This thesis is intended to provide fundamental information for the construction and analysis of rotordynamic theoretical models, and their comparison the experimental systems. Finite Element Method (FEM) is used to construct models using Timoshenko beam elements with viscous and hysteretic internal damping. Eigenvalues and eigenvectors of state space equations are used to perform stability analysis, produce critical speed maps, and visualize mode shapes. Frequency domain analysis of theoretical models is used to provide Bode diagrams and in experimental data full spectrum cascade plots. Experimental and theoretical model analyses are used to optimize the control algorithm for an Active Magnetic Bearing on an overhung rotor.

The master‘s thesis deals with optimization of continuum consisting of one or more different materials loaded statically or dynamically. The thesis aims on minimum compliance design and maximum eigen frequency design. For solution of each problem situation are written computational programmes in Python language itself and also as combination with commercial software ANSYS APDL.

This diploma thesis contains a summary of the general information about the torsion vibration of the crankshaft. The main task is to prepare a flexible model of the crankshaft in the FEM program ANSYS and the subsequent export into the MBS ADAMS / Engine. According to parameters the model of four-cylinder line tractor engine with flexible crankshaft is built. Crank mechanism is analyzed to determine the natural frequencies and natural modes. Finally the results are evaluated and compared with analytical calculations.

Die Arbeit beschäftigt sich mit der intuitiven Verwendung sprachlicher Elemente, welche hinsichtlich der im Kommunikationsprozess entstehenden Bedeutungen problematisch sein können. Hierfür wurde eine gefilmte Musikunterrichtsstunde analysiert. Es konnte festgestellt werden, dass die Lehrkraft durch eine unbewusste Verwendung des Begriffs “afrikanische Sachen” die Kategorien “afrikanisch” und “nicht-afrikanisch” etabliert. Diese werden von den Schüler*innen adaptiert und ihnen nach einer individuellen, subjektiven Selektion im Unterricht vorkommende Elemente untergeordnet, welche dann innerhalb einer hegemonialen Struktur positioniert werden, wobei ebenso Hierarchisierungsprozesse möglich sind. Ferner besteht die Möglichkeit, dass die Stilisierung kultureller Unterschiede seitens der Schüler*innen zur Folge hat, dass Kulturen an sich von ihnen als hermetische und unanfechtbare Einheiten wahrgenommen werden. In den Worten einer an der Musikunterrichtsstunde teilnehmenden Person: “afrikanisch singen [ist] anders.”

This work is describing basic methods of face recognition. The methods PCA, LDA, ICA, trace tranfsorm, elastic bunch graph map, genetic algorithm and neural network are described. In practical part, the PCA, PCA + RBF neural network and genetic algorithms are implemented. The RBF neural network is used in the way of clasificator and genetic algorithm is used for RBF NN training in one case and for selecting eigenvectors from PCA method in the other case. This method, PCA + GA, called EPCA, outperform other methods tested in this work on the ORL testing database.

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[pt] As informações sobre a sensibilidade da solução de um dado escoamento mediante a perturbações infinitesimais é importante para o seu completo entendimento. A análise de estabilidade de escoamentos pode ser utilizada na otimização de processos industriais. Na indústria de revestimento o controle da estabilidade é fundamental, uma vez que o escoamento na região de aplicação da camada de líquido sobre o substrato, de um modo geral, tem que ser laminar, bidimensional e em regime permanente. O objetive é determinar, dentro do espaço de parâmetros de operação, a região onde o escoamento é estável e conseqüêntemente a camada a ser revestida uniforme. Porém, por ser uma análise complexa, só é usada na indústria em estudos mais apurados. O sistema linear que descreve a estabilidade vai ser discretizado com o método de Galerkin / elementos finitos, dando origem a um problema de autovalor generalizado.Tanto para escoamentos com líquidos newtonianos como para escoamentos com líquidos viscoelásticos, uma das matrizes do problema de autovalor generalizado é singular e alguns autovalores se encontram no infinito. No escoamento com líquidos viscoelásticos parte do espectro é contínuo, aumentando o grau de dificuldade da análise numérica para encontrá-lo. Nesse trabalho, vamos apresentar um método baseado em transformações lineares tirando vantagem das estruturas matriciais e transformando-as em um problema de autovalor clássico com dimens são, pelo menos, três vezes menor que o original. O método elimina os autovalores infinitos do problema com um baixo custo computacional. A estabilidade de um escoamento de Couette unidimensional de líquido newtoniano é analisada como um primeiro exemplo. Depois, o início do estudo da estabilidade em um escoamento de Couette bidimensional e também um escoamento pistonado com o mesmo líquido. Generaliza-se o método para o escoamento de Couette de um líquido viscoelástico, os resultados para o escoamento de um líquido cujo comportamento mecânico é descrito pelo modelo de Maxwell são apresentados e comparados com a solução analítica de Gorodtsov & Leonov, 1967. A relação entre os autovetores do problema transformado e do original é apresentada. / [en] Steady state,two-dimensional flows may become unstable under two and three-dimensional disturbances, if the flow parameters exceed some critical values. In many practical situations, determining the parameters at which the flow becomes unstable is essential. The complete understanding of viscous and viscoelastic flows requires not only the steady state solution of the governing equations, but also its sensitivity to small perturbations. Linear stability analysis leads to a generalized eigenvalue problem, GEVP. Solving the GEVP is challenging, even for Newtonian liquids, because the incompressibility constraint creates singularities that lead to nonphysical eigenvalues at infinity. For viscoelastic flows, the difficulties are even higher because of the continuous spectrum of eigenmodes associated with differential constitutive equations. The complexity and high computational cost of solving the GEVP have probably discouraged the use of linear stability analysis of incompressible flows as a general engineering tool for design and optimization. The Couette flow of UCM liquids has been used as a classical problem to address some of the important issues related to stability analysis of viscoelastic flows. The spectrum consists of two discrete eigenvalues and a continuous segment of eigenvalues with real part equal to -1/We (We is the Weissenberg number). Most of the numerical approximation of the spectrum of viscoelastic Couette flow presented in the literature were obtained using spectral expansions. The eigenvalues close to the continuous part of the spectrum show very slow convergence. In this work, the linear stability of Couette flow of a Newtonian and UCM liquids were studied using finite element method, which makes it easier to extend the analysis to complex flows. A new procedure to eliminate the eigenvalues at infinity from the GEVP that come from differential equations is also proposed. The procedure takes advantage of the structure of the matrices involved and avoids the computational effort of common mapping techniques. With the proposed procedure, the GEVP is transformed into a smaller simple EVP, making the computations more effcient. Reducing the computational memory and time. The relation between the eigenvector from the original problem and the reduced one is also presented.

This thesis deals with the topic of assessing the design load-bearing capacity of a prestressed concrete railway bridge structure. The determination of the structure’s load-bearing capacity is carried out using probabilistic nonlinear analysis using the finite element method. Load-bearing capacity is determined for the recommended limit states. A fully probabilistic approach is compared to other reliability semi-probabilistic methods, such as the ECoV method according to Červenka and Eigen ECoV, and deterministic methods, like partial safety factor method, or the method according to ČSN EN 1992-2. The results are evaluated in terms of accuracy, consistency and time consumption for each method.