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find Keyword "信号处理" 4 results
  • A Modified Speech Enhancement Algorithm for Electronic Cochlear Implant and Its Digital Signal Processing Realization

    In order to improve the speech quality and auditory perceptiveness of electronic cochlear implant under strong noise background, a speech enhancement system used for electronic cochlear implant front-end was constructed. Taking digital signal processing (DSP) as the core, the system combines its multi-channel buffered serial port (McBSP) data transmission channel with extended audio interface chip TLV320AIC10, so speech signal acquisition and output with high speed are realized. Meanwhile, due to the traditional speech enhancement method which has the problems as bad adaptability, slow convergence speed and big steady-state error, versiera function and de-correlation principle were used to improve the existing adaptive filtering algorithm, which effectively enhanced the quality of voice communications. Test results verified the stability of the system and the de-noising performance of the algorithm, and it also proved that they could provide clearer speech signals for the deaf or tinnitus patients.

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  • Design of magneto-acoustic-electrical detection system and verification of its linear sweep theory

    Clinical studies had demonstrated that early diagnosis of lesion could significantly reduce the risk of cancer. Magneto-acoustic-electrical tomography (MAET) is expected to become a new detection method due to its advantages of high resolution and high contrast. Based on thinking of modular design, a low-cost, digital magneto-acoustic conductivity detection system was designed and implemented in this study. The theory of MAET using chirp continuous wave excitation was introduced. The results of homogeneous phantom experiment with 0.5% NaCl clearly showed that the conductivity curve of homogeneous phantom was highly consistent with the actual physical size, which indicated that the chirp excitation theory in our proposed system was correct and feasible. Besides, the resolution obtained by 1 000 μs sweep time was better than that obtained by 500 μs and 1 500 μs, which means that sweep time is an important factor affecting the detection resolution of the conductivity. The same result was obtained in the experiments carried out on homogeneous phantoms with different concentrations of NaCl, which demonstrated the repeatability of our proposed MAET system.

    Release date:2018-02-26 09:34 Export PDF Favorites Scan
  • 癫痫网络的定义:立体脑电图和信号分析的贡献

    致痫网络定义为癫痫放电产生和传播过程中累及的脑区。基于颅内电极电生理数据的分析,文章综述介绍了致痫网络的历史、方法和概念。在癫痫术前评估中,确定产生癫痫发作的脑区(如致痫区)是最重要的目标。较药物难治性局灶性癫痫传统的、局限性的视觉分析方法而言,致痫网络作为一个模型已逐渐得到公认。该模型能更好地描述发作动态演变的复杂性、更真实地描述大脑致痫性的异常分布。致痫网络概念在历史上与立体脑电图(SEEG)方法学的发展及随后脑电信号定量分析相关。SEEG 有明确的发作期、发作前及发作间期放电模式,可以用信号分析方法对上述模式进行分析,如高频振荡定量分析或分析功能连接的改变。我们可以在皮层和皮层下脑区癫痫发生和传播的过程中,依据 SEEG 数据分析得到大脑连接的显著变化,这些变化与不同的发作症状学模式相关。发作间期特征就是致痫网络产生异常电活动(发作间期棘波)及功能连接的改变。致痫网络大尺度建模新方法的引入为更好地预测手术预后提供了新方法。就明确致痫性脑区的分布而言,致痫网络的概念是一个关键的要素,这对癫痫手术尤为重要。

    Release date:2018-03-20 04:09 Export PDF Favorites Scan
  • Precise measurement of human heart rate based on multi-channel radar data fusion

    To achieve non-contact measurement of human heart rate and improve its accuracy, this paper proposes a method for measuring human heart rate based on multi-channel radar data fusion. The radar data were firstly extracted by human body position identification, phase extraction and unwinding, phase difference, band-pass filtering optimized by power spectrum entropy, and fast independent component analysis for each channel data. After overlaying and fusing the four-channel data, the heartbeat signal was separated using frost-optimized variational modal decomposition. Finally, a chirp Z-transform was introduced for heart rate estimation. After validation with 40 sets of data, the average root mean square error of the proposed method was 2.35 beats per minute, with an average error rate of 2.39%, a Pearson correlation coefficient of 0.97, a confidence interval of [–4.78, 4.78] beats per minute, and a consistency error of –0.04. The experimental results show that the proposed measurement method performs well in terms of accuracy, correlation, and consistency, enabling precise measurement of human heart rate.

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