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Measurement of dynamic quality of gradient magnetic fields
Kabrda, Miroslav ; Kubásek, Radek (referee) ; Bartušek, Karel (advisor)
In the first chapter of bachelor thesis I focused on description the tomograph construction. The next chapter deals with the measurement of gradient magnetic fields, using methods based on instantaneous frequency. The thesis describes: the IF method, the IFSE method ( the method of measuring the instantaneous frequency of the spin echo), the IFSES method (the instantaneous frequency measurement method for a series of spins) and the method of Gradient decay measurement in NMR tomography. Each method describes the basic principles of the measurement, the excitation pulse sequence, obtainment of instantaneous frequency and the method of evaluation of the obtained signal. This bachelor thesis includes experimental measurements using the method of Gradient decay measurement in NMR tomography. The experimental data obtained are given and evaluated in the last chapter at the end of the thesis.
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Signal Decomposition using EMD transform
Mžourek, Zdeněk ; Mekyska, Jiří (referee) ; Smékal, Zdeněk (advisor)
Aim of this thesis is to introduce empiric mode decomposition as a method for decomposing arbitrarily nonlinear and non-stationary signal into intrinsic mode functions. Using empiric modal decomposition together with Hilbert transform produces instantaneous frequency. We can use this instatenous frequency to create a Hilbert spectrum and use it for analysis in time-frequency domain. In next part we show several drawbacks of this method. We also present several ways how to improve empirical mode decomposition algorithm to obtain better results. An example of decomposition by empiric mode decompositon is made to illustrate how the whole procedure works.
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Signal Decomposition using EMD transform
Mžourek, Zdeněk ; Mekyska, Jiří (referee) ; Smékal, Zdeněk (advisor)
Aim of this thesis is to introduce empiric mode decomposition as a method for decomposing arbitrarily nonlinear and non-stationary signal into intrinsic mode functions. Using empiric modal decomposition together with Hilbert transform produces instantaneous frequency. We can use this instatenous frequency to create a Hilbert spectrum and use it for analysis in time-frequency domain. In next part we show several drawbacks of this method. We also present several ways how to improve empirical mode decomposition algorithm to obtain better results. An example of decomposition by empiric mode decompositon is made to illustrate how the whole procedure works.
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Measurement of dynamic quality of gradient magnetic fields
Kabrda, Miroslav ; Kubásek, Radek (referee) ; Bartušek, Karel (advisor)
In the first chapter of bachelor thesis I focused on description the tomograph construction. The next chapter deals with the measurement of gradient magnetic fields, using methods based on instantaneous frequency. The thesis describes: the IF method, the IFSE method ( the method of measuring the instantaneous frequency of the spin echo), the IFSES method (the instantaneous frequency measurement method for a series of spins) and the method of Gradient decay measurement in NMR tomography. Each method describes the basic principles of the measurement, the excitation pulse sequence, obtainment of instantaneous frequency and the method of evaluation of the obtained signal. This bachelor thesis includes experimental measurements using the method of Gradient decay measurement in NMR tomography. The experimental data obtained are given and evaluated in the last chapter at the end of the thesis.
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