Esse trabalho está baseado na investigação dos detectores de falhas aplicando classificadores de classe única. As falhas a serem detectadas são relativas ao estado de funcionamento de cada componente do circuito, especificamente de suas tolerâncias (falha paramétrica). Usando a função de transferência de cada um dos circuitos são gerados e analisados os sinais de saída com os componentes dentro e fora da tolerância. Uma função degrau é aplicada à entrada do circuito, o sinal de saída desse circuito passa por uma função diferenciadora e um filtro. O sinal de saída do filtro passa por um processo de redução de atributos e finalmente, o sinal segue simultaneamente para os classificadores multiclasse e classe única. Na análise são empregados ferramentas de reconhecimento de padrões e de classificação de classe única. Os classficadores multiclasse são capazes de classificar o sinal de saída do circuito em uma das classes de falha para o qual foram treinados. Eles apresentam um bom desempenho quando as classes de falha não possuem superposição e quando eles não são apresentados a classes de falhas para os quais não foram treinados. Comitê de classificadores de classe única podem classificar o sinal de saída em uma ou mais classes de falha e também podem classificá-lo em nenhuma classe. Eles apresentam desempenho comparável ao classificador multiclasse, mas também são capazes detectar casos de sobreposição de classes de falhas e indicar situações de falhas para os quais não foram treinados (falhas desconhecidas). Os resultados obtidos nesse trabalho mostraram que os classificadores de classe única, além de ser compatível com o desempenho do classificador multiclasse quando não há sobreposição, também detectou todas as sobreposições existentes sugerindo as possíveis falhas. / This work deals with the application of one class classifiers in fault detection. The faults to be detected are related parametric faults. The transfer function of each circuit was generated and the outputs signals with the components in and out of tolerance were analyzed. Pattern recognition and one class classifications tools are employed to perform the analysis. The multiclass classifiers are able to classify the circuit output signal in one of the trained classes. They present a good performance when the fault classes do not overlap or when they are not presented to fault classes that were not presented in the training. The one class classifier committee may classify the output signal in one or more fault classes and may also classify them in none of the trained class faults. They present comparable performance to multiclass classifiers, but also are able to detect overlapping fault classes and show fault situations that were no present in the training (unknown faults).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work, it is developed a study of the transverse vibrations of a system composed by two parallel strings of equal length, coupled by a viscoelastic element. The frequencies and mode shapes are obtained using modal analysis and a block matrix formulation for the system. The mode shapes are written by the dynamic basis, composed by the solution of a second order problem with impulsive initial conditions, and its first derivative. In the undamped case, different cases of the problem are considered by varying the parameters of the strings. The orthogonality of the mode shapes and the impulse response matrix are used to solve the undamped forced case. In the damped case, it is considered again the matrix formulation and use dynamic basis, and we present an uncoupled problem from simplifications of the system parameters. The damped forced vibrations are studied using the adjoint modal method, from which there is an orthogonality between the mode shapes of the original system and the mode shapes of the adjoint system associated, allowing the uncoupling and solvability of the system. The forced response is determined by using the matrix fundamental response. / Neste trabalho é realizado um estudo sobre as vibrações transversais de um sistema formado por duas cordas paralelas, de mesmo comprimento, acopladas através de um elemento viscoelástico do tipo Winkler. As frequêencias e os modos de vibração são obtidos utilizando-se a análise modal e uma formulação matricial em blocos para o sistema. Os modos de vibração são escritos através da base dinâmica, composta pela solução de um problema de segunda ordem com condições iniciais impulsivas, e sua primeira derivada. No caso não amortecido são considerados diferentes casos para o problema, variando-se os parãmetros das cordas. A ortogonalidade dos modos e a resposta impulso matricial são usadas para resolver o caso forçado sem amortecimento. No caso amortecido, é apresentado um problema desacoplado a partir de simplificações nos parâmetros do sistema. As vibrações forçadas com amortecimento são estudadas usando-se o método modal adjunto, a partir do qual, existe uma ortogonalidade entre os modos de vibração do sistema original e os modos de vibração do sistema adjunto, possibilitando o desacoplamento e resolução do sistema. A resposta forçada é determinada usando a resposta fundamental matricial.

RESUMO No início de 1995 foi adotado no Brasil o Plano Real, tendo como um dos seus tripés de sustentação a busca pelo combate ao processo inflacionário crônico brasileiro que já se estendia por um longo período. Assim, a política monetária passou a ter um papel importante na determinação das variáveis macroeconômicas. Este trabalho busca analisar uma regra de política monetária que capte as variações ocorridas em todo o período do Plano Real, se estendendo até meados de 2005, bem como se deram as relações entre as variáveis econômicas neste período. A especificação proposta consiste na estimação de modelos não-lineares distintos dependendo do estado da economia (em crise ou fora de crise). Utilizamos um modelo com chaveamento Markoviano para a dinâmica da taxa de juros nominal onde a determinação de períodos de crise é feita por uma variável nãoobservada. Além disso, procuramos adotar dois algoritmos distintos de estimação, Expectation-Maximization (EM) e Monte Carlo Markov Chain (MCMC), concluindo que a análise para ambos é bastante próxima, sendo identificados os mesmos períodos entre regimes. Finalmente, motivamos a estimação através de modelos econômicos teóricos cujas dinâmicas são compatíveis com uma regra de fixação de juros não-linear, avaliando os padrões de resposta a impulso condicionados ao estado da economia (regimes de estabilidade e crise econômica). / ABSTRACT In the beginning of 1995, continuing the process of inflation combat, the monetary policy should have been an important role in the determinacy of macroeconomics variables. This work has a target analyzing a monetary rule that reflects the occurred variations in every Real Plan?s period. The specification proposed by the authors consists in an estimation of two independent nonlinear models for different states of the nature (crises or not crises). Here we estimate a model where the dynamic of the nominal interest rate follows a Markov Switching process and the regimes are unobservable variables. In addition, we try adopting two different algorithms to estimation; Expectation-Maximization (EM) and Monte Carlo Markov Chain (MCMC), concluded that the results are very similar. Finally, we motivate the estimations analyzing models where the theoretical dynamics of the economy are compatible with a nonlinear interest rate rule, analyzing the impulse response conditioned to state of economy (regimes of crises or not crises).

nÃo hà / Na Ãltima dÃcada, o mercado de crÃdito brasileiro experimentou um crescimento inÃdito na histÃria do paÃs, atingindo o nÃvel de 49% do Produto Interno Bruto. Tal fato està diretamente ligado ao desenvolvimento econÃmico do paÃs nos Ãltimos anos. Diante desse cenÃrio, o preÃo que se cobra nas operaÃÃes de crÃdito passou a ter importÃncia fundamental para a manutenÃÃo de um crescimento sustentÃvel. Nessa perspectiva, os spreads bancÃrios â diferenÃa entre a taxa de juros cobrada dos tomadores de crÃdito e o custo de captaÃÃo dos recursos depositados nas instituiÃÃes financeiras â passaram a ser questionados por conta do elevado nÃvel em que se encontram no Brasil. Esse trabalho se propÃe a analisar a evoluÃÃo do spread bancÃrio brasileiro na Ãltima dÃcada e investigar empiricamente seus determinantes. Para tanto, empregou-se nesta pesquisa a tÃcnica economÃtrica de Vetores Autoregressivos de modo a identificar e analisar as principais variÃveis que se relacionam com o spread no perÃodo de 2000 a 2012. AtravÃs da anÃlise das funÃÃes de Impulso e Resposta, o trabalho mostra que a inflaÃÃo à um dos principais determinantes macroeconÃmicos do spread no Brasil. / The unprecedented growth in the Brazilian credit market in recent years made it possible to reach an impressive level of its GDP. This fact is surely related to economic development experimented by the country in current years. Within this scenario, the price which is charged in credit operations started to play a fundamental role to the maintenance of sustainable growth. Thus, the bank spreads which mean the difference between the interest rate charged to borrowers and the funding cost of funds deposited at financial institutions â also began to be disputed in virtue of their actual high level state. The goal of this work is to evaluate the Brazilian banking spread sector evolution in the last decade and empirically investigate its determinants. Therefore, it may employ tools such as the so-called Vectors Autoregressive in order to figure out and work out the main variables which are related to spread regarding the 2000-2012 period. Making use of impulse-response functions, one intends to show that inflation is one of the main macroeconomic determinants to the Brazilian spread.

This study examines the dynamic relationship between changes in oil prices and the economic policy uncertainty index for a sample of both net oil-exporting and net oil-importing countries over the period 1997:01-2013:06. To achieve that, we extend the Diebold and Yilmaz (2009, 2012) dynamic spillover index using structural decomposition. The results reveal that economic policy uncertainty (oil price shocks) responds negatively to aggregate demand oil price shocks (economic policy uncertainty shocks). Furthermore, during the Great Recession of 2007-2009, total spillovers increase considerably, reaching unprecedented heights. Moreover, in net terms, economic policy uncertainty becomes the dominant transmitter of shocks between 1997 and 2009, while in the post-2009 period there is a significant role for supply-side and oil specific demand shocks, as net transmitters of spillover effects. These results are important for policy makers, as well as, investors interested in the oil market. (authors' abstract) / Series: Department of Economics Working Paper Series

This study examines the dynamic relationship between changes in oil prices and the economic policy uncertainty index for a sample of both net oil-exporting and net oil-importing countries over the period 1997:01-2013:06. To achieve that, an extension of the Diebold and Yilmaz (2009, 2012) dynamic spillover index based on structural decomposition is employed. The results reveal that economic policy uncertainty (oil price shocks) responds negatively to aggregate demand oil price shocks (economic policy uncertainty shocks). Furthermore, during the Great Recession of 2007-2009, total spillovers increase considerably, reaching unprecedented heights. Moreover, in net terms, economic policy uncertainty becomes the dominant transmitter of shocks between 1997 and 2009, while in the post-2009 period there is a significant role for supply-side and oil specific demand shocks, as net transmitters of spillover effects. These results are important for policy makers, as well as, investors interested in the oil market. (authors' abstract)

In this thesis the heterogeneity of regional real estate prices in United States is investigated. A high dimensional VAR model with additional exogenous predictors, originally introduced by \cite{fan11}, is adopted. In this framework, the common factor in regional house prices dynamics is explained by exogenous predictors and the spatial dependencies are captured by lagged house prices in other regions. For the purpose of estimation and variable selection under high-dimensional setting the concept of Penalized Least Squares (PLS) with different penalty functions (e.g. LASSO penalty) is studied in detail and implemented. Moreover, clustering methods are employed to identify subsets of statistical regions with similar house prices dynamics. It is demonstrated that these clusters are well geographically defined and contribute to a better interpretation of the VAR model. Next, we make use of the LASSO variable selection property in order to construct the impulse response functions and to simulate the prices behavior when a shock occurs. And last but not least, one-period-ahead forecasts from VAR model are compared to those from the Diffusion Index Factor Model by \cite{stock02}, a commonly used model for forecasts.

The aim of this paper is to analyse and compare inflation and its dynamics between two countries -- the Czech Republic and Germany -- applying a special kind of econometric models. The first part of this paper is dedicated to economic theory of inflation -- fundamental terms, measuring methods and its targeting. The monetary policy in the Czech Republic and Germany is also shortly introduced. Next chapter tries to describe the econometric concept which is used in this paper -- vector autoregression model (VAR model). In connection with the VAR models, Granger causality, impulse response function, cointegration and error correction model are mentioned as well. The empirical part includes application of selected models on real time series of macroeconomic indicators. Next to the interpretation of results, the forecasts are also implemented.

The aim of this diploma thesis is to empirically investigate the explanatory power of Austrian business cycle theory. My dataset consists of US quarterly time series within the period between 1971 and 2009. As regards the NBER classification, this dataset covers six complete business cycles, including the recent global financial crisis. Following Wainhouse (1984), Keeler (2001) and Bjerkenes et al. (2010) I use Granger causality as one of the primary tools of the analysis. Moreover I also add Impulse response functions to discover the direction of observed relationships. As regards my primary group of hypotheses I found significant empirical evidence for the connection between changes in interest rate and structure of production. The secondary group of hypotheses is less successful; however I found the very first empirical illustration of Garrison's version of ABCT.

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