The wavelet transform is of good localization property in the domain of time and frequency, which provides a comprehensive application in processing acoustic wave.

小波变换同时有在时间域和频率域对信号进行局部化的特点，使其在声波信号处理中有着广泛的应用前景。

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Wavelet packet transform is used as an efficient tool for precisely analyzing signal property, and provides orthogonal wavelet packet bases with better time frequency localization function.

小波包变换能作为一种有效工具对信号特性进行精细分析，同时提供具有良好时频局部性的正交小波包基。

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Using high frequency intra - day data, we study the correlations between liquidity and trading activity and their time series property.

本文利用日内交易的高频分时数据，研究了流动性和交易活动之间的相关性和各自的时间序列性质。

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