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Bishop, Carlton Delos. "Finite impulse response filter design using cosine series functions." Doctoral diss., University of Central Florida, 1988. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/43377.
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University of Central Florida College of Engineering ThesisWindow functions have been extensively used for the design of SAW filters. The classical truncated cosine series functions, such as the Hamming and Blackmann functions, are only a few of an infinite set of such functions. The derivation of this set of functions from orthonormal basis sets and the criteria for obtaining the constant coefficients of the functions are presented. These functions are very useful because of the closed-form expressions and their easily recognizable Fourier transform. Another approach to the design of Gaussian shaped filters having a desired sidelobe level using a 40 term cosine series will be presented as well. This approach is again non-iterative and a near equi-ripple sidelobe level filter could be achieved. A deconvolution technique will also be presented. this has the advantage of being non-iterative, simple and fast. This design method produces results comparable to the Dolph-Chebyshev technique.
Ph.D.
Doctorate
Electrical Engineering and Communication
Engineering
Electrical Engineering
41 p.
vii, 41 leaves, bound : ill. ; 28 cm.
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Schulte, Walter B. "The frequency response, impulse response, and transfer function of an ocean waveguide /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSchulte.pdf.
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Thesis (M.S. in Applied Science (Signal Processing))--Naval Postgraduate School, June 2004.Thesis advisor(s): Lawrence J. Ziomek. Includes bibliographical references (p. 47). Also available online.
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Schulte, Walter B. III. "The frequency response, impulse response, and transfer function of an ocean waveguide." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1516.
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Approved for public release, distribution is unlimitedIn this thesis, the ocean was modeled as a waveguide with an ideal pressure - release surface, and an ideal rigid bottom. The ocean waveguide was then treated as a linear, time - invariant, space - variant (TISV) filter or communication channel. The filter is time - invariant because no motion was modeled and because the properties of the ocean were assumed to be constant. The filter is space - variant because of the presence of the two boundaries, that is, the ocean surface and ocean bottom. This thesis investigates the ocean as a linear TISV filter by evaluating 1) the complex frequency response, 2) the impulse response, and 3) the transfer function of the ocean with respect to depth. It is shown that the TISV impulse response of the ocean contains information that can be used to help localize a target in range and whether the target is above or below the receiver. Computer simulation results were obtained by evaluating the three filter functions for several different test cases.
Ensign, United States Navy
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Mitchell, James. "Identification and estimation of impulse response functions in VAR models : analysing monetary shocks in the G7 economies." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621674.
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Jonéus, Paulina. "The more the merrier? On the performance of factor-augmented models." Thesis, Uppsala universitet, Statistiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256760.
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Vector autoregression (VAR) models are widely used in an attempt to identify and measure the effect of monetary policy shocks on an economy and to forecast economic times series. However, the sparse information sets used in the VAR approach have been subject to criticism and in recent decades, the use of factor models as a means of dimension reduction has been a subject of greater focus. The method of summarizing information contained in a large set of macroeconomic time series by principal components, and use these as regressors in VAR models, has been pointed out as a potential solution to the problems of limited information and estimation of too many parameters. This paper combines the standard VAR methodology with dynamic factor analysis on Swedish data for two purposes, to assess the effects of monetary policy shocks and to examine the forecasting properties. Latent factors estimated by the principal components method are in this study found to contribute to a more coherent picture in line with economic theory, when examining monetary policy shocks to the Swedish economy. The factor-augmented models can on the other hand not be shown to increase the forecasting accuracy to a great extent compared to standard models.
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Pacifico, Antonio. "Heterogeneity, Commonality, and Interdependence in the Euro Area: Size and Dynamics of Fiscal Spillover Effects in Macroeconomic-Financial Linkages." Doctoral thesis, Luiss Guido Carli, 2014. http://hdl.handle.net/11393/287365.
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The paper develops empirical measures to estimate the strength and dymanic of fiscal spillover effects in the Euro Area. It moves for estimating a Bayesian VAR model of real and financial variables in order to examine in depth economic policy coordination and policy making, with a strong attention on the current financial crisis. Spillovers are estimated recursively with weakly-exogenous common factors. The aim of the project accounts for interdependencies across countries within the Euro Area and derives impulse response functions and conditional forecasts with the output of a Monte Carlo Marco Chain routine. However, the paper attempts to estimate the systemic contribution and cross-country transmission of unexpected shocks on the productivity in the Eurozone between June 1995 and March 2014. Overall, the positive impact on outputs in the financial dimension indicates the importance of coordinated fiscal actions among euro area members. Shocks overflow in a heterogeneous way across countries. Moreover, financial variables show higher amplification of spillover effects which can be seen as a result of increased interdependence between variables. Finally, the analysis is consistent and robust with the more recent literature on business cycles, which recognizes the importance of both group-specific and global factors in evaluating cross-country spillovers and responses to an unexpected shocks.
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Hathibelagal, Amithavikram Rugvedi. "The role of noise on rod signaling in the visual pathways." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122230/1/Amithavikram%20Rugvedi_Hathibelagal_Thesis.pdf.
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Rod and cone photoreceptors in the human eye operate simultaneously under dim (mesopic) illuminations, however, it's not clear how their signals interact to regulate our visual experience. These photoreceptor interactions were investigated using a new methodology designed to isolate rod-mediated vision by separating it from the effects of cone photoreceptor-specific noise. The outcomes revealed a mechanism requiring cone-directed transmission of rod signals through the primary visual pathways that optimizes human vision under twilight illumination.
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Zsitva, Norbert. "Aproximace LTI SISO systémů s dopravním zpožděním pomocí zobecněných Laguerrových funkcí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376971.
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This final thesis deals with the approximation of time delay in time invariant systems. First, the generalized Laguerre functions and their characteristics are presented. After this, the approximation of the Dirac delta function with the help of these functions is shown. Also, the choice of the free parameters is discussed and the results are evaluated with the help of energy. In the final part of the thesis, the approximations of systems with generalized and simple Laguerre functions are compared.
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Hidayat, Egi. "On Identification of Biological Systems." Doctoral thesis, Uppsala universitet, Avdelningen för systemteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-215699.
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System identification finds nowadays application in various areas of biological research as a tool of empiric mathematical modeling and model individualization. A fundamental challenge of system identification in biology awaits in the form of response variability. Furthermore, biological systems tend to exhibit high degree of nonlinearity as well as significant time delays. This thesis covers system identification approaches developed for the applications within two particular biomedical fields: neuroscience and endocrinology. The first topic of the thesis is parameter estimation of the classical Elementary Motion Detector (EMD) model in insect vision. There are two important aspects to be taken care of in the identification approach, namely the nonlinear dynamics of the individual EMD and the spatially distributed structure of multiple detectors producing a measurable neural response. Hence, the suggested identification method is comprised of two consecutive stages addressing each of the above aspects. Furthermore, visual stimulus design for high spatial excitation order has been investigated. The second topic is parameter estimation of mathematical model for testosterone regulation in the human male. The main challenges of this application are in the unavailability of input signal measurements and the presence of an unknown pulsatile feedback in the system resulting in a highly nonlinear closed-loop dynamics. Semi-blind identification method has been developed based on a recently proposed pulse-modulated model of pulsatile endocrine regulation. The two system identification problems treated in the thesis bear some resemblance in the sense that both involve measured signals that can be seen as square-integrable functions of time. This property is handled by transforming the signals into the Laguerre domain, i.e. by equivalently representing the functions with their infinite Laguerre series.
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Subramaniam, Vijayaratnam. "AGRICULTURAL INTERSECTORAL LINKAGES AND THEIR CONTRIBUTION TO ECONOMIC DEVELOPMENT." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/771.
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The transition from communism to capitalism at the end of the last century was one of the most significant events in the world economy since industrialization. During the latter part of the 1980s, people the Central and Eastern European countries and former Soviet Republics opted for a change from highly distorted command economic system to a market driven economic system. Privatization and liberalization policies led to major changes in the commodity mix and volume of agricultural production, consumption and trade. However, the changes and the impacts varied among countries as they followed different transition strategies.
This study investigated the impact of market liberalization on the agricultural sector, as well as how the inter-sectoral linkages among the agricultural, industrial and service sectors responded in Poland, Romania, Bulgaria and Hungary using time-series analysis. The study estimated an econometric model that incorporates the linkages among the sectors using a Vector Error Correction Model. The procedure identified long-run and short-run relationships for each country. The results showed that a sector can have a negative linkage to other sectors in the short-run; however, that does not mean that the linkage will be negative in the long-run.
Impulse response functions were constructed to determine how a system reacts to a shock in one of the endogenous variable in a model. The study explored how a shock in the agricultural sector was absorbed by the other sectors in the economy, and how a shock in the other sectors was absorbed by the agricultural sector, in all four countries. The responses reflected how the variables are interrelated within a country, and how the shocks are transferred through different linkages over a long period of time. Such dynamic analysis was used to identify the total impacts of different policy alternatives.
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Uzinski, Julio Cezar [UNESP]. "A state-space parameterization for perfect-reconstruction wavelet FIR filter banks with special orthonormal basis functions." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/146716.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Esta tese apresenta uma parametrização no espaço de estados para a transformada wavelet rápida. Esta parametrização é baseada em funções de base ortonormal e filtros de resposta finita ao impulso simultaneamente, uma vez que, a transformada rápida wavelet é um algoritmo que consiste em decompor sinais no domínio do tempo em sequências de coeficientes baseados numa base ortogonal de funções wavelet. Deste modo, vantagens apresentadas por ambas as propostas são incorporadas. Modelos de resposta finita ao impulso têm propriedades atrativas como vantagens computacionais e analíticas, garantia de estabilidade BIBO e robustez para a mudança de alguns parâmetros, dentre outras. Por outro lado, séries de funções de base ortonormal têm características que as fazem atrativas para a modelagem de sistemas dinâmicos, como ausência de recursão da saída, a não necessidade de se conhecer previamente a estrutura exata do vetor de regressão, possibilidade de aumentar a capacidade de representação do modelo aumentando-se o número de funções ortonormais utilizadas, desacoplamento natural das saídas em modelos multivariáveis; tolerância a dinâmicas não modeladas. Além disso, a realização no espaço de estados é mínima. A contribuição deste trabalho consiste no desenvolvimento de uma realização no espaço de estados para bancos de filtros wavelet, em que há a presença explícita de parâmetros que podem ser livremente ajustados mantendo as propriedades de reconstrução perfeita e ortonormalidade. Para ilustrar o funcionamento e as vantagens da técnica proposta, alguns exemplos de decomposição de sinais no contexto de processamento de sinais mostrando que ela proporciona os mesmos coeficientes wavelet que a transformada wavelet rápida, e uma aplicação em controle através de realimentação dinâmica de estados também são apresentados nesta tese.
This thesis presents a state-space parameterization for the fast wavelet transform. This parameterization is based on orthonormal basis functions and finite impulse response filters at the same time, since the fast wavelet transform is an algorithm, which converts a signal in the time domain into a sequence of coefficients based on an orthogonal basis of small finite wavelet functions. Advantages presented by both proposals are incorporated. Finite impulse response systems have attractive properties, for instance, computational and analytical advantages, BIBO stability and robustness guarantee to some parameter changes, and others. On the other hand, orthonormal basis functions have some characteristics that make them attractive for dynamic systems modeling, examples are, output recursion absence, not requiring prior regression vector exact structure knowledge; possibility of increasing the model representation capacity by increasing the number of orthonormal functions employed; natural outputs uncoupling in multivariable models; tolerance to unmodeled dynamics, and others. Furthermore, the state-space realization is minimal. The contribution of this work consists in the development of a state-space realization for a wavelet filter bank, with the explicit presence of the parameters that can be freely adjusted, keeping perfect-reconstruction and orthonormality guarantees. In order to illustrate advantages and how the proposed technique works, some decomposition examples in signal processing context are presented showing that it provides the same wavelet coefficients as the fast wavelet transform, and an application on dynamic state feedback control is also presented in this thesis.
CNPq: 160545/2013-7
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Uzinski, Julio Cezar. "A state-space parameterization for perfect-reconstruction wavelet FIR filter banks with special orthonormal basis functions /." Ilha Solteira, 2016. http://hdl.handle.net/11449/146716.
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Orientador: Francisco Villarreal AlvaradoResumo: Esta tese apresenta uma parametrização no espaço de estados para a transformada wavelet rápida. Esta parametrização é baseada em funções de base ortonormal e filtros de resposta finita ao impulso simultaneamente, uma vez que, a transformada rápida wavelet é um algoritmo que consiste em decompor sinais no domínio do tempo em sequências de coeficientes baseados numa base ortogonal de funções wavelet. Deste modo, vantagens apresentadas por ambas as propostas são incorporadas. Modelos de resposta finita ao impulso têm propriedades atrativas como vantagens computacionais e analíticas, garantia de estabilidade BIBO e robustez para a mudança de alguns parâmetros, dentre outras. Por outro lado, séries de funções de base ortonormal têm características que as fazem atrativas para a modelagem de sistemas dinâmicos, como ausência de recursão da saída, a não necessidade de se conhecer previamente a estrutura exata do vetor de regressão, possibilidade de aumentar a capacidade de representação do modelo aumentando-se o número de funções ortonormais utilizadas, desacoplamento natural das saídas em modelos multivariáveis; tolerância a dinâmicas não modeladas. Além disso, a realização no espaço de estados é mínima. A contribuição deste trabalho consiste no desenvolvimento de uma realização no espaço de estados para bancos de filtros wavelet, em que há a presença explícita de parâmetros que podem ser livremente ajustados mantendo as propriedades de reconstrução perfeita e ortonormalidade. ... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Maxa, Jan. "Analýha a komparace inflace v ČR a SRN." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-124610.
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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.
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Bisová, Sára. "Modely vývoje inflace a její volatility v ČR." Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-73484.
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This paper focuses on analysing and modelling inflation and its dynamics in Czech Republic applying a special kind of econometric models. Firstly economic theory of inflation is mentioned - fundamental terms, measuring methods of inflation, the way Czech national bank is monitoring the inflation and obviously a short summary of historical evolution of inflation in Czech economy. In the second part of this paper two econometric concepts of modelling time series are introduced - vector autoregression models (VAR models) and volatility models, concretely ARCH and GARCH models. In connection with the VAR models, Granger causality, impulse response functions, cointegration and error correction models are described. The empirical part includes application of selected models on real time series of chosen macroeconomic indicators. The estimation outputs are interpreted and forecasts are implemented. The quality of chosen econometric models for modelling inflation in Czech Republic is discussed.
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Scussel, Oscar. "Identificação não-paramétrica de sistemas mecânicos usando filtros de Kautz." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1066.
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Previous issue date: 2013-03-04Impulse Response Functions (IRFs) are important in many engineering applications, mainly in structural dynamics and modal analysis involving experimental modal tests. These IRFs can be identified through several methods. Among these, the classical covariance method is one of the most used and it is based on the sum of convolution from the correlation functions between input and output signals known. However, this method is limited because it employs a large number of samples and has drawbacks related to over parametrization. In this sense, this work presentes and review the covariance method expanded in the ortonormal basis Kautz functions, because this alternative way allows to avoid these drawbacks. In order to ilustrate the procedure an algorithm with multiple objective functions to obtain the optimal poles of the Kautz filter is shown. The results are provided through three degree-of-freedom mechanical system simulated and experimental data in a beam to show the advantages, drawbacks, simplicity and efficiency of the proposed approach.
As funções de resposta ao impulso (IRFs) exercem papel de destaque na identificação de sistemas reais quando têm-se o conhecimento dos dados de entrada/saída do sistema. Essas IRFs são relevantes em muitas aplicações de Engenharia, especialmente em análise modal experimental de estruturas. Dentre os métodos para obtenção dessas IRFs, destaca-se o clássico método das covariâncias baseado na soma de convolução das funções de correlação entre os sinais de entrada e saída conhecidos. No entanto, esse método é limitado quando são coletadas muitas amostras e possui algumas desvantagens como efeitos de sobreparametrização. Neste sentido, este trabalho apresenta e revisa o método das covariâncias expandido na base ortonormal de Kautz para aplicações em identificação de sistemas mecânicos, pois essa forma alternativa permite evitar esses efeitos de sobreparametrização. Para obter os pólos ótimos dos filtros de Kautz, emprega-se um algoritmo multi-objetivo. Os resultados são verificados através de um sistema mecânico com três graus de liberdade e em dados experimentais a partir de uma viga na condição livre-livre no qual verificam-se as vantagens, desvantagens, simplicidade e eficiência do método proposto.
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Ohnishi, Yusuke. "Temporal impulse response function of the visual system estimated from ocular following responses in humans." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225484.
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Janeiro, Eva Isabel Crisótomo. "Transmissão monetária: resultados da aplicação de modelos VAR a Portugal e Alemanha." Master's thesis, Instituto Superior de Economia e Gestão, 2004. http://hdl.handle.net/10400.5/2832.
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Mestrado em Economia Monetária e FinanceiraTendo em conta o enquadramento da Terceira Fase da UEM, este trabalho aborda a questão da transmissão da política monetária à economia real. São estimados modelos VAR que pretendem identificar os efeitos de choques de taxa de juro sobre o produto e preços de duas economias da UEM, Portugal e Alemanha, em dois contextos distintos, políticas monetárias independentes e política monetária única. Paralelamente, estuda-se a importância relativa dos vários canais de transmissão monetária para o efeito total registado (canais de taxa de juro, taxa de câmbio e crédito). Os resultados confirmaram, como seria esperado, a reacção negativa do produto e preços dos dois países a aumentos de taxa de juro. Na transmissão monetária do período pré-UEM foram encontradas diferenças entre os dois países, a nível da magnitude e do timingdos efeitos. Considerando os resultados no contexto de política monetária única, concluiu-se que parte dessas diferenças estaria associada às diferentes funções de reacção e não a diferenças nos mecanismos de transmissão. Adicionalmente, encontraram-se indícios de que o mecanismo de transmissão destes países não se tenha alterado, de forma significativa, a partir de 1999. Ainda no contexto da UEM, concluiu-se que Portugal ocupa uma posição vulnerável, como país pequeno e como detentor de um mecanismo de transmissão forte. Relativamente aos vários canais de transmissão, os resultados comprovaram a relevância do canal de taxa de câmbio para Portugal no período pré-UEM. O canal do crédito e o de taxa de juro foram considerados relevantes para este país em ambos os regimes de política monetária. Na Alemanha, a taxa de juro terá sido o principal canal de transmissão em funcionamento, tendo repartido parte do seu papel com o canal do crédito no contexto da UEM e, eventualmente, com o canal de taxa de câmbio no período pré-UEM.
This thesis examines the issue of monetary policy transmission against the background of Stage Three of EMU. The intention is to identify, through the estimation of VAR models, the effects of an interest rate shock on the output and prices of two EMU economies, Portugal and Germany. This is done from two different perspectives, monetary policy independence and common monetary policy. Concurrently it is studied the relative strength of different channels of monetary transmission (interest rate, exchange rate and credit). The results confirmed, as expected, that in both countries, an interest rate shock leads to a decrease in both output and prices. In the pre-EMU period, it was found some heterogeneity in monetary policy transmission of the two countries as regards the strength and timing of the effects. However, considering the outcome from the EMU perspective, it was concluded that part of this heterogeneity might be due to the different monetary policy reaction functions rather than different transmission mechanisms. Some results were also found that seem to point to the maintenance of transmission mechanisms, in these countries, after 1999. Under EMU, Portugal was seen as being in a vulnerable position, being a small country with a strong monetary transmission mechanism. As for the monetary transmission channels, the results confirmed the significance for Portugal of the exchange rate channel in the pre-EMU period. Credit and interest rate channels were found to be of relevance, for this country, in both monetary policy regimes. In Germany, the interest rate channel was the dominant factor in monetary policy transmission. However, part of it was shared with the credit channel within the EMU perspective and, possibly, with the exchange rate channel when considering the pre-EMU period.
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Komrska, Martin. "Rakouská teorie hospodářského cyklu: empirická evidence pro dlouhé období." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-150207.
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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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Wolff, Laion. "RELAÇÃO ENTRE AS DEZ PRINCIPAIS BOLSAS DE VALORES DO MUNDO E SUAS CO-INTEGRAÇÕES." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/8207.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorGlobalization provoked in financial markets by means stock exchanges an interchange among the markets over the world. The aim of this study was to examine the relationship of the ten major main economic index of the world represented in New York (DJIA, S&P500 e Nasdaq), Tokyo (NIKKEI 225), London (FSTE 100), São Paulo (IBOV), Shanghai (SSE180), Paris (CAC-40), Frankfurt (DAX-30) and Buenos Aires (Merval) and looking for its co-integration, to demonstrate the behavior of these indexes and the long run equilibrium, from January of 2010 to March of 2011. To investigate the equilibrium and the long rum behavior the error correction model was used jointly with co-integration test and impulse response based on Cholesky decomposition. The results of this study show that the index of stock markets has long term equilibrium, and American markets, Argentina and English showed a strong influence over other markets. With this research we can infer that a relationship exists between the stock markets under study, confirming that the economy in a country can influence the others. In this sense, the contribution of this study, given this range of discussions involving the interconnection of economies with respect to trades made on the stock exchanges, was to show the relationships and influences in the world.
A internacionalização somada à abertura dos mercados financeiros transformou as economias antes fechadas em economias abertas, provocou um intercâmbio entre as economias mundiais por meio das bolsas de valores. O objetivo deste estudo é examinar a relação entre os dez principais índices econômicos do mundo, sendo eles: Nova York (DJIA, S&P500 e Nasdaq), Tóquio (Nikkei 225), Londres (FSTE 100), São Paulo (IBOV), Shangai (SSE180), Paris (CAC), Frankfurt (DAX-30) e Bueno Aires (Merval), por meio da análise de co-integrações para demonstrar o comportamento desses índices e seus equilíbrios no período de janeiro de 2010 a março de 2011. Para investigar e verificar o comportamento em longo prazo, foi utilizado o modelo de correção de erros e teste de impulso-resposta baseado na decomposição de Cholesky. Os resultados deste estudo mostram que existe equilíbrio em longo prazo entre os índices do mercado de ações. Os mercados americano, argentino e inglês mostraram forte influência sobre os demais mercados. Com esta pesquisa, verifica-se que existe uma relação entre os mercados de ações estudados, confirmando que a economia de um país influencia as demais. A contribuição deste estudo é verificar a assertiva das discussões atuais sobre a dependência das economias mundiais com as negociações por meio da bolsa de valores.
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Venes, Nuno Miguel Simões. "Efeitos não keynesianos da política orçamental: evidência empírica para Portugal." Master's thesis, Instituto Superior de Economia e Gestão, 2003. http://hdl.handle.net/10400.5/2366.
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Mestrado em Economia Monetária e FinanceiraA questão dos efeitos macroeconómicos da política orçamental tem gerado uma controvérsia sem fim entre as escolas de pensamento económico. Se por um lado, os keynesianos defendem a ocorrência de efeitos positivos e persistentes resultantes de políticas de carácter mais expansionista, os defensores da chamada «perspectiva alemã» advogam precisamente o contrário. De acordo com a visão não-keynesiana, uma política de consolidação gera efeitos expansionistas, assim como uma política dita expansionista provoca, em geral, contracções no PIB e na despesa privada. Este trabalho surge assim no contexto deste intenso debate de ópticas opostas. E elaborado um estudo empírico para a economia portuguesa a partir do qual se pretendem apurar os efeitos de uma variação do consumo público. A partir da estimação de um modelo VAR se mi-estrutural com cinco variáveis endógenas (nas quais se incluem o consumo público real e o PIB real) para um conjunto de observações trimestrais entre 1982 e 2000, é identificado um vector de choques estruturais sobre o consumo público real e simulados os seus efeitos dinâmicos sobre as restantes variáveis do modelo, em particular o PIB real, impondo a restrição de que o consumo público não é contemporaneamente afectado por choques nas restantes variáveis. No final, comparam-se as conclusões com os resultados obtidos nos principais trabalhos de investigação sobre esta matéria.
The discussion about the macroeconomic effects of fiscal policy has been generating a never-ending controversy among the schools of economic thought If on the one hand, Keynesians stand up for the occurrence of posilive and permanent effects arising from policies with a more expansionary nature, on the other hand, defenders of the so-called "German view» defend precisely the opposite. According to the non-keynesian point of view, consolidation produces expansionary effects, whereas an expansionary policy gives rise, in general, to GDP and private expenditure contractions. This work then arises in the context of this deep debate of opposite points of view. We develop an empirical study of the Portuguese economy from which we attempt to investigate the effects of a one-time shock on total public consumption. From the estimation of a semi-structural VAR model with five endogenous variables (including real public consumption and real GDP) to a set of quarterly data from 1982 to 2000, we identify a vector of structural shocks on real public consumption and simulate their dynamic effects on the remaining variables of the model, particularly real GDP, imposing the restriction that the public consumption is not contemporaneously affected by changes in the remaining variables. At the end. we compare our conclusions with the results obtained in related papers.
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Archibald, Charles Mark. "Experimental determination of the impulse response function for elastic vibrating systems." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41049.
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An experimental method for determination and analysis of the impulse response function of linear, elastic, vibrating systems is developed. A deconvolution method is developed for estimation of the impulse response function. The estimator is shown to be unbiased in the presence of measurement noise. Modal parameters are extracted from impulse response estimates using a modification of the Pisarenko harmonic decomposition method. The advantages of a time-domain approach over traditional Fourier analysis procedures, including avoidance of leakage and enhanced statistical significance, are described. Several tests used to determine the performance of the impulse response estimator are described, and the results of these tests, are presented. It is shown that the method can provide accurate estimates of modal parameters even for short data sets or high noise levels.
Master of Science
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Mozayyan, Sina. "Statistisk undersökning av valutakurser : En jämförelse mellan olika prognosmodeller." Thesis, Stockholms universitet, Statistiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-152182.
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Valutamarknaden är världens största marknad och en nödvändig del av dagens globala samhälle, som gör det möjligt för företag att göra affärer i olika valutor och mellan olika gränser. Marknaden utgör en stor handelsplattform för både små och stora aktörer, för vilka det är viktigt att prognostisera valutakurser med gott resultat. Att modellera finansiella instrument i form av tidsserier är en av de vanligaste investeringsstrategierna och dess användningsområde sträcker sig från valutamarknaden till bland annat aktiemarknaden och råvarumarknaden. I denna uppsats undersöks fyra olika statistiska metoder för att modellera valutakursen Euro-US Dollar givet historisk data, och prognoser görs med de framtagna modellerna. Dessa metoder är slumpvandring, ARIMA, ARIMA-GARCH och VAR. Vidare undersöks för den dynamiska VAR-modellen hur valutamarkanden påverkar, och blir påverkad av, långa och korta räntan. Resultaten visar att ARIMA(3,1,2) förklarar valutakursen bäst medan VAR(2) med valutakursen och skillnaden mellan långa räntor som ingående variabler ger de bästa prediktionerna.The foreign exchange market is the world’s largest market and is an essential part of the global society of today. The FX market enables companies to trade with different currencies across country borders. It is also a large trade-platform for both big and small financial actors, who greatly benefit from the advantages of good predictions. Modeling of financial instruments is one of the most commonly used investment strategies and its area of application ranges from the FX market to markets suchas the stock market and the commodity market. In this paper, four different statistical models are used to model the currency pair Euro-US Dollar. These methods are random walk, ARIMA, ARIMA-GARCH and VAR. Besides investigating which method that gives the best forecasts, the method that best describes the training datais also found. Furthermore, for the dynamic VAR model, it is explored how the FX market affects, and is affected by, the long term and short term interest. The results show that ARIMA(3,1,2) is the best at describing the exchange rate while VAR(2) with the exchange rate and the difference between long term interests as variables gives the best predictions.
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Dahlin, Alexander. "The Price Dynamics of Regional Family Houses in Sweden : Ripple Effect or Not?" Thesis, KTH, Fastigheter och byggande, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254836.
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This paper builds on the study Prices on the Second-hand Market for Swedish Family Housesconducted by Lennart Berg, economist and associate professor emeritus from UppsalaUniversity in 2002. This study attempts to identify inter-and intraregional pricedependencies in Sweden for the second hand market for family houses. The house priceindices used in this econometric analysis commences in 1990:1 and ends in 2018:4 for allregions in accordance to NUTS 2 in Sweden.This thesis models the change of the regional prices for one-and two family houses indicatingthat the metropolitan area of Stockholm contributes predominantly to all other regionsthroughout the country. In addition, the capital city also shows cointegrated relationshipswith all regions although not the contrary. Shocks to the housing market of Stockholmindicate that Gothenburg, the Western region and Malmö are affected contemporaneouslyfollowed by the other regions nationwide with a certain time lag leading to say that thecontribution and influence of the capital city´s house price development leads the pricedevelopment throughout the country, Sweden.Detta examensarbete ligger till grund av den tidigare studien Prices on the Second-handMarket for Swedish Family Houses av Lennart Berg, nationalekonom och professor emerituspå Uppsala Universitet, 2002. Denna studie har som mål att finna de inter-och intraregionala pris förhållanden i Sverige på den inhemska andrahandsmarknaden för en-och tvåfamiljhus. Med hjälp av ekonometriska analyser har fastighetsprisindex använts i rapportenmellan år 1990:1 till 2018:4 för samtliga regioner i landet enligt indelning av NUTS 2.Denna uppsats skattar de regionala prisförändringar för en-och två familjehus därindikationer tyder på att Stockholms län verkar vara prisledande i relation till alla andraregioner och storstadsområden i Sverige. Därutöver, visar det sig att huvudstaden harkointegrerande samband med resten av landets regioner dock ej tvärtom. Simuleradeekonomiska chocker på Stockholms län visar att att Stor-Göteborg, Västsverige och Stor-Malmö är påverkade samtidigt med hänsyn till tid följd av de resterande regionerna med ettvisst lag. Detta kan tyda på att Stockholms regionala utveckling samt prispåverkan lederprisutvecklingen i landet.
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Filho, JoÃo Francisco de Souza. "Causalidade entre as taxas de crescimento dos paÃses desenvolvidos e emergentes." Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2424.
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AtravÃs da utilizaÃÃo de instrumentais estatÃsticos e economÃtricos para a anÃlise de sÃries temporais, buscou-se verificar as relaÃÃes entre as taxas de crescimento dos
paÃses desenvolvidos e emergentes. Para tanto, utilizou-se de uma amostra contendo a taxa real de crescimento econÃmico desses paÃses no perÃodo de 1970-2007. Com base nesse estudo, verificou-se que existe causalidade, no sentido
Granger, do crescimento econÃmico dos paÃses desenvolvidos em direÃÃo aos paÃses emergentes. A funÃÃo de resposta a impulsos mostrou que a resposta dos paÃses emergentes a choques no crescimento dos paÃses desenvolvidos foi a mais significativa e duradoura.Through the use of statistical and econometric instrumentals for the analysis of time series, this work aims to verify the relationships between the economic growth rate of developed and emergent countries. For so much, it was used of a sample containing the real economic growth rate of those countries in the period of 1970-2007. With base in this study, it was verified that causality exists, in the sense of Granger, of the economic growth rate of the countries developed towards the emerging countries. The impulse response function showed that the answer of the emerging countries to impacts in the economic growth of the developed countries was the most significant and durable.
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Bronselaer, Benjamin, Michael Winton, Joellen Russell, Christopher L. Sabine, and Samar Khatiwala. "Agreement of CMIP5 Simulated and Observed Ocean Anthropogenic CO2 Uptake." AMER GEOPHYSICAL UNION, 2017. http://hdl.handle.net/10150/626555.
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Previous studies found large biases between individual observational and model estimates of historical ocean anthropogenic carbon uptake. We show that the largest bias between the Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble mean and between two observational estimates of ocean anthropogenic carbon is due to a difference in start date. After adjusting the CMIP5 and observational estimates to the 1791-1995 period, all three carbon uptake estimates agree to within 3Pg of C, about 4% of the total. The CMIP5 ensemble mean spatial bias compared to the observations is generally smaller than the observational error, apart from a negative bias in the Southern Ocean and a positive bias in the Southern Indian and Pacific Oceans compensating each other in the global mean. This dipole pattern is likely due to an equatorward and weak bias in the position of Southern Hemisphere westerlies and lack of mode and intermediate water ventilation.
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Homeili, Saeid. "Metrological characterisation of Low Power Voltage Transformers by using impulse response analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20998/.
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this thesis presents a new approach in dealing with characterize LPVT and proposes determining the impulse response of LPVT, purposing to find transfer function (h(t)) which contains most electrical characteristics of LPVTs as a dynamic system.
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Vasquez-Ruiz, Harold A. "A New Approach to Estimate the Incidence of the Corporate Income Tax." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/econ_diss/82.
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After Harberger published his influential paper in 1962, many authors have assessed empirically whether the incidence of the corporate income tax (CIT) falls on capital owners, consumers, or workers (Krzyzaniak and Musgrave, 1963; Gordon, 1967; Arulampalam et al., 2008). Today, there is little agreement among economists about who bears the incidence of the CIT (Gruber, 2007; Harberger, 2008a,b). The reason for the little convincing evidence is that the econometric models used in the literature ignore that the factors that motivate changes in corporate tax policy are sometimes correlated with other developments in the economy and disentangling those effects from exogenous policy changes requires tremendous effort.
Using annual information at the industry level for the United States, I propose to investigate the consequences of exogenous changes in corporate tax policy. The identification of these exogenous events follows the work of Romer and Romer (2009, 2010), who provide an extensive analysis of the U.S. federal tax legislation using narrative records from presidential speeches and congressional reports, among other documentations.
The results validate the original predictions from Harberger (1995, 2008a). That is, in the short-term, capital owners bear the full burden of the tax. Over time, however, capital owners are able to shift this burden either by raising consumers' goods prices, or decreasing workers' wages. The magnitude of these e ects depends on the degree of capital intensity as well as the access to international markets and the availability of substitutes for the industry under consideration.
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Barros, Francisco JuscÃlio de. "The volatility of the exchange rate affects the Cearà exports?" Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11473.
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The aim of this work is understand how the Exchange rate volatility affects the cearensesâs exports. Many researchers have appointed that an increase in the exchange rate volatility generate risk factors on trade. Therefore, understand the relationship between volatility and trade is fundamental to forecast better the behavior of trade under instabilities of the exchange markets, as the recent international crisis. The period of analysis is from 2002 to 2011 and the data has monthly frequency. Two methodologies are used to investigate this relationship: short run, through impulse response function, obtained from a VEC; long run, through the Johansen cointegration test. The results showed that the exchange volatility reduces the exports of CearÃ.O objetivo deste trabalho à entender como a volatilidade da taxa de cÃmbio afeta as exportaÃÃes cearenses. Diversos autores tÃm apontado que uma volatilidade da taxa de cÃmbio mais elevada pode estar associada a fatores de risco de exportaÃÃo e importaÃÃo. Dessa forma, entender o relacionamento entre esses componentes à fundamental para aumentar o poder de previsibilidade, especialmente, em perÃodos de instabilidade econÃmica, em que a volatilidade da taxa de cÃmbio tende a ser maior. Nesse trabalho, utilizou-se de dados com frequÃncia mensal entre 2002 a 2012. Duas anÃlises foram feitas: uma de curto prazo, atravÃs da abordagem de funÃÃes impulso resposta obtidas a partir de um VEC e outra de longo prazo atravÃs do teste de cointegraÃÃo de Johansen (1991). Dos resultados encontrados, verificou-se que a volatilidade da taxa de cÃmbio tem efeito sobre as exportaÃÃes cearenses tanto no curto quanto no longo prazo. Ambos, longo e curto prazo, a volatilidade da taxa de cambio reduz o quantum exportado, indicando que tal volatilidade pode ser interpretada como risco associado as exportaÃÃes.
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Kim, Max, and Adham Belbaisi. "Correction of Radial Sampling Trajectories by Modeling Nominal Gradient Waveforms and Convolving with Gradient Impulse Response Function." Thesis, KTH, Medicinteknik och hälsosystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254347.
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There are several reasons for using non-Cartesian k-space sampling methods in Magnetic Resonance Imaging (MRI). Such a method is radial sampling, which includes the advantage of continuous coverage of the k-space center which results in higher robustness to motion. On the other hand, radial imaging does have some limitations that must be considered. The method is more sensitive to gradient imperfections, such as eddy currents and gradient delays, resulting in inconsistencies between the nominal and actual gradient waveforms. This leads to distortions in the sampling trajectory, also called trajectory errors, yielding reconstructed images with artifacts caused by the gradient imperfections. The aim of this project was therefore to implement a method that takes these errors into account and perform a correction of the trajectory errors to yield images with reduced artifacts. Various methods have been proposed for correction of the gradient errors, some more effective than others. The method implemented in this project was based on the gradient impulse response function (GIRF) which characterizes the gradient system responses. When GIRF was acquired, the actual gradient waveforms played-out during the imaging measurement could be predicted by first modeling the nominal gradient waveforms and then performing a convolution with the corresponding GIRF for each gradient axis. The imaging experiments involved measurements on two different resolution phantoms and in-vivo measurements to note possible differences in correction performance. The used pulse sequences for imaging were FLASH and bSSFP. The results showed that the applied method using GIRF did reduce the artifacts caused by gradient imperfections in the reconstructed images taken with the FLASH sequence. On the other hand, the results for the bSSFP sequence were not as successful due to incomplete modeling of the gradient waveforms. The conclusion to be drawn is that the GIRF-correction does adequately compensate for the trajectory errors when using a radial sampling trajectory for the FLASH sequence and hence yield images with almost eliminated artifacts. A suggestion for future work would be to further investigate the bSSFP sequence modeling to obtain better bSSFP-images.Det finns flera anledningar till att använda icke-Kartesiska k-space samplingsmetoder i magnetisk resonanstomografi. En sådan metod är radiell sampling, som har fördelen att kontinuerligt samla in mätdata från mittpunkten av k-space, vilket resulterar i lägre rörelsekänslighet under bildtagningstillfället. Radiell sampling har dock begränsningar som måste tas i beaktande, som gradient imperfektioner och gradientfördröjningar. Dessa leder till förvrängningar i samplingspositioneringen i k-space, även känt som trajektoriefel, vilket ger upphov till artefakter vid bildrekonstruktion. Syftet med projektet är att korrigera för dessa trajektoriefel så att den rekonstruerade bilden innehåller färre artefakter. Olika metoder har föreslagits för korrektion av gradientfel. Metoden som användes i detta projekt baseras på gradient impulsresponsfunktionen (GIRF), som karaktäriserar gradient systemet. För att estimera de verkliga samplingspositionerna i k-space beräknades de förvrängda gradientvågformerna efter varje mätning. Detta gjordes genom att först modellera de nominella gradientvågformerna och därefter utföra en faltning med GIRF. De utförda experimenten under projektets gång bestod av bildtagning av två fantomer och ett antal in-vivo mätningar för att identifiera eventuella skillnader i de rekonstruerade bilderna. Pulssekvenserna som användes under projektet var FLASH och bSSFP. Resultaten visade att GIRF-korrektionen reducerade artefakter orsakade av gradient imperfektioner i de rekonstruerade bilderna tagna med FLASH-sekvensen. Erhållna resultat med bSSFP-sekvensen var å andra sidan inte lika lyckade på grund av inkomplett modellering av gradientvågformerna. Slutsatsen som kan dras är att GIRF-korrektionen kompenserar för trajektoriefel i radiell sampling för FLASH-sekvensen och ger rekonstruerade bilder där artefakterna nästan eliminerats. Ett förslag för framtida arbeten är att vidare undersöka modelleringen av bSSFP-sekvensen för att erhålla bättre bilder.
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DELLA, NOCE MATTEO. "Un modello VAR-GARCH multivariato per il mercato elettrico italiano." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/1108.
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E’ stato estesamente appurato che i mercati dell'elettricità mostrano mean-reversion e elevata volatilità dei prezzi. Questo lavoro utilizza un modello VAR-MGARCH al fine di cogliere queste caratteristiche presenti sul mercato dell'energia elettrica italiana (IPEX) e analizzare le interrelazioni esistenti tra le diverse regioni in cui il mercato è suddiviso. L’analisi è condotta sui prezzi giornalieri dal 1 ° gennaio 2006 al 31 dicembre 2008.
I coefficienti stimati dalle equazioni condizionali indicano che i mercati regionali sono abbastanza integrati e i prezzi regionali dell'energia elettrica possono essere adeguatamente previsti impiegando i prezzi passati di ciascun mercato zonale.
La volatilità e la cross-volatility sono significative per tutti i mercati, indicando la presenza di forti componenti ARCH e GARCH e la sostanziale inefficienza dei mercati. E’ inoltre evidente un’elevata persistenza della volatilità e della cross-volatility in tutti i mercati.
I risultati indicano inoltre che gli shock rilevati, sia nella volatilità, sia nei vari mercati, persistono nel tempo e che in ogni mercato la persistenza è più marcata quando è causata da innovazioni stimate sulle stesso mercato rispetto a shock stimati su altre aree. Questa persistenza descrive la tendenza delle variazioni dei prezzi a raggrupparsi nel tempo.It is commonly known that spot electricity markets show mean-reversion and high price volatility. This work employs a VAR-MGARCH model to capture these features in the Italian electricity market (IPEX) and analyze the interrelation existing among the different regions in which the market is divided. Daily spot prices from 1 January 2006 to 31 December 2008 are employed. The estimated coefficients from the conditional mean equations indicate that the regional markets are quite integrated and regional electricity prices could be usefully forecasted using lagged prices from either the same market or from the other areal markets. Volatility and cross-volatility spill-overs are significant for all markets, indicating the presence of strong ARCH and GARCH effects and market inefficiency. Strong persistence of volatility and cross-volatility are also evident in all local markets. The results also indicate that volatility innovations or shocks in all markets persist over time and that in every market this persistence is more marked for own-innovations or shocks than cross-innovations or shocks. This persistence captures the propensity of price changes of similar magnitude to cluster in time.
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DELLA, NOCE MATTEO. "Un modello VAR-GARCH multivariato per il mercato elettrico italiano." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/1108.
Full textAbstract:
E’ stato estesamente appurato che i mercati dell'elettricità mostrano mean-reversion e elevata volatilità dei prezzi. Questo lavoro utilizza un modello VAR-MGARCH al fine di cogliere queste caratteristiche presenti sul mercato dell'energia elettrica italiana (IPEX) e analizzare le interrelazioni esistenti tra le diverse regioni in cui il mercato è suddiviso. L’analisi è condotta sui prezzi giornalieri dal 1 ° gennaio 2006 al 31 dicembre 2008.
I coefficienti stimati dalle equazioni condizionali indicano che i mercati regionali sono abbastanza integrati e i prezzi regionali dell'energia elettrica possono essere adeguatamente previsti impiegando i prezzi passati di ciascun mercato zonale.
La volatilità e la cross-volatility sono significative per tutti i mercati, indicando la presenza di forti componenti ARCH e GARCH e la sostanziale inefficienza dei mercati. E’ inoltre evidente un’elevata persistenza della volatilità e della cross-volatility in tutti i mercati.
I risultati indicano inoltre che gli shock rilevati, sia nella volatilità, sia nei vari mercati, persistono nel tempo e che in ogni mercato la persistenza è più marcata quando è causata da innovazioni stimate sulle stesso mercato rispetto a shock stimati su altre aree. Questa persistenza descrive la tendenza delle variazioni dei prezzi a raggrupparsi nel tempo.It is commonly known that spot electricity markets show mean-reversion and high price volatility. This work employs a VAR-MGARCH model to capture these features in the Italian electricity market (IPEX) and analyze the interrelation existing among the different regions in which the market is divided. Daily spot prices from 1 January 2006 to 31 December 2008 are employed. The estimated coefficients from the conditional mean equations indicate that the regional markets are quite integrated and regional electricity prices could be usefully forecasted using lagged prices from either the same market or from the other areal markets. Volatility and cross-volatility spill-overs are significant for all markets, indicating the presence of strong ARCH and GARCH effects and market inefficiency. Strong persistence of volatility and cross-volatility are also evident in all local markets. The results also indicate that volatility innovations or shocks in all markets persist over time and that in every market this persistence is more marked for own-innovations or shocks than cross-innovations or shocks. This persistence captures the propensity of price changes of similar magnitude to cluster in time.
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Carvalho, RanÃrio Noronha de. "A evoluÃÃo do Spread bancÃrio brasileiro na Ãltima dÃcada: uma investigaÃÃo empÃrica dos seus determinantes." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14353.
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nÃo hÃNa 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.
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Borén, Christofer, and Felix Ewert. "Assessing the Effect of the Riksbank Repo Rate on National Output and Price Level in Sweden : Focusing on Employment and Housing Prices." Thesis, KTH, Matematisk statistik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228969.
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There is no single commonly adapted model that explains the influence that various monetary policy instruments carry for the economy. During 2011-2017, the Swedish inflation rate has remained below the 2 percent target which has led the Riksbank to take measures aimed at stimulating the inflation. As of May 2018, the repo rate has experienced a number of decreases and is now at 0:50% which represents an unprecedentedly low level. With the inflation rate remaining below the target whilst the housing market has experienced substantial growth and recent decline, the question arises regarding what impact the repo rate exerts on various macroeconomic measures. In this paper, a statistical time series analysis is conducted using a Vector Autoregression model and the impulse responses are studied. A model of 7 economic variables is constructed to specially study the effect of the repo rate on employment and housing prices. Results demonstrate that rational expectations exist in the economy. Furthermore, results show that the repo rate influences factors affected by inflation rapidly, exerting maximum influence during the first year after the shock. On the other hand, real variables based on quantitative measures that are adjusted for inflation experience the greatest influence of the repo rate after a delay of 6 to 7 quarters. Employment experiences the greatest negative response to a repo rate shock after 7 quarters, with a magnitude of 0.317 standard deviations per standard deviation in the repo rate shock. Housing prices experience the greatest negative response to a repo rate shock after 4 quarters, with a magnitude of 0.209 standard deviations per standard deviation in the repo rate shock.Det finns ingen allmänt vedertagen modell som beskriver olika penningpolitiska instruments påverkan på ekonomin. Under 2011-2017 har Sveriges inflationstakt legat under 2-procentsmålet vilket har fått Riksbanken att vidta åtgärder i syfte att stimulera inflationen. Fram till maj 2018 har upprepade sänkningar av reporäntan genomförts och den ligger i dagsläget på 0:50% vilket är den lägsta nivån någonsin. Då inflationstakten inte nått målet samtidigt som bostadsmarknaden har upplevt kraftig tillväxt och nylig nedgång uppstår frågan gällande vilken effekt som reporäntan utlovar på diverse makroekonomiska mått. I denna rapport genomförs en statistisk tidsserieanalys med en vektorautoregression och impuls-responserna studeras. En modell med 7 ekonomiska variabler skapas för att specifikt studera effekten av reporäntan på sysselsättning och bostadspriser. Resultaten visar att rationella förväntningar finns i ekonomin. Vidare visar resultaten att reporäntan influerar inflationspåverkade variabler omgående, med maximal påverkan inom det första året efter chocken. Å andra sidan påverkas volymbaserade variabler som justeras för inflation maximalt först efter en fördröjning på 6 till 7 kvartal. Sysselsättningen upplever störst negativ påverkan från en reporäntechock efter 7 kvartal motsvarande 0.317 standardavvikelser per standardavvikelse i chocken. Bostadspriser upplever störst negativ påverkan från en reporäntechock efter 4 kvartal motsvarande 0.209 standardavvikelser per standardavvikelse i chocken.
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Lopes, João Daniel Barosa. "A relação entre a procura interna e a produção em Portugal : uma análise com recurso ao modelo vetorial autorregressivo." Master's thesis, Instituto Superior de Economia e Gestão, 2020. http://hdl.handle.net/10400.5/20732.
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Mestrado em Econometria Aplicada e PrevisãoA Procura Interna representa um papel essencial na economia como motor de crescimento do nível de produção de bens e serviços de qualquer país. Para Portugal, dada a forte dimensão do Consumo Privado, essa influência na produção é ainda mais notória. Dessa forma, para melhor descrever a economia nacional é fundamental estabelecer as relações inter-dinâmicas entre Consumo, Investimento e PIB, para que os agentes económicos sejam capazes de antecipar mudanças e dessa forma ajustar as suas decisões. Como tal, com recurso a dados trimestrais compreendidos entre o 1º trimestre de 1999 e o 4º trimestre de 2018, o presente estudo procedeu à estimação de um modelo Vetorial Autorregressivo (VAR) que permitiu identificar o forte impacto das duas componentes da Procura Interna na Produção de bens e serviços e um efeito não tão marcado no sentido inverso. Para além disso, através dos resultados obtidos pelo do modelo VAR estimado foi ainda possível identificar que face a um choque exógeno em qualquer uma das variáveis do sistema, as respostas das outras variáveis aparentam não se prolongar por períodos superiores a um ano. Contudo, apesar do forte poder explicativo, do ponto de vista das previsões a abordagem com recurso ao modelo vetorial não se revelou superior face a outros modelos de implementação mais simples.
The Domestic Demand of a country is essential for its economic activity as, for example, it can be considered an engine for the growth in production of goods and services. For Portugal, given the strong weight of private consumption in GDP, this effect is particularly relevant. Hence, to better describe the Portuguese economy, it is important to characterize the inter-dynamic relations between variables representative of the Demand and Production such as Consumption, Investment and GDP, so economic agents can anticipate changes and adapt their behavior. Therefore, with quarterly data for the period between the 1st quarter of 1999 and the 4th quarter of 2018, this study considered a vector autoregressive model (VAR) and was able to identify the major impact of the two components of Domestic Demand in the Production of goods and services and a not so evident relation in the opposite direction. Moreover, with the results from the estimated VAR model, we found evidence that the impact of exogenous shocks on the variables included in the system doesn't seem to last more than one year. Notwithstanding the statistical evidence of causality between Consumption, Investment and GDP, the model was outperformed, in terms of forecast accuracy, by standard univariate models.
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Marinovic, Alan. "Estudo da inter-relação entre os preços de ações bancárias da América Latina, Estados Unidos e Europa." reponame:Repositório Institucional do FGV, 2009. http://hdl.handle.net/10438/2619.
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Previous issue date: 2009-01-28T00:00:00ZO trabalho estuda a inter-relação entre preços de ações bancárias da América Latina, Estados Unidos e Europa durante o período compreendido entre janeiro de 2000 até final de junho de 2008. De um modo geral o estudo busca evidências sobre a existência de relações de equilíbrio de longo prazo entre as séries de preços utilizando análises de cointegração, testes de causalidade e funções de impulso resposta. Os resultados empíricos apontam para a existência de relações de equilíbrio de longo prazo entre as séries de preços, e para a existência de contágio especialmente de choques oriundos do mercado Norte Americano. Cabe ressaltar que o efeito de choques se mostra mais pronunciado após 2007, período compreendido pela crise do subprime.
This dissertation investigates the inter-relationships among bank’s stock markets for Latin America, United States and Europe from January, 2000 to June, 2008. The study analyzes the existence of long-run relationships among the price of Bank’s stocks, additionally it applies short-run causality tests and impulse response analyses. Empirical results suggests that there is at least one cointegration vector among the price series, and the series time paths are influenced by different extent of changes in price of different banks. Moreover the study finds that the relationships among bank’s stock prices differ between crises (more volatile) and less volatile periods. These findings imply that there are strong evidences of inter-connections among stock markets around the world.
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Akram, Muhammad. "Do crude oil price changes affect economic growth of India, Pakistan and Bangladesh? : A multivariate time series analysis." Thesis, Högskolan Dalarna, Nationalekonomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:du-10723.
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This paper analyzes empirically the effect of crude oil price change on the economic growth of Indian-Subcontinent (India, Pakistan and Bangladesh). We use a multivariate Vector Autoregressive analysis followed by Wald Granger causality test and Impulse Response Function (IRF). Wald Granger causality test results show that only India’s economic growth is significantly affected when crude oil price decreases. Impact of crude oil price increase is insignificantly negative for all three countries during first year. In second year, impact is negative but smaller than first year for India, negative but larger for Bangladesh and positive for Pakistan.
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Saleem, Rashid. "Towards an end-to-end multiband OFDM system analysis." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/towards-an-endtoend-multiband-ofdm-system-analysis(e711f32f-1ac6-4b48-8f4e-58309c0482d3).html.
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Ultra Wideband (UWB) communication has recently drawn considerable attention from academia and industry. This is mainly owing to the ultra high speeds and cognitive features it could offer. The employability of UWB in numerous areas including but not limited to Wireless Personal Area Networks, WPAN's, Body Area Networks, BAN's, radar and medical imaging etc. has opened several avenues of research and development. However, still there is a disagreement on the standardization of UWB. Two contesting radios for UWB are Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) and DS-UWB (Direct Sequence Ultra Wideband). As nearly all of the reported research on UWB hasbeen about a very narrow/specific area of the communication system, this thesis looks at the end-to-end performance of an MB-OFDM approach. The overall aim of this project has been to first focus on three different aspects i.e. interference, antenna and propagation aspects of an MB-OFDM system individually and then present a holistic or an end-to-end system analysis finally. In the first phase of the project the author investigated the performance of MB-OFDM system under the effect of his proposed generic or technology non-specific interference. Avoiding the conventional Gaussian approximation, the author has employed an advanced stochastic method. A total of two approaches have been presented in this phase of the project. The first approach is an indirect one which involves the Moment Generating Functions (MGF's) of the Signal-to-Interference-plus-Noise-Ratio (SINR) and the Probability Density Function (pdf) of the SINR to calculate the Average Probabilities of Error of an MB-OFDM system under the influence of proposed generic interference. This approach assumed a specific two-dimensional Poisson spatial/geometric placement of interferers around the victim MB-OFDM receiver. The second approach is a direct approach and extends the first approach by employing a wider class of generic interference. In the second phase of the work the author designed, simulated, prototyped and tested novel compact monopole planar antennas for UWB application. In this phase of the research, compact antennas for the UWB application are presented. These designs employ low-loss Rogers duroid substrates and are fed by Copla-nar Waveguides. The antennas have a proposed feed-line to the main radiating element transition region. This transition region is formed by a special step-generating function-set called the "Inverse Parabolic Step Sequence" or IPSS. These IPSS-based antennas are simulated, prototyped and then tested in the ane-choic chamber. An empirical approach, aimed to further miniaturize IPSS-based antennas, was also derived in this phase of the project. The empirical approach has been applied to derive the design of a further miniaturized antenna. More-over, an electrical miniaturization limit has been concluded for the IPSS-based antennas. The third phase of the project has investigated the effect of the indoor furnishing on the distribution of the elevation Angle-of-Arrival (AOA) of the rays at the receiver. Previously, constant distributions for the AOA of the rays in the elevation direction had been reported. This phase of the research has proposed that the AOA distribution is not fixed. It is established by the author that the indoor elevation AOA distributions depend on the discrete levels of furnishing. A joint time-angle-furnishing channel model is presented in this research phase. In addition, this phase of the thesis proposes two vectorial or any direction AOA distributions for the UWB indoor environments. Finally, the last phase of this thesis is presented. As stated earlier, the overall aim of the project has been to look at three individual aspects of an MB-OFDM system, initially, and then look at the holistic system, finally. Therefore, this final phase of the research presents an end-to-end MB-OFDM system analysis. The interference analysis of the first phase of the project is revisited to re-calculate the probability of bit error with realistic/measured path loss exponents which have been reported in the existing literature. In this method, Gaussian Quadrature Rule based approximations are computed for the average probability of bit error. Last but not the least, an end-to-end or comprehensive system equation/impulse response is presented. The proposed system equation covers more aspects of an indoor UWB system than reported in the existing literature.
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Koller, Simon. "Multiple Time Series Analysis of Freight Rate Indices." Thesis, KTH, Matematisk statistik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288500.
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In this master thesis multiple time series of shipping industry and financial data are analysed in order to create a forecasting model to forecast freight rate indices. The data of main interest which are predicted are the two freight rate indices, BDI and BDTI, from the Baltic Exchange. The project investigates the possibilities for aggregated Vector Autoregression(VAR) models to outperform simple univariate models, in this case, an Autoregressive Integrated Moving Average(ARIMA) with seasonal components. The other part of this thesis is to model market shocks in the freight rate indices, given impulses in the other underlying VAR-model time series using the impulse response function. The main results are that the VAR-model forecast outperforms the ARIMA-model in forecasting the tanker freight rate index (BDTI), while the the bulk freight rate index(BDI) is better predicted by the simple ARIMA when calculating the forecast mean square error.I denna avhandling analyseras multipla tidsserier över rederinärings- och finansiell data i syfte att skapa en prognosticerande modell för att prognosticera fraktratsindex. Dataserierna som i huvudsak prognosticeras är fraktratsindexen BDI och BDTI från Baltic exchange. I projektet undersöks om en aggregerad Vektor Autoregressiv(VAR) modell överträffar en univariat modell, i detta fall en Autoregressive Integrated Moving Average(ARIMA) med säsongsvariabel. I andra delen av denna avhandling modelleras chocker i fraktratsindexen givet impulser i de andra underliggande tidsserierna i de aggregerade VAR-modellerna. Huvudresultaten är att VAR-modellens prognos överträffar ARIMA-modellen för tankerraterna (BDTI), medan bulkraterna(BDI) bättre prognosticeras av ARIMA-modellen, i avseende på prognosernas beräknade mean square error.
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Štork, Zbyněk. "Term Structure of Interest Rates: Macro-Finance Approach." Doctoral thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-125158.
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Thesis focus on derivation of macro-finance model for analysis of yield curve and its dynamics using macroeconomic factors. Underlying model is based on basic Dynamic Stochastic General Equilibrium DSGE approach that stems from Real Business Cycle theory and New Keynesian Macroeconomics. The model includes four main building blocks: households, firms, government and central bank. Log-linearized solution of the model serves as an input for derivation of yield curve and its main determinants -- pricing kernel, price of risk and affine term structure of interest rates -- based on no-arbitrage assumption. The Thesis shows a possible way of consistent derivation of structural macro-finance model, with reasonable computational burden that allows for time varying term premia. A simple VAR model, widely used in macro-finance literature, serves as a benchmark. The paper also presents a brief comparison and shows an ability of both models to fit an average yield curve observed from the data. Lastly, the importance of term structure analysis is demonstrated using case of Central Bank deciding about policy rate and Government conducting debt management.
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Kárský, Vilém. "Modelování LTI SISO systémů zlomkového řádu s využitím zobecněných Laguerrových funkcí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316278.
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This paper concentrates on the description of fractional order LTI SISO systems using generalized Laguerre functions. There are properties of generalized Laguerre functions described in the paper, and an orthogonal base of these functions is shown. Next the concept of fractional derivatives is explained. The last part of this paper deals with the representation of fractional order LTI SISO systems using generalized Laguerre functions. Several examples were solved to demonstrate the benefits of using these functions for the representation of LTI SISO systems.
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Akpan, Nkereuwem I. "The Impact of External Shocks on Nigeria’s GDP Performance within the Context of the Global Financial Crisis." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17454.
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This research examines the impact of external shocks on Nigeria’s output performance for the period 1981 – 2015. It aims to bring to the fore the importance of considering external shocks during policy design and implementation. The multivariate VAR and VECM frameworks were used to evaluate the impact of the shock variables on Nigeria’s output performance and to achieve the stated objectives. Findings show that the external shock and domestic policy variables have short-run effects on Nigeria’s output performance. Also, all the measures of external shocks and domestic policies display some viable information in explaining the variabilities in Nigeria’s output performance over the horizon. The comparison between the results of the VECM and the unrestricted VAR shows that the unrestricted VAR model outperformed the VECM.
The overall result of the study confirms the view about the vulnerability of the Nigerian economy to external shocks. These shocks explain more than half of the variance in real output performance and have varying effects on output performance in Nigeria. The dynamic response of output performance to each of the defined shock variables show that output performance responds rapidly to the shock variables, while its response to the domestic economic variables is seemingly moderate. Finally, the variance decomposition show that international crude oil price and terms of trade have the largest share in accounting for the variability in output performance, followed closely by the shares of capital inflows and monetary policy.
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Singh, Shiu Raj. "Dynamics of macroeconomic variables in Fiji : a cointegrated VAR analysis." Diss., Lincoln University, 2008. http://hdl.handle.net/10182/774.
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Abstract of thesis submitted in partial fulfilment of the requirements for the Degree of Master of Commerce and Management Dynamics of macroeconomic variables in Fiji : a cointegrated VAR analysis By Shiu Raj Singh The objective of this study is to examine how macroeconomic variables of Fiji inter-relate with aggregate demand and co-determine one another using a vector autoregression (VAR) approach. This study did not use a prior theoretical framework but instead used economic justification for selection of variables. It was found that fiscal policy, which is generally used as a stabilisation tool, did not have a positive effect on real Gross Domestic Product (GDP) growth in the short term. Effects on GDP growth were positive over the long term but not statistically significant. Furthermore, expansionary fiscal policy caused inflationary pressures. Fiji has a fixed exchange rate regime, therefore, it was expected that the focus of monetary policy would be the maintenance of foreign reserves. It was, however, found that monetary expansion in the short term resulted in positive effects on real GDP growth and resulted in inflation. The long term effects of monetary policy on real GDP growth were negative, which are explained by the fixed exchange rate regime, endogenous determination of money supply by the central bank, an unsophisticated financial market and, perhaps, an incomplete transmission of the policy. Both merchandise trade and visitor arrivals growth were found to positively contribute to short term and long term economic growth. Political instability was found not to have significant direct effects on real GDP growth but caused a significant decline in visitor arrivals which then negatively affected economic growth in the short term.
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Antonakakis, Nikolaos, Ioannis Chatziantoniou, and George Filis. "Dynamic Spillovers of Oil Price Shocks and Economic Policy Uncertainty." WU Vienna University of Economics and Business, 2014. http://epub.wu.ac.at/4082/1/wp166.pdf.
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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
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Bodin, Oscar, and Jenny Nielsen. "Svenska aktiemarknaden : Hur påverkas den svenska aktiemarknaden av makroekonomiska variabler." Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-27537.
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Bakgrund och Problem: Aktiemarknaden påverkas både av inhemska och utländska faktorer. Därför är det av intresse att se vilka makroekonomiska variabler som påverkar den svenska aktiemarknaden. Anledningen till att Sverige har valts som den geografiska punkten är att det är av intresse att se hur ett litet land som Sverige, som har en öppen ekonomi påverkas av de utvalda makroekonomiska variablerna. Syfte: Syftet med uppsatsen är att med hjälp av information samt analys, studera hur de olika makroekonomiska variablerna påverkar den inhemska aktiemarknaden. Olika faktorer som påverkar aktiemarknaden kommer att lyftas fram för att i sin tur även se till de olika branscherna. Metod: Då data enbart består av hämtning av tidigare information fokuseras det enbart på sekundärdata i form av historiska siffror samt historiska undersökningar. De statistiska tester som tillämpas är Granger Causality test, Johansens Cointegration test, Impulse Response Function test, ADF test, KPSS test, Mulitpel regression. Slutsats: Med de resultat som presenterades i denna studie, skulle vi nog inte kunna säga att vi har ett svar över vilka aktier en investerare ska införskaffa. Dock skulle vi kunna poängtera att den potentiella investeraren bör ha dessa variabler i beaktning vid beslut. Genom att studera dessa variabler kan man få en känsla om vilket håll variablerna kommer att röra sig och på så sätt säga att de kan påverka aktieindexen. Att bara kolla på de makroekonomiska variabler som denna studie belyser räcker inte för att förstå hur aktieindex kommer att se ut i framtiden, men det är en bit på vägen till att förstå aktiemarknadens rörelse.
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Oliva, Rossella. "The impulsive brain: new insights into the neural correlates of binge eating in normal weight population." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426242.
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Despite humans are known to embody a unique ability to self-regulate, sometimes they act impulsively (Hofmann et al., 2009). Generally, impulsive behaviors may derive from the co-occurrence of dysfunctional inhibitory processes and strong urges to act (Bari and Robbins, 2013). In more detail, our impulses, if not appropriate to the situation, are usually kept under control by inhibitory mechanisms; however, when inhibition fails, impulsive acts may stem (Bari and Robbins, 2013). Researchers and mental health experts agree that impulsivity can boost the risk for a range of maladaptive behaviors, such as substance abuse (Kale et al., 2018; Loxton, 2018). Recently, drawing upon the surmised similarities between addiction and overeating (Gearhardt et al., 2009), some authors have hypothesized that the same impulsivity aspects that lead people to abuse alcohol or drugs may also lead to dysregulated eating. In support of this theory, recent studies have shown that individuals with eating disorders and obesity are more impulsive than healthy people, especially when binge eating behavior is present (Waxman, 2008). However, given that most of these investigations focused on people with full-blown eating or weight disorders, it is still unclear whether high impulsivity characterized these individuals also before the dysregulated eating began or if it developed as a result of it. Thus, little is known about the role of impulsivity as a potential risk and predisposing factor for binge eating within the general population. Based on these premises, the aim of the present thesis is to shed some new light on the role of impulsivity at the roots of binge eating behavior. Starting from the contemporary state of the art, Chapter 1 provides an overview of the definitions of the various facets of impulsivity and their neural correlates. Subsequently, Chapter 2 reviews some of the behavioral and neuroimaging studies exploring the relationship between impulsivity and eating behavior. From the existing state of knowledge, I emphasize the need for an in-depth exploration of the role of different impulsivity-related aspects in normal-weight individuals with binge eating. Hence, I outline the primary purposes of this project. First, given the well-established impact of eating and weight disorders on cognitive and neurobiological processes (Horstmann et al., 2015; Smith et al., 2011; van den Akker et al., 2014), I decided to focus on a non-clinical population of normal-weight individuals with binge eating, to provide a clearer account of the role of impulsivity as a hallmark of this behavior, regardless of weight status. Second, given that impulsivity comprises several related forms that depend on distinct neuropsychological processes and neural systems (Dalley and Robbins, 2017), I chose to assess this construct multi-modally, with self-reported, behavioral and neuroimaging measures, in the same study population, to disentangle the relative contribution of each component in the characterization of binge eating (Filbey and Yezhuvath, 2017). The second part of the thesis cover four experiments, in which, by comparing two groups of normal-weight individuals with and without binge eating, I aimed to explore: • General trait impulsivity, as assessed by self-reported questionnaires (Chapter 3); • Response inhibition abilities toward food, measured with food-specific Go/No-Go, GNG (Chapter 4) and Stop Signal Task, SST (Chapter 5); • Task-related brain activity during the execution of both tasks (Task-based functional MRI studies; Chapters 4 - 5); • Functional brain connectivity at rest (Resting-state functional MRI study; Chapter 6); • Brain morphometry (Voxel-based morphometry study; Chapter 7). In conclusion, the last chapter (Chapter 8) will draw upon the entire thesis, tying up the various theoretical and empirical strands in order to discuss the main findings of the experiments and their implication to future studies into this area.Nonostante una nostra caratteristica intrinseca sia quella di poter controllare e regolare il proprio comportamento, a volte agiamo in modo impulsivo (Hofmann et al., 2009). Un’azione impulsiva può derivare da processi inibitori deficitari uniti a forti impulsi ad agire: infatti, se di solito gli impulsi vengono tenuti a bada da un’efficiente capacità inibitoria, quando questa fallisce, il risultato può essere la messa in atto di comportamenti impulsivi (Bari e Robbins, 2013). Ad oggi, numerose evidenze riportano una chiara associazione tra impulsività e sviluppo di comportamenti maladattivi, come l’abuso di sostanze (Kale et al., 2018; Hogart, 2011). Recentemente, sulla base dell’ipotesi che dipendenze da sostanze e iperalimentazione condividano un substrato comune (Dawe and Loxton, 2004), alcuni ricercatori hanno ipotizzato che i tratti impulsivi che predispongono alle dipendenze, siano anche coinvolti nel discontrollo nei confronti del cibo (binge eating). Diverse ricerche hanno fornito un preliminare supporto a questa ipotesi, riportando una maggiore impulsività in individui affetti da obesità o disturbi alimentari, soprattutto quando presenti episodi di abbuffate (Waxman, 2009). Purtroppo però lo studio di persone con disturbi conclamati del peso o dell’alimentazione può fornire limitate informazioni sul motivo per cui alcune persone tendono a perdere il controllo nei confronti del cibo. Non si chiarisce cioè il ruolo dell’impulsività: è un tratto pre-estistente e di rischio per lo sviluppo delle abbuffate o è invece la risultante del perpetuarsi di questi comportamenti? Il presente elaborato intende mettere in luce il ruolo dell’impulsività alla base del binge eating. Nella prima parte, partendo dallo stato dell’arte, il Capitolo 1 si concentra sulla definizione delle diverse componenti dell’impulsività e sulle loro basi neurobiologiche. Seguendo la stessa struttura, il Capitolo 2 presenta alcuni studi che indagano l’impulsività e i suoi correlati in relazione al comportamento alimentare. Grazie all’analisi della letteratura, ho evidenziato la necessità di un’indagine del ruolo di diverse componenti dell’impulsività in individui sani, con episodi di binge eating. In particolare, visto l’impatto di disturbi alimentari e del peso sui processi cognitivi e neurobiologici (Horstmann et al., 2015; Smith et al., 2011; van den Akker et al., 2014), ho deciso di condurre lo studio considerando persone normopeso con episodi di binge eating, per comprendere il ruolo dell’impulsività come caratteristica alla base di questo comportamento, indipendentemente dalla presenza di disturbi alimentari o del peso. Inoltre, considerato che il termine impulsività racchiude in sé varie componenti, sottese da diversi substrati neurobiologici (Dalley e Robbins, 2017), ho scelto di indagare questo costrutto usando molteplici misure (questionari, compiti comportamentali, e tecniche di neuroimmagine), nella stessa popolazione, al fine di comprende il contributo di ogni dimensione nella caratterizzazione del binge eating. La parte sperimentale della tesi si compone di quattro studi, nei quali, confrontando due gruppi di persone con e senza episodi di binge eating, ho esplorato i seguenti aspetti: • Impulsività di tratto, tramite questionari autosomministrati (Cap. 3) • Capacità di inibizione della risposta motoria nei confronti del cibo, attraverso: Go/No-Go, GNG (Cap. 4) e Stop Signal Task, SST (Cap. 5) • Attività cerebrale durante l’esecuzione di GNG e SST (task-based fMRI study; Cap. 4-5) • Connettività funzionale a riposo (resting-state fMRI study; Cap. 6) • Morfometria cerebrale (Voxel-based Morphometry study; Cap. 7) In conclusione, il Capitolo 8, sulla base del cappello teorico introduttivo e dei risultati degli esperimenti, propone una discussione generale dei risultati e le loro implicazioni per future ricerche in questo campo.
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Huston, Steven Paul. "Structural health monitoring of a high speed naval vessel using ambient vibrations." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33848.
Full textAbstract:
Traditional naval vessels with steel structures have the benefit of large safety factors and
a distinct material endurance limit. However, as performance requirements and budget
constraints rise, the demand for lighter weight vessels increases. Reducing the mass of
vessels is commonly achieved by the use of aluminum or composite structures, which
requires closer attention to be paid to crack initiation and propagation. It is rarely
feasible to require a lengthy inspection process that removes the vessel from service for
an extended amount of time. Structural health monitoring (SHM), involving continuous
measurement of the structural response to an energy source, has been proposed as a step
towards condition-based maintenance. Furthermore, using a passive monitoring system
with an array of sensors has several advantages: monitoring can take place in real-time
using only ambient noise vibrations and neither deployment of an active source nor visual
access to the inspected areas are required.
Passive SHM on a naval vessel is not without challenge. The structures of ships are
typically geometrically complex, causing scattering, multiple reflections, and mode
conversion of the propagating waves in the vessel. And rather than a distinct and
predictable input produced by controlled active sources, the vibration sources are hull
impacts, smaller waves, and even onboard machinery and activity. This research
summarizes findings from data collected onboard a Navy vessel and presents
recommendations data processing techniques. The intent is to present a robust method of
passive structural health monitoring for such a vessel using only ambient vibrations
recordings.
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Zanetta, Neto Ary Cera. "Efeitos de choques globais na economia brasileira: uma análise a partir do GVAR." reponame:Repositório Institucional do FGV, 2014. http://hdl.handle.net/10438/11935.
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O objetivo deste estudo é avaliar a propagação de choques econômicos de alguns países sobre o crescimento econômico brasileiro, com principal destaque para China, Estados Unidos da América (EUA) e Argentina, que são os principais parceiros comerciais do Brasil. O aumento do comércio com a China tornou o Brasil muito mais vulnerável a choques no PIB chinês e menos vulnerável, do que no passado recente, a choques no PIB americano, enquanto que a influência da Argentina manteve-se estável. Foi aplicada a metodologia Vetor Autorregressivo Global (Global Var – GVAR), introduzida por Pesaran, Schuermann e Weiner (2004), Garratt, Lee, Pesaran e Shin (2006) e Dées, Di Mauro, Pesaran e Smith (2007), para analisar os canais de comércio e a transmissão de choques entre o resto do mundo e o Brasil. Usando dados trimestrais a partir de 1990 até o final de 2013, foi possível constatar que o aumento da relevância da economia Chinesa na balança comercial Brasileira exerce pressão sobre o crescimento econômico do Brasil. Em suma, a China tornou-se mais relevante para o crescimento econômico do Brasil do que os EUA e a Argentina.
The objective of this study is to evaluate the impact of variations in the Gross Domestic Product (GDP) of countries and economic blocks over Brazilian economic growth, with emphasis on China, United States of America (USA) and Argentina, which are the main commercial partners of Brazil. The increase in trading with China has made Brazil more vulnerable to shocks in Chinese GDP and less vulnerable, than in the recent past, to shocks in American GDP, and stability in the case of Argentina. It has been applied the methodology Global Vector Autorregressive (Global Var – GVAR), introduced, explained and expanded by Pesaran, Schuermann and Weiner (2004), Garratt, Lee, Pesaran and Shin (2006) and Dées, Di Mauro, Pesaran and Smith (2007) to analyze the trading channels and the transmission of shocks between the rest of the world and Brazil (specially with China, USA and Argentina). Using a sample from the first quarter of 1990 to the third quarter of 2013 it is possible to see that the increase of relevance of the Chinese economy on the Brazil trade balance increased the relevance of the Chinese economy over the Brazilian economy. Therefore, the conclusions of this work indicate a considerable vulnerability of the Brazilian economy to the Chinese economic cycle and, in a lower degree than in the past, to the American and Argentinian economies.
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Malafaia, Karla de Alvarenga Charles. "Análise dos impactos da linha Finem na produção industrial brasileira por meio de vetores autoregressivos." reponame:Repositório Institucional do FGV, 2013. http://hdl.handle.net/10438/10562.
Full textAbstract:
Submitted by Karla Malafaia (karlamalafaia@gmail.com) on 2013-02-26T23:31:57Z
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Este trabalho se propõe a testar e quantificar a importância do investimento de longo prazo, captado pela série de desembolsos da linha BNDES Finem, na produção industrial brasileira. Através dos modelos de causalidade de Granger e Função resposta ao impulso, podemos verificar as respostas acumuladas ao longo de três anos da linha Finem a choques positivos de um desvio padrão nas variáveis inflação, produção industrial, spread, e, da mesma forma um choque na variável Finem com resposta nas variáveis acima descritas. Além disso, é possível identificar a importância do BNDES como um ator anticíclico em períodos de crise como na economia brasileira. Como resultado, encontramos que apesar dos desembolsos Finem não Granger causarem a produção industrial brasileira, se testadas em conjunto com dados de inflação e a diferença entre a Selic e a TJLP rejeita-se a hipótese nula de não causalidade a 1% de significância. Já os testes de funções de resposta ao impulso indicam que a taxa de crescimento da produção industrial tem resposta positiva a um choque de desvio padrão nos desembolsos de Finem. Contudo, se testada em conjunto um choque no Finem apesar de impactar positivamente a produção industrial acaba pressionando a inflação.
This work is to test and quantify the importance of a long-term investment captured by the series of disbursements of BNDES Finem line in brazilian industrial production. Through Granger causality and impulse-response function, it was possible to check the Finem line accumulated answers along three years to positive shocks of a standard deviation on the variables inflation, industrial production, spread, and a shock on Finem variable with answer on the previous described variables. Furthermore, it's possible to identify the BNDES's importance as a countercyclical tool in crisis period as in brazilian economy. As a result, we found that despite causing the brazilian industrial production, if the no Granger Finem's disbursements are tested with inflation data and the difference between Selic and TJLP, the null hypothesis of no causality at 1% of significance is rejected. Yet, the tests of impulse-response function indicate that the industrial production growth rate has positive answer to a shock of standard deviation on Finem's disbursements. However, despite impacting the industrial production positevely, it pressures the inflation if it's tested with a shock on Finem.
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Sun, Yurong. "Ultrasound characterization of structure and density of coral as a model for trabecular bone." Link to electronic version, 2000. http://www.wpi.edu/Pubs/ETD/Available/etd-0808100-001812/.
Full textAbstract:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: angular decorrelation function; impulse response; BUA; BMD; ultrasound; coral; trabecular bone; osteoporosis. Includes bibliographical references (p. 189-191).
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Song, In Ho. "Essays on House Prices and Consumption." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306848116.
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