In this paper we discuss the sound absorption property of arrays of micro-acoustic actuators at a control surface. We use the wave equation over the half plane for the velocity potential with a boundary dissipation by a proportional pressure feedback law along the half plane boundary. The feedback gain over the array is described by a distributed shape function. We develop a computational metho...

The purpose of this paper is to give a very short, \nuts and bolts", introduction to the lifting scheme and provide references for further reading. The lifting scheme is a new method for constructing biorthogonal wavelets. The main di erence with classical constructions [1-3] is that it does not rely on the Fourier transform. This way lifting can be used to construct second generation wavelets,...

In this paper we apply the wavelets methodology to the analysis of the comovements of for some MENA countries from June 1997 until March 2005. We decompose weekly stock market returns into di¤erent time scale components using the non-decimated discrete wavelet transform and then analyze the relationships among these variables at the di¤erent time scales. Keywords : Stock market returns, Wavelet...

The scheduling of systems of periodic tasks upon multiprocessor systems with processors of di ering speeds is considered. Computation speeds may di er because the system is comprised of di erent types of processors | i.e. it may be a uniformmultiprocessor platform. Alternatively, the platform may be comprised of identical processors with speeds that di er because some processors may have their ...

one of the common problems in reflective seismic records is the existence of coherent linear and random noises which cause covering of the most important parts of reflective signals; therefore, it is necessary to attenuate them by processing methods. several processing techniques have been devised for attenuation of coherent linear noises and linear radon or ?-? transform is a powerful techniqu...

In this paper we present results that indicate that the formant frequencies between di erent speakers scale di erently at di erent frequencies. Based on our experiments on speech data, we then numerically compute a universal frequencywarping function, to make the scale-factor independent of frequency in the warped domain. The proposed warping function is found to be similar to the mel-scale, wh...

This research reports on a system able to classify di€erent signals containing auditive information based on capture of small signal segments present in speci®c types of sound. After using a Haar wavelet transform at the preprocessing stage, a neural network known as the O-algorithm compares segments from candidate audio signals against prede®ned templates stored in the network. The classi®cati...

one of the challenging issues in managing the existing large digital image libraries and databases is content based image retrieval (cbir). the accuracy of image retrieval methods in cbir is subject to effective extraction of image features such as color, texture, and shape. in this paper, we propose a new image retrieval method using contourlet transform coefficients to index texture of the im...

As the useful time-frequency tool, the Fractional Fourier Transform (FRFT) and the Short Time Fourier Transform (STFT) have a great development of signal recognition. And the Reduced Fractional Fourier Transform (RFRFT) was recently proposed and has been used in the recognition and estimation of chirp signals. A new method based on STFT and RFRFT is presented for radar signals modulation recogn...