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Azevedo, Joaquim

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D417-D5FC-FAC3
0000-0002-9060-7476

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1993 - 19953
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End date: 1999 × Start date: 1993 ×

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Now showing 1 - 3 of 3
  • On the use of Fourier transform with acoustical fields
    Publication . Casimiro, António Manuel E. S.; Azevedo, Joaquim A. R.
    The Fourier Transform is a powerful tool to deal with the radiated far field pattern of source distributions [l], PI. In this paper it is made a theoretical introduction to the possibility of using the Fourier Transform to study the fields produced by distributions, either continuous or discrete, of acoustical source distributions. With this new approach we can have a deep insight in the field and it is possible to develop and simplify methods of analysis and synthesis of fields produced by acoustical sources. All the procedure is based on the Theorem of the Small Complex Translation presented. In this case, and with a convenient choice of variables, the far field pattern is related with an window on the Fourier Transform of source distribution. The analysis and synthesis are made using the Fourier Transform firoprieties and the tools provided by the signal processing theory using the Fourier Transform
    1993Conference object Metadata only Show more
  • Dealing with the useful window related with the far field pattern
    Publication . Casimiro, António Manuel E. S.; Azevedo, Joaquim A. R.; Grilo, Alberto J. V. V.
    With a convenient representation, the radiation pattern of a spatial distribution of radiating sources is always related with that distribution by a window in the inverse Spatial Fourier Transform of the distribution. This fact is used to change the distribution of sources without disturbing the radiation pattern. On the other hand, the error, in the mean square sense, made by source elimination is also related with the Fourier Transform of the distribution. So it spreads all over the domain and not only inside the useful window. This must be taken in account and, with some signal processing, it is possible to find the error only in the far field pattern using the spatial distributions of sources.
    1995Conference object Metadata only Show more
  • Localização e simulação de som tridimensional
    Publication . Azevedo, Joaquim Amândio Rodrigues
    1994Master thesis Open access Show more