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Surface Wave Analysis and Inversion-Application to the Bohemian Massif
Kolínský, Petr ; Prokop Brokešová, Johana (advisor) ; Novotný, Oldřich (referee) ; Růžek, Bohuslav (referee)
title: Surface Wave Analysis and Inversion Application to the Bohemian Massif author: Mgr. Petr Kolínský, DiS. author's e-mail address: kolinsky@irsm.cas.cz departments: Department of Geophysics Faculty of Mathematics and Physics Charles University Prague V Holešovičkách 2, Praha 8 - 180 00, Czech Republic and Department of Seismology Institute of Rock Structure and Mechanics, v.v.i. Academy of Sciences of the Czech Republic V Holešovičkách 41, Praha 8 - 182 09, Czech Republic supervisor: RNDr. Johana Brokešová, CSc. supervisor's e-mail address: johana.brokesova@mff.cuni.cz consultant: RNDr. Jiří Málek, PhD. consultant's e-mail address: malek@irsm.cas.cz keywords: surface waves, group velocity, phase velocity, frequency-time analysis, multiple filtering, tomography, inversion problems, Earth crust structure, Bohemian Massif An overview of surface wave analysis methods as well as of inversion techniques is given. Special attention is paid to the multiple filtering method for dispersion curve estimation, which is described by two different ways in detail. The isometric method is used for dispersion curve inversion and its description and tests are presented. Described methods are further used in applications. The applications show examples of surface wave analysis and inversion for 1D and 2D...
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Modern Imaging Techniques in Medicine
Pařízek, Aleš ; Neuwirthová, Ludmila (referee) ; Rujbrová, Šárka (advisor)
Cílem této práce je popsat základní principy a fyzikální veličiny spjaté s jednotlivými zobrazovacími metodami a poté jednotlivé metody porovnat. Práce popisuje vznik rentgenového záření, jeho interakci s různými materiály a metody snímaní pro vytvoření obrazů. Dále se práce zabývá základním principem vytvoření 3D obrazů pomocí počítačové tomografie a jednotlivými generacemi tomografických strojů. V poslední části se práce věnuje principu nukleární magnetické resonance a základním parametrům pro vytvoření obrazů pomocí MRI systémů.
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RF coil for MR systém
Vojtíšek, Miloš ; Kořínek, Radim (referee) ; Gescheidtová, Eva (advisor)
The bachelor thesis is focused on radio frequency coils for magnetic resonance imaging systems. Magnetic resonance is used for imaging of many objects, especially human body in medicine, plants and many other different objects. For obtaining optimal results it is essential to use a special suitable coil for every single application. In the first part of this work, the short overview of principles of magnetic resonance imaging is described followed by a look at hardware used in MRI. The main aim of the work is design of several different types of RF coils used in MRI. Finally two suitable designs have been chosen for the purpose. Coils have been realized, tested in experiments. Results were analyzed, maps of generated magnetic field were calculated and homogeneity was determined.
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Measurement of conifers needles surface by MR tomography
Hladík, Roman ; Kubásek, Radek (referee) ; Mikulka, Jan (advisor)
This bachelor thesis deals with the tomography based on magnetic resonance and evaluation of scanned images of conifers needles. At first, it is described the physical basis and methods of magnetic resonance scanning of objects. Another part is devoted to graphical preprocessing, which consist of noise suppression and image segmentation. After that there are described the design and algorithm for parameter estimation implemented to the application. The first experimental measurements were lightly discussed and evaluated in the last part of the work. In the last part there are discussed results of the experimental measurement. The attached documents contain the source code in Matlab language.
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Analysis and segmentation of tomographic images
Dorazil, Jan ; Bartušek, Karel (referee) ; Smékal, Zdeněk (advisor)
The thesis deals with the edge detection in the magnetic resonance images and their segmentation. There are adduced the gradient based methods, methods based on zero-crossing in the Laplacian images and also methods combined both of the methods adduced above. These methods are compared to find the best one for the temporo-mandibular joint detection. Consequently sufficient segmentation method for particular parts of the temporo-mandibular joint (the condyle, the acetabulum and the articular disk) separation is chosen.
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Phase Coupling Between Core and Boundary Regions of a Thermal Plasma Jet
Hlína, Jan ; Šonský, Jiří
Time series of plasma jet radiation distributions in planes perpendicular to the jet axis were analyzed by the fast Fourier transform (FFT). Complex output yielded by FFT was used to study amplitudes and phase angles belonging to various frequencies occurring in the frequency spectra. The distributions of amplitudes and phase angles have shown the existence of characteristic core and boundary regions for various types of oscillations. Phase angle relations give evidence of coupling between the core and boundary of the jet at some frequencies.
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Nonlinear elastic wave spectroscopy in symbiosis with time reversal for localization of defects: TR-NEWS
Dos Santos, S. ; Vejvodová, Šárka ; Převorovský, Zdeněk
Using the symmetry invariance and reciprocity the classical NEWS methods are supplemented and improved by practically elaborated TR-NEWS procedure having the intrinsic property of enlarging frequency analysis bandwidth. Coded excitations have been generalized using Symmetry Analysis ESAM (Excitation Symmetry Analysis Method), including also the chirp-coded excitation, which improves the signal to noise ratio and enables harmonic imaging of complex specimen. In this paper, we propose a new NDT application of the above approaches implemented on a composite specimen with adhesive joints. The calibrated chirp-coded TR-NEWS imaging of the sample is obtained by using the symmetrical excitations, and pre- and post- signal processing. Localization of the scatterer is illustrated on 2D plot.
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