In this paper we describe three computer programs in Basic language about the Fourier transform (FFT) which are available in the Internet site http://artemis.ffclrp.usp.br/SoftwareE.htm (in English) or http://artemis.ffclrp.usp.br/softwareP.htm (in Portuguese) since October 1998. Those are addresses to the Web Page of our Laboratory of Organic Synthesis. The programs can be downloaded and used by anyone who is interested on the subject. The texts, menus and captions in the programs are written in English.

This paper describes the development of an electronic system that automatically recognises the sound of a referee whistle in a nosy environment It can be directly adapted to any robot on a robotic competition namely robotic football Experiments have been conducted in order to test the developed system and results are shown

https://repositorium.sdum.uminho.pt/bitstream/1822/16155/1/CN07.pdf

Whistle sound recognition in a noisy environment

As ondas acústicas ou sonoras são ondas mecânicas que dependem de um meio para se propagarem e a partir de algumas propriedades como a velocidade de propagação e atenuação torna-se possível realizar medidas desta propagação, sendo a temperatura um fator importante a ser considerado. O método baseado na propagação de ondas acústicas transferidas para o meio em estudo emprega sensores acústicos para detectá-las. Uma das vantagens está no fato de ser não destrutivo, com a possibilidade de ser não invasivo e usado em aplicações de linha. Assim, pode ser utilizado para análise de várias matrizes, como alimentos, sendo bastante utilizado na análise de líquidos. Neste trabalho foi construído um espectrômetro de som para análise de componentes majoritários em matrizes líquidas, utilizando-se como transdutores, elementos piezoelétricos para uma faixa de frequência de 100 Hz a 20 kHz. Foram desenvolvidas células de diferentes tamanhos e formatos. Observou-se a importância do controle da temperatura e da distância entre os elementos piezoelétricos. Em particular, quanto maior a distância, maior a atenuação observada enquanto, abaixo de 4 mm foi observado a sobreposição de bandas. Foi possível discriminar diferentes matrizes líquidas, tais como soluções puras de sacarose, etanol, lactose, ácido acético e soluções de leites (integral e zero lactose) com auxílio da análise de componentes principais. Com auxílio da regressão por quadrados mínimos parciais, foi possível a quantificação de sacarose, etanol e ácido acético em uma mistura destes, assim como a determinação de teor alcóolico em vinhos, com um erro relativo de -3,92 a 2,35% quando comparado ao método de referência e uma estimativa do desvio padrão dos resíduos igual a 0,012. O instrumento desenvolvimento mostrou-se eficaz, prático e robusto, além de apresentar um baixo custo relativo à sua montagem. Palavras-chave: Quimiometria. Detectores. Análise de Regressão. 

Espectrômetro de som para análise de componentes majoritários em matrizes líquidas

Socio-economic analysis of the administrative regions of the city of Vitória/ES using graph signal processing

/pdf/a-transformada-de-fourier-em-basic-28tny7ii8z.pdf

A transformada de Fourier em basic

In §13.5 we learned something about the construction and application of digital filters, but little guidance was given on which particular filter to use. That, of course, depends on what you want to accomplish by filtering. One obvious use for low-pass filters is to smooth noisy data. The premise of data smoothing is that one is measuring a variable that is both slowly varying and also corrupted by random noise. Then it can sometimes be useful to replace each data point by some kind of local average of surrounding data points. Since nearby points measure very nearly the same underlying value, averaging can reduce the level of noise without (much) biasing the value obtained. We must comment editorially that the smoothing of data lies in a murky area, beyond the fringe of some better posed, and therefore more highly recommended, techniques that are discussed elsewhere in this book. If you are fitting data to a parametric model, for example (see Chapter 15), it is almost always better to use raw data than to use data that has been pre-processed by a smoothing procedure. Another alternative to blind smoothing is so-called " optimal " or Wiener filtering, as discussed in §13.3 and more generally in §13.6. Data smoothing is probably most justified when it is used simply as a graphical technique, to guide the eye through a forest of data points all with large error bars; or as a means of making initial rough estimates of simple parameters from a graph. In this section we discuss a particular type of low-pass filter, well-adapted for data smoothing, and termed variously Savitzky-Golay [1], least-squares [2], or DISPO (Digital Smoothing Polynomial) [3] filters. Rather than having their properties defined in the Fourier domain, and then translated to the time domain, Savitzky-Golay filters derive directly from a particular formulation of the data smoothing problem in the time domain, as we will now see. Savitzky-Golay filters were initially (and are still often) used to render visible the relative widths and heights of spectral lines in noisy spectrometric data. Recall that a digital filter is applied to a series of equally spaced data values fi ≡ f (ti), where ti ≡ t0 + i∆ for some constant sample spacing ∆ and i =. .. We have seen (§13.5) that the simplest type of digital filter (the nonrecursive or finite impulse response filter) replaces each data value fi …

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A transformada de Fourier em basic

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Whistle sound recognition in a noisy environment

Espectrômetro de som para análise de componentes majoritários em matrizes líquidas

Socio-economic analysis of the administrative regions of the city of Vitória/ES using graph signal processing

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