scholarly journals A Novel Subband Fractional Delay Algorithm Based on the Filterbank of Cochlear Implant

2020 ◽  
Author(s):  
Yousheng Chen ◽  
Yan Chen
Keyword(s):  
Cochlear Implant ◽  
Frequency Band ◽  
Filter Bank ◽  
Microphone Array ◽  
Average Error ◽  
System Response ◽  
Sampling Point ◽  
Sampling Points ◽  
Fractional Delay ◽  
Fractional Delay Filter

Abstract Background: In recent years, microphone array method is gradually applied to speech enhancement of cochlear implant, and the delay parameter is the main parameter of microphone array beamforming technology. Due to the size limitation of cochlear implant, the microphone spacing is very small. In algorithm implementation, delay parameter usually corresponds to fractional sampling point. It is necessary to use fractional delay filter to realize the interpolation of integer sampling points. The traditional fractional delay method is to interpolate sampling points in the whole frequency band of speech. However, the speech frequency band itself is very wide, so the error of the present fractional delay method in cochlear is still large. Methods: We propose a fractional delay algorithm based on the filter bank of cochlear implant. The algorithm deduces and calculates the mathematical expression of the fractional delay filter of each subband, and forms a full band fractional delay filter algorithm to minimize the delay error of the whole band. Realization and results: Through the analysis of the system response curve and the calculation of the delay error, it can be seen that the system response corresponding to the fractional delay of each subband in the cochlear filter bank has only a small deviation from the ideal fractional delay filter. Therefore, the error of the fractional delay filter designed in this paper is very small, which can meet the requirements of cochlear implant using microphone array technology for the precision of delay parameters. Discussions: In this paper, the implementation algorithm of subband fractional delay filter is applied to signal acquisition of cochlear implant. Considering the space condition and delay parameters in the actual application scenario, the value of fractional delay can be any continuous real number between 0 and 3, and the error situation of the algorithm can be calculated and analyzed in this range. If the algorithm is extended to other applications, the numerical range of fractional delay can be extended. From the statistics of the average error, it can be seen that the average error of the proposed algorithm in the whole frequency band is extremely small, which can meet the needs of the accuracy of the delay parameters in the application of cochlear implant. Conclusions: The proposed fractional delay filter based on the minimum subband error of cochlear implant can not only realize the local fractional delay minimization, but also the error minimization of the whole frequency band.

scholarly journals Behavioral Parameters of Planarians (Girardia tigrina) as Fast Screening, Integrative and Cumulative Biomarkers of Environmental Contamination: Preliminary Results

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1077
Author(s):  
Ana M. Córdova López ◽  
Althiéris de Souza Saraiva ◽  
Carlos Gravato ◽  
Amadeu M. V. M. Soares ◽  
Renato Almeida Sarmento
Keyword(s):  
Water Samples ◽  
Feeding Rate ◽  
Anthropogenic Activities ◽  
Behavioral Responses ◽  
Freshwater Ecosystems ◽  
Sampling Point ◽  
Total Chloride ◽  
Fast Screening ◽  
Sampling Points ◽  
The Impact

The present study aims to use behavioral responses of the freshwater planarian Girardia tigrina to assess the impact of anthropogenic activities on the aquatic ecosystem of the watershed Araguaia-Tocantins (Tocantins, Brazil). Behavioral responses are integrative and cumulative tools that reflect changes in energy allocation in organisms. Thus, feeding rate and locomotion velocity (pLMV) were determined to assess the effects induced by the laboratory exposure of adult planarians to water samples collected in the region of Tocantins-Araguaia, identifying the sampling points affected by contaminants. Furthermore, physicochemical and microbiological parameters, as well as the presence of inorganic compounds (dissolved aluminum, total barium, total chloride, dissolved iron, total fluoride, total manganese, nitrates, nitric nitrogen, total sulfate, total zinc) and surfactants, were determined on each specific sampling point. The behavioral biomarkers (feeding rate and pLMV) of the freshwater planarians were significantly decreased when organisms were exposed to water samples from four municipalities (Formoso do Araguaia, Lagoa da Confusão, Gurupi and Porto Nacional), sites of the Tocantins-Araguaia hydrographic region—TAHR. Both behavioral biomarkers decreased up to ~37–39% compared to organisms in ASTM medium only. Our results showed that these behavioral biomarkers can be used for fast screening monitoring of environmental samples of freshwater ecosystems, since a decrease in feeding rate and locomotor activity was observed in sites impacted by anthropogenic activities. However, the absence of effects observed in some sampling points does not represent the absence of contamination, since several other classes of contaminants were not determined. In these negative results, the absence of deleterious effects on behavioral biomarkers might only be indicative that the potential presence of contaminants on such sites does not significantly affect the performance of planarians. This fast screening approach seems to be useful to determine contaminated sites in freshwater ecosystems for biomonitoring purposes. This knowledge will help to develop biomonitoring programs and to decide appropriate sampling sites and analysis.

scholarly journals A Kriging-Assisted Multi-Objective Constrained Global Optimization Method for Expensive Black-Box Functions

Mathematics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 149
Author(s):  
Yaohui Li ◽  
Jingfang Shen ◽  
Ziliang Cai ◽  
Yizhong Wu ◽  
Shuting Wang
Keyword(s):  
Global Optimization ◽  
Pareto Frontier ◽  
Kriging Model ◽  
Optimization Method ◽  
Function Evaluation ◽  
Sampling Point ◽  
Constrained Global Optimization ◽  
Multi Objective ◽  
Sample Data ◽  
Sampling Points

The kriging optimization method that can only obtain one sampling point per cycle has encountered a bottleneck in practical engineering applications. How to find a suitable optimization method to generate multiple sampling points at a time while improving the accuracy of convergence and reducing the number of expensive evaluations has been a wide concern. For this reason, a kriging-assisted multi-objective constrained global optimization (KMCGO) method has been proposed. The sample data obtained from the expensive function evaluation is first used to construct or update the kriging model in each cycle. Then, kriging-based estimated target, RMSE (root mean square error), and feasibility probability are used to form three objectives, which are optimized to generate the Pareto frontier set through multi-objective optimization. Finally, the sample data from the Pareto frontier set is further screened to obtain more promising and valuable sampling points. The test results of five benchmark functions, four design problems, and a fuel economy simulation optimization prove the effectiveness of the proposed algorithm.

Structural Analysis by the Differential Quadrature Method Using Modified Weighting Matrices

1998 ◽  
Author(s):  
Siu-Tong Choi ◽  
Yu-Tuan Chou
Keyword(s):  
Boundary Conditions ◽  
Differential Quadrature Method ◽  
Differential Quadrature ◽  
Sampling Point ◽  
Order Partial Differential Equation ◽  
Quadrature Method ◽  
The Finite Element Method ◽  
Computationally Efficient ◽  
Base Points ◽  
Sampling Points

Abstract The differential quadrature method has lately been more and more often used for analysis of engineering problems as an alternative for the finite element method or finite difference method. In this paper, static, dynamic and buckling analyses of structural components are performed by the differential quadrature method. To improve the accuracy of this method, an approach is proposed for selecting the sampling points which include base points and conditional points. The base points are taken as the roots of the Legendre polynomials. Accuracy of the problems analyzed will be increased by using the base points. The conditional points are determined according to boundary conditions and specified conditions of external load. A modified algorithm is proposed for applying two or more boundary conditions in a sampling point at boundary of domain, such that the higher-order partial differential equation can be solved without adding new sampling points. By applying this approach to variety problems, such as deflections of beam under nonuniformly distributed loading, vibration and buckling analyses of beam and plate, it is found that numerical results of the present approach are more accurate than those obtained by the equally-spaced differential quadrature method and is computationally efficient.

scholarly journals Design of Variable Fractional Delay Filter using FIR Filter Approximation

2019 ◽  
Vol 8 (4) ◽  
pp. 5932-5936
Keyword(s):  
Interpolation Method ◽  
Fir Filter ◽  
Beam Forming ◽  
Rf Signals ◽  
Direct Form ◽  
Fractional Delay ◽  
Filter Approximation ◽  
Fractional Delay Filter ◽  
Is Design

Beamforming plays an important role in the field of wireless communication. Beamforming means combination of a radio frequency (RF) signals from multiple antennas to form a single direction beam. This technique improves the quality of communication and reduces the interference of signal. In beam forming technique, different phases signals can be achieved with different signals and the received phase delay signals are converted into same phase, multiply with weight factor and combined this signals to form a beam in desired direction. The required phase delays are generated by using a Variable fractional delay filter. Variable fractional delay filter is design by using a direct form of a FIR filter structure. Variable fractional delay filter is calculated by two different phase signals from digital antennas and those two different phase signals are converted to in- phase and added together to form a beam forming. As the order of the filter increases, the delay also increases. The filter coefficients of the variable fractional delay filter are calculated my using a Lagrange interpolation method. The variable fractional delay filter is designed by using software Xilinx version 14.3

Variable Ratio Sample Rate Conversion Based on Fractional Delay Filter

2015 ◽  
Vol 39 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Marek Blok ◽  
Piotr Drózda
Keyword(s):  
Speech Signal Processing ◽  
Farrow Structure ◽  
Conversion Algorithm ◽  
Window Method ◽  
Voiced Speech ◽  
Fractional Delay ◽  
Sample Rate ◽  
Fractional Delay Filter ◽  
Speech Segments ◽  
Rate Conversion

Abstract In this paper a sample rate conversion algorithm which allows for continuously changing resampling ratio has been presented. The proposed implementation is based on a variable fractional delay filter which is implemented by means of a Farrow structure. Coefficients of this structure are computed on the basis of fractional delay filters which are designed using the offset window method. The proposed approach allows us to freely change the instantaneous resampling ratio during processing. Using such an algorithm we can simulate recording of audio on magnetic tape with nonuniform velocity as well as remove such distortions. We have demonstrated capabilities of the proposed approach based on the example of speech signal processing with a resampling ratio which was computed on the basis of estimated fundamental frequency of voiced speech segments.

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