Estimation of Exoplanetary Planet-to-Star Radius Ratio with Homomorphic Processing

In this paper a homomorphic filtering scheme is proposed to improve the estimation of the planet/star radius ratio in astronomical transit signals. The idea is to reduce the effect of the short-term earth atmosphere variations. A two-step method is presented to compute the parameters of the transit curve from both the unfiltered and filtered data. A Monte Carlo analysis is performed by using correlated and uncorrelated noise to determine the parameters of the proposed FFT filter. The method is tested with observations of WASP-19b and WASP-17b obtained with the FORS2 instrument at the Very Large Telescope (VLT). The multi parametric fitting and the associated errors are obtained with the JKTEBOP software. The results with the white light of the exo-planet data mentioned above suggest that the homomorphic filtering can lead to substantial relative reductions in the error bars as high as 45.5% and 76.9%, respectively. The achieved reductions in the averaged error bars per channel were 48.4% with WASP-19b and 63.6% with WASP-17b. Open source MATLAB code to run the method proposed here can be downloaded from http://www.cmrsp.cl. This code was used to obtain the results presented in this paper

Reconhecimento automatico de palavras isoladas : estudo e aplicação dos metodos deterministico e estocastico

Orientador: João Marcos Travassos RomanoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia EletricaResumo: Esta dissertação objetiva o estudo e implementação das técnicas mais comumente utilizadas em reconhecimento de palavras isoladas, numa abordagem analítica e crítica. Neste sentido, os dois primeiros capítulos foram dedicados à apresentação dos métodos de parametrização e de reconhecimento de padrões acústicos, utilizando um certo rigor matemático, tendo sempre em vista as aplicações. A seguir, foram comparadas três técnicas de parametrização (coeficientes LPC, LPC-cepstral e Mel-cepstral) no que diz respeito à capacidade de assimilar características intra-locutor e inter-locutor, e quanto à robustez em relação ao ruído interferente. Para implementar estes testes comparativos foi sugerido o algoritmo DTW (método determinístico) que compara diretamente duas elocuções eliminando as diferenças temporais entre elas. Por último, foi descrita a implementação de um reconhecedor automático de dígitos independente do locutor empregando a técnica HMM (método estocástico) com modelamento por palavra e parametrização Mel-cepstralAbstract: In this work, the most commonly used techniques employed in speech recognition for isolated words were studied and implemented. Initially the parametrization and acoustic pattern recognition methods were discussed. In the discussion, we not only maintained the mathematical formalism as suggested in the literature but also sought the easy way for the practical implementation of these techniques. Three parametrization techniques, namely LPC,LPC-cepstral and Mel cepstral coefficients, were compared with respect to the assimilation capability of speaker-dependent and independent features, and noise robustness. Particularly, the DTW technique (deterministic analysis) was used for these comparative tests, which is capable of eliminating the time difference between two elocutions. A speaker independent digit recognizer was implemented employing the HMM techniques (stochastic analysis) with word modelling and Mel-cepstral coefficientsMestradoMestre em Engenharia Elétric