.
Measurement of weak magnetic field in 3D space
Bár, Martin ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
The aim of this thesis is to theoretically examine the magnetic field of miniature cylindrical NdFeB magnets, compare the simulation results to real-world measurements, and design a magnetic field probe using suitable sensors. A FEM simulation was conducted using Ansys AIM and FEMM 4.2. The simulation shows that the magnetic induction on the surface of the magnet depends on the diameter/height ratio. The simulation results also show that 21 µm thick protective layer of Ni-Cu-Ni metal on the surface of NdFeB magnets lowers flux density of the smallest magnet sample (1x1 mm) by up to 14 %. It was also concluded that a larger magnet edge radius results in a higher flux density on the surface of the magnet. The biggest differences between simulation data and data measured by the F.W. BELL gaussmeter occurred in the smallest magnet sample. Using the FEMM 4.2 simulation software, a three-axis magnetic field probe was designed. Potential problems with this probe design have been identified. A simple procedure for probe calibration was proposed.
Utilization of artificially created weak magnetic field for navigation in 3D space
Váňa, Dominik ; Beneš, Petr (referee) ; Havránek, Zdeněk (advisor)
This master's thesis focuses on the utilization of an artificially created weak magnetic field for navigation in 3D space. The theoretical part of this work deals with the general properties of the magnetic field and with its description. The next section of the theoretical part contains an overview of measuring principles for magnetic field measurements. Based on various types of measuring principles, the thesis elaborates on commercially available miniature sensors for magnetic field measurement with a measuring range up to 10 mT. The work focuses mainly on the magnetoresistive principle and fluxgate sensors. Furthermore, the theoretical part contains descriptions of methods for modeling the magnetic field of simple permanent magnets and various magnet assemblies. Lastly, the theoretical part involves a patent search of devices used for locating magnets that are installed in an intramedullary nail, which is used in intramedullary stabilization used on fractures of human bones. By locating the magnet in the nail, it is possible to precisely determine the position of the mounting holes. The practical part of the thesis deals with the analysis of magnetic field behavior in the vicinity of various magnetic assemblies, which were modeled in COMSOL Multiphysics using the finite element method. The models were created with the aim of analysing the behaviour of the magnetic field in the vicinity of the magnets and at the same time to find possible analytical functions that could be used to determine the position of the magnet in space relative to the probe. The result of this work is an analysis of various assemblies, which contains graphs of different dependencies and prescription of polynomial functions that approximate these dependencies. Another part of the thesis is the design of a probe that serves to locate the magnetic target. The work describes two possible methods of localization. For the differential method, a user interface in LabVIEW was created. The probe based on this method is fully capable of locating the magnet in the 2D plane. The state space search method is described only in theory.
Measurement of very small displacements with fiber-optic interferometer
Vybíral, Dominik ; Šedivá, Soňa (referee) ; Havránek, Zdeněk (advisor)
This master's thesis is focused on optical methods of measurement of very small dynamic displacements. Principles of interfermeters with picometer resolution including Fabry-Pérot interferometer are discussed and an integration using this interferometer was designed. Parasitic influencers of Fabry-Pérot interferometer were described as well as signal processing methods for interferometer's output signal. An interferometric meter for measurement of dynamic displacement was designed with frequency range of several kHz. These parameters are achieved under condition of photonic crystal layer placed on measured sample.
Fiber-optic sensor based on multi-mode interference
Hedl, Michal ; Havránek, Zdeněk (referee) ; Šedivá, Soňa (advisor)
This diploma thesis is focused on measurement of the physical quantities by fiber optic sensors based on multimode interference. The objective is to evaluate the appropriate method of signal provided by the spectrum analyzer. Firstly, a review of optics, optical phenomena and fibers is performed. The basic theory necessary for the realization of measurements and the principal of fiber optic sensors and SMS (singlemode–multimode–singlemode) structures are discussed. Finally, the automated measuring workplace for absorption spectrum measurement is created and described. Given data are finally evaluated by an artificial neural network and a sensor concept for practical utilization is designed.
Compact measurement system for calibration of vibration sensors
Šiket, Peter ; Beneš, Petr (referee) ; Havránek, Zdeněk (advisor)
Cieľom práce je návrh a vytvorenie kompaktného meracieho systému, ktorý bude slúžiť na sekundárnu kalibráciu vibračných senzorov. Na vývoj a implementáciu bol použitý hardware a software firmy National Instruments. Teoretická časť obsahuje informácie o technických požiadavkách pre kalibračný systém, ktoré vychádzajú z noriem ISO 16063-21. Ďalej zhŕňa teoretické a praktické detaily dizajnu známeho kalibračného systému firmy SPEKTRA Schwingungstechnik und Akustik GmbH Dresden, ktorý sa používa pre účely primárnej kalibrácie. Praktická časť sa zaoberá návrhom riadiaceho systému a grafického užívateľského rozhrania. Výsledky sekundárnej kalibrácie sú na koniec porovnané s výsledkami primárnej kalibrácie. Výsledkom práce je kompaktný merací systém na sekundárnu kalibráciu vibračných senzorov.
Bandlimited signals, their properties and extrapolation capabilities
Mihálik, Ondrej ; Havránek, Zdeněk (referee) ; Jura, Pavel (advisor)
The work is concerned with the band-limited signal extrapolation using truncated series of prolate spheroidal wave function. Our aim is to investigate the extent to which it is possible to extrapolate signal from its samples taken in a finite interval. It is often believed that this extrapolation method depends on computing definite integrals. We show an alternative approach by using the least squares method and we compare it with the methods of numerical integration. We also consider their performance in the presence of noise and the possibility of using these algorithms for real-time data processing. Finally all proposed algorithms are tested using real data from a microphone array, so that their performance can be compared.
Measurement of sound fields using non-contact optical methods
Karásek, David ; Skalský, Michal (referee) ; Havránek, Zdeněk (advisor)
The purpose of this paper is to assemble measurement chain dedicated to contactless measuring of acoustic fields emitted by test sources and to validate its results. At first author discusses possible optic methods which can be used to measure acoustic fields, then he talks about theoretical foundations which are needed to measure data and to reconstruct final data. The last two chapters are dedicated to cover basics about created program and to analyse various aspects which influence measured and reconstructed data. Created measurement chain is fully functional, at the end of this thesis are proposed some ways of improving

National Repository of Grey Literature : 106 records found   1 - 10nextend  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.