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Processing of electromagnetic and acoustic emission signals during mechanical stressing of solids
Šopík, Martin ; Holcman, Vladimír (referee) ; Koktavý, Pavel (advisor)
Electromagnetic emission and acoustic emission are physical phenomena evoked in non-conductive material by the sudden release of energy that generate rising cracks in material structure. The significant is a fact that these emission signals are detected already in stadium of materials loading whereof can be used e.g. at non-destructive diagnostics of building materials and constructions. In the appropriate manner processing of the emitted signals then make possible to obtain valuable informations for study physical properties of cracks. Master’s thesis describes methods designed for important signal data ascertainment in time, frequency even time-frequency domain. It can be e.g. start time, maximum value, dominant frequency in spectrum etc. All these methods are implemented into main program. Next load is formularization of source signal transformation which is given by used measuring circuit. Analytical method is chosen for solving. It means finding out reserve electrical circuit with constant element values. Resultant circuit approaches original circuit with less square error than existing way. The signal transformation is described by differential equation of second order with constant coefficients. MATLAB software is used for all computations and projections.
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Light Airplane Flight Parameters Estimation
Dittrich, Petr ; Pačes, Pavel (referee) ; Fiľakovský, Karol (referee) ; Chudý, Peter (advisor)
Tato práce je zaměřena na odhad letových parametrů malého letounu, konkrétně letounu Evektor SportStar RTC. Pro odhad letových parametrů jsou použity metody "Equation Error Method", "Output Error Method" a metody rekurzivních nejmenších čtverců. Práce je zaměřena na zkoumání charakteristik aerodynamických parametrů podélného pohybu a ověření, zda takto odhadnuté letové parametry odpovídají naměřeným datům a tudíž vytvářejí předpoklad pro realizaci dostatečně přesného modelu letadla. Odhadnuté letové parametry jsou dále porovnávány s a-priorními hodnotami získanými s využitím programů Tornado, AVL a softwarovéverze sbírky Datcom. Rozdíly mezi a-priorními hodnotami a odhadnutými letovými paramatery jsou porovnány s korekcemi publikovanými pro subsonické letové podmínky modelu letounu F-18 Hornet.
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Simulation of fluid flow around obstacles by Lattice Boltzmann Method
Prinz, František ; Pokorný, Jan (referee) ; Zatočilová, Jitka (advisor)
The task of this diploma thesis is the Lattice Boltzmann method (LBM). LBM is a mesoscopic method describing the particle motion in a fluid by the Boltzmann equation, where the distribution function is involved. The Chapman-Enskog expansion shows the connection with the macroscopic Navier-Stokes equations of conservation laws. In this process the Hermite polynoms are used. The Lattice Boltzmann equation is derived by the discretisation of velocity, space and time which is concluding to the numerical algorithm. This algorithm is applied at two problems of fluid flow: the two-dimensional square cavity and a flow arround obstacles. In both cases were the results of velocities compared to results calculated by finite volume method (FVM). The relative errors are in order of multiple 1 %.
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Aerodynamic Characteristics Identification of Atmospheric Airplane from Flight Measurement Results
Zikmund, Pavel ; Salga,, Jaroslav (referee) ; Jebáček, Ivo (referee) ; Daněk, Vladimír (advisor)
The thesis deals with aerodynamic characteristics identification from flight measurement. The topic is part of flight mechanic – handling qualities. The first theoretic part consists of three identification methods description: Error equation method, Output error method and Filter error method. Mathematical model of an airplane is defined and restricted to the motion with 3 degree of freedom. There is also introduced simulation of flight measurement for identification software validation. Practical part is focused on experiment preparation, execution and evaluation. The airplane VUT 700 Specto had been chosen to carry out flight tests. The airplane was modified to the new electric powered VUT 700e Specto after first measurement flights with combustion engine. Data record from on-board measurement unit was completed by telemetric data from autopilot and remote control system. Flight tests were carried out in stabilised mode of autopilot in symmetric flight. The results were confronted with analytical analysis results and DATCOM+ software parameter estimation.
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Aerodynamic Characteristics Identification of Atmospheric Airplane from Flight Measurement Results
Zikmund, Pavel ; Salga,, Jaroslav (referee) ; Jebáček, Ivo (referee) ; Daněk, Vladimír (advisor)
The thesis deals with aerodynamic characteristics identification from flight measurement. The topic is part of flight mechanic – handling qualities. The first theoretic part consists of three identification methods description: Error equation method, Output error method and Filter error method. Mathematical model of an airplane is defined and restricted to the motion with 3 degree of freedom. There is also introduced simulation of flight measurement for identification software validation. Practical part is focused on experiment preparation, execution and evaluation. The airplane VUT 700 Specto had been chosen to carry out flight tests. The airplane was modified to the new electric powered VUT 700e Specto after first measurement flights with combustion engine. Data record from on-board measurement unit was completed by telemetric data from autopilot and remote control system. Flight tests were carried out in stabilised mode of autopilot in symmetric flight. The results were confronted with analytical analysis results and DATCOM+ software parameter estimation.
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Acceleration of Neurostimulation Using Artificial Intelligence Methods
Gaňo, Martin ; Chlebík, Jakub (referee) ; Jaroš, Jiří (advisor)
Treatment using transcranial ultrasound is a rapidly arising domain of medicine. This method brings options for non-invasive brain therapies, including ablation, neuromodulation, or potentially opening the blood-brain barrier for the following treatment. The health officer needs to constantly receive feedback on the ultrasound wavefield in the human skull in real-time to accomplish the cure using these techniques. The traditional methods for simulating monochromous ultrasound waves are computationally too expensive. That is why their usage would be infeasible for these purposes, and it brings the need for alternative methods. This work proposed and implemented a method to solve the Helmholtz equation in 3D space using a neural network achieving a faster convergence rate. The neural network design uses lightweight architecture based on UNet. The main interest of this work is neuromodulation because, in this application, it is possible to ignore several variables and phenomena that would not be negligible in other use cases. Omitting them from the calculations increased the chances of accomplishing computations in a reasonable time. The method is fully unsupervised and uses exclusively artificially generated spherical harmonics and physics-based loss for training, with no required ground truth labels. Results showed a faster calculation with acceptable error than other traditional methods.
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Acceleration of Neurostimulation Using Artificial Intelligence Methods
Gaňo, Martin ; Chlebík, Jakub (referee) ; Jaroš, Jiří (advisor)
Treatment using transcranial ultrasound is a rapidly arising domain of medicine. This method brings options for non-invasive brain therapies, including ablation, neuromodulation, or potentially opening the blood-brain barrier for the following treatment. The health officer needs to constantly receive feedback on the ultrasound wavefield in the human skull in real-time to accomplish the cure using these techniques. The traditional methods for simulating monochromous ultrasound waves are computationally too expensive. That is why their usage would be infeasible for these purposes, and it brings the need for alternative methods. This work proposed and implemented a method to solve the Helmholtz equation in 3D space using a neural network achieving a faster convergence rate. The neural network design uses lightweight architecture based on UNet. The main interest of this work is neuromodulation because, in this application, it is possible to ignore several variables and phenomena that would not be negligible in other use cases. Omitting them from the calculations increased the chances of accomplishing computations in a reasonable time. The method is fully unsupervised and uses exclusively artificially generated spherical harmonics and physics-based loss for training, with no required ground truth labels. Results showed a faster calculation with acceptable error than other traditional methods.
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Mixed finite element method for the Poisson equation
Švihlová, Helena ; Knobloch, Petr (advisor) ; Dolejší, Vít (referee)
The aim of this bachelor thesis is the implementation of the mixed element method for the Poisson equation and the comparison with results of the classical finite element method. The thesis is divided into two chapters. In the first chapter there are descriptions of the spaces occurring in the weak formulation of the Poisson equation and descriptions of the spaces which are suitable to approach them. The second chapter studies the existence of the solutions of the approximated tasks and their convergence. The main part of this thesis are schemes of the solutions of both methods and the tables comparing errors of these solutions for three diferent functions. 1
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A posteriori error estimates for numerical solution of convection-difusion problems
Šebestová, Ivana ; Dolejší, Vít (advisor) ; Sváček, Petr (referee) ; Brandts, Jan (referee)
This thesis is concerned with several issues of a posteriori error estimates for linear problems. In its first part error estimates for the heat conduction equation discretized by the backward Euler method in time and discontinuous Galerkin method in space are derived. In the second part guaranteed and locally efficient error estimates involving algebraic error for Poisson equation discretized by the discontinuous Galerkin method are derived. The technique is based on the flux reconstruction where meshes with hanging nodes and variable polynomial degree are allowed. An adaptive strategy combining both adaptive mesh refinement and stopping criteria for iterative algebraic solvers is proposed. In the last part a numerical method for computing guaranteed lower and upper bounds of principal eigenvalues of symmetric linear elliptic differential operators is presented. 1
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Adaptivní volba parametrů stabilizačních metod pro rovnice konvekce-difúze
Lukáš, Petr ; Knobloch, Petr (advisor) ; Felcman, Jiří (referee)
Title: Adaptive choice of parameters in stabilization methods for convection- diffusion equations Author: Bc. Petr Lukáš (e-mail: luk.p@post.cz) Department: Department of Numerical Mathematics Supervisor: Doc. Mgr. Petr Knobloch, Dr. (e-mail: knobloch@karlin.mff.cuni.cz) Abstract: The aim of the work is to propose suitable approaches for adap- tive choice of parameters in stabilization methods for convection-difusion equations discretized by the finite element method. We introduce the L-SR1 method, compare it with other nonlinear methods of minimizing functions with large number of variables, and introduce and compare the adaptive methods based on minimizing of the error indicator. Keywords: Adaptive choice of parameters, finite element method, stabiliza- tion methods, convection-diffusion equation, L-SR1 method, error indicator
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