This paper investigates the similarities between Gabor filters and the octave-band directional filter bank (OBDFB) with respect to texture classification. Both decompositions can angularly and radially discriminate in...
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This paper investigates the similarities between Gabor filters and the octave-band directional filter bank (OBDFB) with respect to texture classification. Both decompositions can angularly and radially discriminate in the 2-D frequency domain; however, the OB-DFB has a computationally efficient implementation that makes it an attractive alternative to Gabor filters. An analysis of local energy features from Gabor filters and the OBDFB is presented showing similarities between their texture features. Texture classification experiments using both decompositions show comparable classification accuracy.
A new method based on generalized likelihood ratio test (GLRT) for activation detection in multi-subject studies of functional MRI (fMRI) is proposed. In this method, we test the correlation between the fMRI time seri...
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A new method based on generalized likelihood ratio test (GLRT) for activation detection in multi-subject studies of functional MRI (fMRI) is proposed. In this method, we test the correlation between the fMRI time series of different subjects and the bases of a signal subspace which increases the flexibility of method in detecting different shapes of hemodynamic response. The proposed multivariate method can be applied to group studies where the conventional cross-correlation method cannot be used due to its univariate property. This method is applied to both experimental and simulated fMRI data and the results are compared to those of general linear model (GLM). We show that the proposed method detects more significant activated regions in analyzing experimental data and more true voxels in simulated data
This paper examines the problem of modelling and resynthesis of voiced song with the goal of improving the subjective performance quality. A set of methods is introduced based on the sinusoidal model for speech which ...
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This paper examines the problem of modelling and resynthesis of voiced song with the goal of improving the subjective performance quality. A set of methods is introduced based on the sinusoidal model for speech which enables precise modification of spectral characteristics as well as vibrato structure while maintaining the original speech quality and naturalness of the voice. Spectral characteristics are modified by modelling the formant structure with a set of asymmetric generalized Gaussians. Subjective tests were conducted which show that the proposed methods are effective in providing high quality modifications to vocal characteristics.
The increasing amount of music being stored in digital formats calls for increasingly more creative methods for music information retrieval. One subset of music retrieval methods relies on storing a melody in a pitch ...
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The increasing amount of music being stored in digital formats calls for increasingly more creative methods for music information retrieval. One subset of music retrieval methods relies on storing a melody in a pitch contour representation. Most often, this contour information is generated either from symbolic format (MIDI) or from raw audio after a pitch transcription step. We propose a method of extracting pitch contour information from musical audio without an intermediate transcription step by combining a musically-tuned constant Q transform with crosscorrelation. When tested on a database of 520 monophonic music recordings, our method generates pitch contours from raw audio data with up to 98% accuracy.
signal subspace methods in DOA estimation for wideband sources require preprocessing to find initial values which are close enough to the true values or to convert sensor outputs into desired forms. The preprocessing ...
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signal subspace methods in DOA estimation for wideband sources require preprocessing to find initial values which are close enough to the true values or to convert sensor outputs into desired forms. The preprocessing procedure should be carefully done lest it introduce some distortion. Failure to find proper initial values may prevent convergence of the estimator or cause biases in the estimator. The proposed method detects uncorrelated wideband sources using the signal subspace and the noise subspace of decomposed wideband signals. It does not require any initial values. The only preprocessing is narrowband decomposition of the sensor output which is very common in other wideband methods. computer simulation showed that the proposed method has less bias than and comparable variance to CSSM with small focusing errors.
Spectrum analysis of surface waves (SASW) is one of the most effective non-invasive methods for soil characterization. Surface waves travel in the medium along a free boundary and can be easily detected by using a tra...
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Spectrum analysis of surface waves (SASW) is one of the most effective non-invasive methods for soil characterization. Surface waves travel in the medium along a free boundary and can be easily detected by using a transducer placed on the free surface of the boundary. Traditional methods of SASW are two-station methods that use the phase information at two receivers to determine phase velocity as a function of frequency. Multi-station methods have also been developed by using a two-dimensional Fourier transform approach, but these methods exhibit poor resolution. We propose a new method based on vector processing of data obtained from an array of tri-axial sensors to produce a high resolution, multi-modal spectrum of the surface waves. These different modes can be identified and reconstructed in time domain, and then inverted to obtain the shear velocity profile of the subsurface.
The Georgia Tech Regional engineering Program (GTREP) was originally created to provide the opportunity for students in southeastern Georgia to earn a Georgia Tech undergraduate engineering degree without leaving the ...
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Delay-and-sum (DS) beam-forming is one of the basic beam-forming methods, and it is effective for both narrow- And wide-band sources. However, DS beam-forming exhibits high computational complexity. Recently, a fast m...
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The delay-sum beamformer (DSBF) is a space-time domain beamforming,method that performs coherent summation of sensor data. However, the computational complexity of finding the steered response over all angles is O(N 3...
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The delay-sum beamformer (DSBF) is a space-time domain beamforming,method that performs coherent summation of sensor data. However, the computational complexity of finding the steered response over all angles is O(N 3 ). In this paper, an O(N 2 log 2 N) space-time domain beamforming algorithm it is proposed. This fast algorithm does not require uniform sensor spacing. It is called Quadtree Beamformer (QBF) because it is based on the iterative subband spectral decomposition method that has been used in the Quadtree BackProjection SAR imaging algorithm. The QBF is implemented by recursively performing a spectral decomposition process over the space-time domain sensor array data. It also provides intermediate stage data that can be used for multi-angle multiresolution beamforming.
Multicarrier modulation has rapidly become common in both wireline and wireless high speed digital communications applications. However, the large dynamic range of a multicarrier signal causes problems at both the tra...
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Multicarrier modulation has rapidly become common in both wireline and wireless high speed digital communications applications. However, the large dynamic range of a multicarrier signal causes problems at both the transmitter and the receiver. Here, finite-field mathematics are examined as a means of controlling the signal's dynamic range. A framework for multicarrier modulation with finite-field transforms is constructed, and equivalence to certain maximum distance separable error-correcting codes is demonstrated. Implications on the assumed digital channel model caused by using finite-field mathematics in the transmitter and receiver are also discussed.
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