The recent boom in 21cm astronomy has piqued the interest of many, especially cosmologists realizing its applications in their field. This study aims to determine if 21cm astronomy is a good tool for testing the validity of keV WDM models, as well as creating a code capable of simulating keV WDM models from an existing CDM code. The assumed WDM models vary only in dark matter particle mass and assume a single-species dark matter case as well as totally thermalized particles, such as gravitinos. Small-scale simulations of approximately 183Mpc3, as well as large-scale simulations of approximately 1503Mpc3-1793Mpc3, indicated that the CDM code was successfully modified to simulate WDM through the total dark matter power spectrum and the halo-mass function. Additionally, the large-scale simulations hinted at a positive use of 21cm astronomy for the restriction of keV WDM models, due to the existence of a distinct CDM HI power spectrum as compared to the 0.5keV WDMHI power spectrum. A discernable difference between CDM and keV WDM galactic HI power spectra would provide a step towards a confirmation or falsification of keV WDM models if supplied with a large-scale galactic HI power spectrum study

Yes / Based on the previous studies, the shallow water equations (SWEs) model was proven to be insufficient to consider the flow turbulence due to its simplified Reynolds-averaged form. In this study, the k-ε model was used to improve the ability of the SWEs model to capture the flow turbulence. In terms of the numerical source terms modelling, the combined k-ε SWEs model was improved by a recently proposed surface gradient upwind method (SGUM) to facilitate the extra turbulent kinetic energy (TKE) source terms in the simulation. The laboratory experiments on both the smooth and rough bed flows were also conducted under the uniform and non-uniform flow conditions for the validation of the proposed numerical model. The numerical simulations were compared to the measured data in the flow velocity, TKE and power spectrum. In the power spectrum comparisons, a well-studied Kolmogorov’s rule was also employed to complement both the numerical and experimental results and to demonstrate that the energy cascade trend was well-held by the investigated flows. / The Major State Basic Research Development Program (973 program) of China (Grant Number 2013CB036402). Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, China (Grant Number SKLH-OF-1103).

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O presente trabalho tem como objetivo desenvolver novas alternativas de identificação modal para estruturas sob excitações em condição de operação baseadas em funções de transmissibilidade. Recentes metodologias formuladas sobre conceitos de transmissibilidade têm surgido como alternativa para a identificação de parâmetros modais de estruturas. A identificação nestas metodologias é independente do espectro da excitação, sendo uma vantagem importante com respeito a metodologias anteriores no domínio da frequência que supõem a excitação como ruído branco. Dessa forma, aproveitando os diferentes trabalhos dirigidos a avaliar parâmetros modais com uso da transmissibilidade, são propostas três novas alternativas. A primeira delas propõe a decomposição de valores singulares sobre matrizes de funções de transmissibilidade escalar com densidade espectral para estimar frequências naturais e modos de vibração. A segunda alternativa propõe o conceito de funções de transmissibilidade multivariável com diferente referência para a identificação modal. E a terceira introduz uma melhora na primeira alternativa incluindo a possibilidade da estimação de taxas de amortecimento. Uma ferramenta computacional para a análise modal é desenvolvida como apoio para as simulações numéricas de verificação das metodologias de identificação modal propostas. Diferentes exemplos numéricos com uma viga submetida a excitações de ruído colorido mostram que os métodos propostos são capazes de identificar parâmetros modais sem a introdução das frequências adicionais devido às excitações de ruído colorida utilizadas. Além disso, os dados de um teste de vibrações sobre uma ponte em operação foram utilizados para verificar os métodos. / This research aims to develop new alternatives of modal identification for structures under excitation in operation condition based on transmissibility functions. Latest methodologies based on transmissibility concepts have been arising as alternatives for modal parameter identification of structures. Modal parameter identification in this type methodology is input spectrum independent being an important advantage with respect previous frequency domain methods that assumes white noise excitation. Different alternatives of modal identification based on transmissibility functions are proposed in this work. The first of them proposes singular value decomposition on scalar transmissibility functions matrices with spectral density to estimate natural frequencies and vibration modes (PSDTM-SVD method). A second alternative proposes the concept of multivariable transmissibility functions with different transferring outputs for modal parameter identification. And the third alternative proposes an enhanced PSDTM-SVD method, which permits to identify modal damping. Computational tool for modal analysis is developed as a support for the numerical simulations of verification of modal identification methodologies proposed. Different numerical examples of a beam model subjected to colored noise excitations show that the proposed methods are capable of identifying modal parameters without the introduction of the additional frequencies due to the excitations used. Furthermore, data from an operational vibration bridge test were used to verify the methods.

This work is concerned with the response of a Blasius boundary layer to dielectric-barrier-discharge (DBD) plasma actuators for the purpose of using these devices in bypass transition control. The plasma actuators consist of a spanwise-periodic array of high voltage electrodes, which are oriented to produce streamwise vortex pairs. The structure of actuator-induced streaks is measured using hot-wire anemometry over a streamwise distance of approximately 100 boundary layer thicknesses, and is decomposed into 4 spanwise Fourier modes. The modal content and corresponding streamwise growth characteristics are discussed for ten plasma actuator geometries over multiple excitation voltages and freestream velocities. Actuator power consumption was found to control the streak amplitude, whereas freestream velocity affected both amplitude and streamwise extent of the streaks. A common relationship between disturbance energy and power consumption was found among actuators of different dielectric thickness and similar electrode geometry.

This work is concerned with the response of a Blasius boundary layer to dielectric-barrier-discharge (DBD) plasma actuators for the purpose of using these devices in bypass transition control. The plasma actuators consist of a spanwise-periodic array of high voltage electrodes, which are oriented to produce streamwise vortex pairs. The structure of actuator-induced streaks is measured using hot-wire anemometry over a streamwise distance of approximately 100 boundary layer thicknesses, and is decomposed into 4 spanwise Fourier modes. The modal content and corresponding streamwise growth characteristics are discussed for ten plasma actuator geometries over multiple excitation voltages and freestream velocities. Actuator power consumption was found to control the streak amplitude, whereas freestream velocity affected both amplitude and streamwise extent of the streaks. A common relationship between disturbance energy and power consumption was found among actuators of different dielectric thickness and similar electrode geometry.

In security markets, the stock price movements are closely linked to the market information. For example, the subprime mortgage triggered a global financial crisis in 2007. Drops occurred in virtually every stock market in the world. After the Federal Reserve took several steps to address the crisis, the stock markets have been gradually stable. Reaction of the traders to the arrival information results in different patterns of the stock price movements. Thus pattern matching is an important subject in future movement prediction, rule discovery and computer aided diagnosis. In this research, we propose a pattern matching procedure to seize the similar stock price movements of two listed companies during one day. First, the algorithm of searching the longest common subsequence is introduced to sieve out the time intervals where the two listed companies have the same integrated volatility levels and price rise/drop trends. Next we transform the raw price data in the found matching time periods to the Bollinger Band Percent data, then use the power spectrum to extract low frequency components. Adjusted Pearson chi-squared tests are performed to analyze the similarity of the price movement patterns in these periods. We perform the study by simulation investigation first, then apply the procedure to empirical analysis of high frequency transaction data of NYSE.

[pt] Sistemas com múltiplas antenas transmissoras e receptoras, também conhecidos como sistemas MIMO (Multiple Input-Multiple Output), têm sido apontados como uma solução para aumentar a capacidade de enlaces sem fio, permitindo aos usuários utilizar aplicações com altas taxas de dados. Isto é extremamente importante em sistemas onde a capacidade obtida com as técnicas tradicionais é bastante limitada devido às características do ambiente de propagação. Com o sistema MIMO, algumas destas características são exploradas para criar canais paralelos e obter aumento expressivo de capacidade. A análise da capacidade de sistemas MIMO se baseia em uma modelagem desenvolvida a partir do comportamento estatístico dos pares de enlaces existentes entre as múltiplas antenas transmissoras e receptoras. Existe, portanto, um grande interesse em medir este comportamento para situações típicas bem como em relacioná-lo a determinados parâmetros do sistema. Nesta tese apresentam-se os resultados de uma campanha de medidas visando caracterizar canais MIMO de faixa estreita e faixa larga em ambientes fechados (indoor) com uma freqüência de portadora de 2GHz. A partir dos dados medidos, avalia-se a capacidade e diversos parâmetros do canal espaço-temporal. Os parâmetros do canal MIMO são estimados através do algoritmo FD-SAGE e as dispersões temporal e espacial do canal são calculadas a partir dos parâmetros estimados. Uma análise dos autovalores da matriz do canal MIMO é realizada com o objetivo de relacionar os valores da capacidade ao número de canais paralelos. É analisada, ainda, a correlação entre a capacidade e os parâmetros físicos do canal, tais como espaçamento entre os elementos do arranjo, espalhamento angular, espalhamento dos retardos, número e potência dos multipercursos. / [en] Multiple antenna systems known as MIMO (Multiple Input Multiple Output) systems have been proposed as an effective way to address the user demand for high data rate applications in wireless systems. This is especially important in systems where the capacity attained with traditional techniques is very limited due to the adverse characteristics of the propagation environment. With MIMO, some of these characteristics are used to create parallel channels producing significant increase in capacity. The analysis of MIMO capacity is based on models developed from the statistical behavior of the multiple links between the transmitting and receiving antennas, and therefore there has been large interest in measuring these characteristics in typical scenarios and in relating the data to system parameters. In this thesis the results of a MIMO wideband measurement campaign carried out in an indoor scenario with a carrier frequency of 2 GHz is presented. The wideband and narrowband channel capacity and several channel parameters are evaluated from the measured data. The channel parameters are estimated using the frequency domain Space-Alternating Generalized Expectation maximization (FD- SAGE) algorithm. Temporal and spatial dispersions of the multipath channel are calculated from the estimated parameters and an eigenvalue analysis is performed seeking to relate the capacity values to the number of parallel channels. In addition, the correlation between channel capacity and physical parameters as antenna spacing, angle spread, delay spread, number and power of multipath components is investigated.

The operating motion of a ground compactor uses high power vibrations to improve mechanical properties of a compacted ground. This motion gives a good base for the vibration analysis with an aid of Signal Processing. In this thesis, the motion of a bottom plate in a compactor is of the main interest. The thesis concerns usage of two main spectral analyzing tools, Power Spectrum estimators and Power Spectral Density estimators, presenting advantages and disadvantages in the application of a vibration analysis. Moreover, an influence of two window applications, a Flattop window, and a Hanning window, is described in relation to both analyzing approaches. The results present problems that occur when a vibration with a present modulated frequency is analyzed and how a Power Spectral Density estimator arise in a more consistent estimate over analyzed vibration spectrum. What is more, an Ordinary Deflection Shapes for a simplified bottom plate model, under different motion excitations, are presented at the end of this thesis, giving a better view of the operational motion of an analyzed system.

This study proposes an approach to analyze EMG signals using wavelets transformed as a method of signal features extraction. The adopted methodology is based on the study of the aggregated power envelope and the aggregate power spectrum envelope, which are obtained from the distribution of energy of a certain signal, based on the potency of wavelet coefficients, showed like wavelets spectrograms or from a wavelet scalegram. EMG signals were captured in the surface of the human skin and came from the right leg rectus femoris muscle in a static condition (isometric), also from the flexor muscle form the right hand in dynamic contraction (isotonic) and also form a train of motor unit action potential (MUAP) form the First Dorsal Interosseous muscle during dynamic contraction. Having those signals, there were taken two research phases: extraction of the feature based on the analytical wavelet transformed (AWT) in muscles during contraction (isometric and isotonic) and the phase of detection of MUAPs. In the AWT phase, considering the calculation of the envelopes in the timefrequency chart (spectrogram), the results shoed that the wavelet transformed can be applied for extraction of spectral content of the signal and also showed the possibility of verifying the potency signal spectrum and the energy of such signal intimae. Those variables were according to the expected features for EMG signal, reported by literature. In the second phase, MUAP detection, it was used the calculation of the envelopes based on the scalegram, having as a main wavelet the Daubechies of 4 (db4), Coiflet of 4 (coif4) and Symlet of 5 (sym5) . The result showed that the method allowed to locate in time of MUAPs and showed that it is sensible enough to detect signals form motor units, far from the sensor, which contribute to formation of the EMG signal. The use of the wavelet Db4 showed to be better to detect the muscle activity on the beginning of it ( set-on ), because the Db4 is similar to a MUAP. This work proposes that future studies can be based on the research of families of wavelets, using of the method of the aggregated power envelope to control proteases for arms, or hands for example. It is also proposed studies for detection of MUAPs as an important tool for muscles evaluation, in diagnosis of miopathologies and neuro-muscle disjunctions, envelope features extraction process for other biomedical signals, such as EEG and ECG. / Este trabalho propõe uma abordagem para a análise de sinais EMG utilizando as transformadas wavelet como método de extração de características do sinal. A metodologia aplicada utiliza o estudo da envoltória de potência agregada e da envoltória do espectro de potência agregada, que são extraídas a partir da distribuição de energia de um sinal, baseada na potência dos coeficientes wavelets exibidos sob a forma de espectrograma wavelet ou de escalograma wavelet. Os sinais EMG foram captados na superfície da pele e são oriundos, do músculo reto da coxa direita em contração estática (isométrica), do músculo flexor de punho direito em contração dinâmica (isotônica) e de um trem de potenciais de ação de unidade motora (MUAPs) do músculo primeiro dorsal interósseo em contrações dinâmicas. Com estes sinais, duas fases de investigação foram abordadas, as quais são: a fase de extração de característica baseada na transformada wavelet analítica nos músculos em contração (isométrica e isotônica) e a fase de detecção de MUAPs. Na fase baseada na transformada wavelet analítica (AWT), através dos cálculos das envoltórias na localização do plano tempo-freqüência (espectrograma), o resultado obtido foi que a transformada wavelet pode ser aplicada para extração do conteúdo espectral do sinal, e foi possível verificar que o espectro de potência do sinal e a energia deste sinal ao logo do tempo se mostraram dentro das características esperadas para o sinal EMG reportadas pela literatura. Na fase de detecção de MUAPs, utilizando o cálculo das envoltórias baseado no escalograma (diagrama tempo-escala), tendo como wavelet-mãe a Daubechies de ordem 4 (db4), Coiflet de ordem 4 (coif4) e Symlet de ordem 5 (sym5) , o resultado mostrou que o método permitiu a localização no tempo dos MUAPs e demonstrou que é sensível o suficiente para detectar sinais de unidades motoras distantes do sensor, os quais, contribuem para a formação do sinal EMG. O uso da wavelet Db4 mostrou-se melhor na detecção do início da atividade muscular ( set-on ) pois a Db4 se a semelha a uma MUAP. Este trabalho sugere que trabalhos futuros poderão ser baseados na investigação de famílias wavelets para análise de sinais EMG, bem como a utilização do método de envoltória de potência agregada para controle de próteses de membros superiores, a utilização de wavelets para detecção de MUAPs como uma importante ferramenta na avaliação muscular, no diagnóstico de miopatologias e disfunções neuromusculares e também a extração de características por envoltória para outros sinais biomédicos, como por exemplo, o EEG, o ECG etc. / Mestre em Ciências