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Optimization of Basic Magnetic Field Homogeneity in MR Tomography
Hadinec, Michal ; Brančík, Lubomír (referee) ; Frollo, Ivan (referee) ; Bartušek, Karel (advisor)
This thesis is concerned with problems of measuring and mapping of magnetic field in MR tomograph, for purpose of magnetic flux density homogeneity optimization. Attention is paid to mapping techniques on rotary symmetric volume and to ways of magnetic fields optimization with utilization of passive and active correction systems. Theoretical analysis of magnetic field decomposition with utilization of spherical harmonics and numerical decomposition is made. Mapping and approximation techniques of basic magnetic field are verified by experiments in the laboratory at the Institute of Scientific Instruments AS CR in Brno.
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Modern statistical approach in evaluating the compressive strength of concrete in structures using the rebound hammer method
Janka, Marek ; Kocáb, Dalibor (referee) ; Misák, Petr (advisor)
This diploma thesis examines various linear regression methods and their use to establish regression relationships between the compressive strength of concrete determined by the indirect method and by the crushing of the specimens in the press. It deals mainly with the uncertainty of values measured by the indirect method, which is neglected by the usually used ordinary least squares regression method. It also deals with the weighted least squares method, suitable for so-called heteroskedastic data. It compares different regression methods on several sets of previously measured data. The final part of the work examines the effect of removing too influential points identified by Cook's distance, which may skew the regression results.
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Image composition
Smital, Petr ; Petyovský, Petr (referee) ; Richter, Miloslav (advisor)
This thesis deals with methods of improving the quality of image output of an electron microscope by composing consecutive frames. The thesis contains a brief description of an electron microscope and the problems that deteriorate its image quality, and three basic mathematical algorithms that can be used to remove them. These are the simple averaging method, the method of least squares and the method of vector space. For all of the methods, the thesis describes ways of their implementation, the possibilities of their use and their mutual comparison. This thesis also deals with the problem of so-called superresolution, i.e. exceeding the physical resolution of a sensor using the methods mentioned above, and the problem of electron beam centring.
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Control of Nonlinear Systems using Local Approximation Methods
Brablc, Martin ; Bugeja, Marvin (referee) ; Grepl, Robert (advisor)
Tato práce se zabývá návrhem adaptivního řídícího algortitmu pro konkrétní třídu elektromechanických aktuátorů, založeného na principu dopředného řízení pomocí inverzního dynamického modelu. Adaptibilita řízení spočívá v mechanismu získání inverzního dynamického modelu. Tato práce se zaměřuje na jeho online aproximaci pomocí lokálních aproximačních metod. Výstupem práce je shrnutí analýzy, simulačního testování a reálných experimentů, které testovaly možnosti praktického využití lokálných aproximačních metod pro účely adaptivního řízení v reálném prostředí.
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Least-Squares Method in System Identification
Matějka, Jiří ; Bělohradský, Petr (referee) ; Máša, Vítězslav (advisor)
This bachelor thesis deals with the description of the least squares method and its application in system identification of dynamic processes. It contains mathematical derivation of least squares method and basic principles of system identification. It describes parametrization of an mathematical model of experimental unit for biomass combustion.
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Identification of DC motor parameters
Kabelka, Ondřej ; Veselý, Libor (referee) ; Pohl, Lukáš (advisor)
This bachelor´s thesis deals with identification of parameters of the DC motor. An identification program in LabVIEW with data processing in Matlab has been created. After the identification of electrical and mechanical parameters of the motor there are current regulators and velocity regulators designed and implemented in the LabVIEW enviroment as a verification of the correctness of the identification.
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Hydraulic roughness of water supply pipes
Náplavová, Eva ; Hofmannová, Lenka (referee) ; Ručka, Jan (advisor)
This bachelor’s thesis deals with hydraulic roughness of water pipelines, its consideration while making a hydraulic model and subsequent calibration of hydraulic simulation model. In the theoretical part literary review about current approach to hydraulic modeling of water mains and its possible future direction is carried out, as well as an overview of used roughness coefficients, computational formulas and possible approaches to calibration of the hydraulic model. In the practical part of the thesis, a matematical model of the supply main of the water mains network of Hvozdná is compiled and is followed by its calibration. The method of weighted least squares is used as an objective function. Optimization methods are used to minimize the value of the objective function and thus to determine the hydraulic roughness of supply main.
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Least-squares fitting of multivariate data
Hrabec, Pavel ; Bednář, Josef (referee) ; Tomášek, Petr (advisor)
Thesis sumarizes basic theory required for inference of aproximation using the least squares method and aplicates this method on data obtained from engineering practice. Within thesis were created programs, in MATLAB enviroment, to solve this problem. MATLAB already contains several algorithms, wich are useful for solving this problem. Thesis includes comparsion of properties and test of those algorithms.
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Image analysis for correction of electron microscopes
Smital, Petr ; Schwarz, Daniel (referee) ; Kolář, Radim (advisor)
This thesis describes the physical nature of corrections of an electron microscope and mathematical methods of image processing required for their complete automation. The corrections include different types of focusing, astigmatism correction, electron beam centring, and image stabilisation. The mathematical methods described in this thesis include various methods of measuring focus and astigmatism, with and without using the Fourier transform, edge detection, histogram operations, and image registration, i.e. detection of spatial transformations in images. This thesis includes detailed descriptions of the mathematical methods, their evaluation using an “offline” application, descriptions of the algorithms of their implementation into an actual electron microscope and results of their testing on the actual electron microscope, in the form of a video footage grabbed from its control computer’s screen.
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