A new multistage Wiener filter is introduced which utilizes a decomposition based on orthogonal projections. A reduced-rank Wiener filter is developed based on this new structure which is not basis oriented, but evolv...
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A new multistage Wiener filter is introduced which utilizes a decomposition based on orthogonal projections. A reduced-rank Wiener filter is developed based on this new structure which is not basis oriented, but evolves a basis which is a function of the multistage decomposition. The performance of this new Wiener filtering structure is evaluated using a comparative computer analysis model. It is demonstrated that the low-complexity multistage reduced-rank Wiener filter is capable of outperforming the more complex eigendecomposition-based methods.
This correspondence presents a speech recognition system of speaker-independent Thai polysyllabic words. This development is based on the discrete hidden Markov model in conjunction with vector quantization algorithm,...
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This correspondence presents a speech recognition system of speaker-independent Thai polysyllabic words. This development is based on the discrete hidden Markov model in conjunction with vector quantization algorithm, endpoint detection algorithm for syllable endpoint detection and separation, and time normalization algorithm. The 70-Thai word vocabulary is subdivided into four sets comprising single, double, and triple syllabled words, 20 words in each set, and the last set consists of 10-Thai numeric words, zero to nine. The separated speech training set and testing set are composed of both male and female speakers within the range of 18 to 25 years old. For the tonal characteristics of the Thai language, the algorithms and the model parameters are modified in order to be applicable to the Thai language. The experiments on the effects of model parameter variations on recognition rate are conducted. The model parameters are number of codebooks, number of model states, and number of training speakers. The results show that the increase in the number of codebook and the number of model states have the major effect on the recognition rates. Also, the number of training speakers has less effect than the others. The average recognition rate of this speaker-independent recognition system is 89.906 percent for 40 speakers testing set using 256 vector codebook of 10-order linear prediction coefficients and 15-state model parameters. The recognition rate of the four sets of words are 86.750 percent for single-syllabled words, 92.375 percent for double-syllabled words, 96.250 percent for triple-syllabled words, and 84.250 percent for the numeric words.
From the transfer functions of an acousto-optic (AO) cell, it is found that some basic image processing can be accomplished by using AO cells. Instead of frequency-plane filters, the AO cells are placed directly behin...
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From the transfer functions of an acousto-optic (AO) cell, it is found that some basic image processing can be accomplished by using AO cells. Instead of frequency-plane filters, the AO cells are placed directly behind the object. The one dimensional edge enhancement results using one AO cell can be improved by using two acousto-optic cells which are put in tandem and with contra-propagating sound. The dominant second derivative operation obtained from the transfer function of the undiffracted order works like a one-dimensional Laplacian operator which enables improved edge enhancement.
This paper addresses the problem of automatic detection of burn-through in weld joints. Gas metal are (GMA) welding with pulsed current is used, and welding voltage and current are recorded. As short-circuitings are c...
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This paper addresses the problem of automatic detection of burn-through in weld joints. Gas metal are (GMA) welding with pulsed current is used, and welding voltage and current are recorded. As short-circuitings are common between the welding electrode and the work piece during burn-through, a short-circuit detector is developed to detect these events. To detect another specific characteristic of burn-through-a broadband long-lasting voltage component-this detector is combined with a square-law detector. This second detector is based on a non-linear modification of an autoregressive model with extra input (ARX-model) of the welding process. The results obtained from this compound detector indicate that it is possible to detect burn-through in the welds automatically. The work also indicates that it is possible to design an on-line monitoring system for robotic GMA welding. (C) 1996 Academic Press Limited
This paper deals with estimation of the waveform of a single event-related potential, sERP. An additive noise model is used for the measured signal and the SNR of the disturbed sERP is approximately 0 dB. The sERP is ...
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This paper deals with estimation of the waveform of a single event-related potential, sERP. An additive noise model is used for the measured signal and the SNR of the disturbed sERP is approximately 0 dB. The sERP is described by a series expansion where the basis functions are damped sinusoids. The fundamental basis function is estimated by the least squares Prony method, derived for colored noise. The performance of the Prony method for different forms of the power density spectrum of the noise is investigated. A white noise approximation can be used at low signal-to-noise (SNR). The basis functions change slowly but the waveform of the sERP may vary from one stimulus to another, thus we average a small number of correlation functions in order to increase the SNR. The method is evaluated by using measurements from four subjects and the results confirm the variability of the sERP.
The mainstream approach to subband coding has been to partition the input signal into subband signals and to code those signals separately with optimal or near-optimal quantizers and entropy coders. A more effective a...
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The mainstream approach to subband coding has been to partition the input signal into subband signals and to code those signals separately with optimal or near-optimal quantizers and entropy coders. A more effective approach, however, is one where subband coders are optimized jointly so that the average distortion introduced by the subband quantizers is minimized subject to a constraint on the output rate of the subband encoder. In this paper, a subband coder with jointly optimized multistage residual quantizers and entropy coders is introduced and applied to image coding. The high performance of the coder is attributed to its ability to exploit statistical dependencies within and across the subbands. The efficiency of the multistage residual quantization structure and the effectiveness of the statistical modeling algorithm result in an attractive balance among reproduction quality, rate, and complexity.
This paper introduces an extension of entropy-constrained residual vector quantization (VQ) where intervector dependencies are exploited, The method, which we call conditional entropy-constrained residual VQ, employs ...
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This paper introduces an extension of entropy-constrained residual vector quantization (VQ) where intervector dependencies are exploited, The method, which we call conditional entropy-constrained residual VQ, employs a high-order entropy conditioning strategy that captures local information in the neighboring vectors, When applied to coding images, the proposed method is shown to achieve better rate-distortion performance than that of entropy-constrained residual vector quantization with less computational complexity and lower memory requirements. Moreover, it can be designed to support progressive transmission in a natural way, It is also shown to outperform some of the best predictive and finite-state VQ techniques reported in the literature, This is due partly to the joint optimization between the residual vector quantizer and a high-order conditional entropy coder as well as the efficiency of the multistage residual VQ structure and the dynamic nature of the prediction.
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