基于FDM阵列技术的双通道语音增强方法

为了抑制小型语音通信设备中的方向性噪声干扰问题,提出一种双通道的语音增强算法.该方法基于一阶差分麦克风(first-order differential microphone, FDM)阵列,并结合单通道的谱增强技术,可以同时提取语音和噪声估计,并能够实时地修正噪声谱.与现有的双通道语音增强技术相比,该算法可以获得2~6 dB的输出信噪比增益,且计算量减少了2/3.仿真结果表明: 该方法有效地改善了算法的噪声消除性能,且更适用于实时的语音增强系统.     

Particle-Based Iterative Blind Receiver for Orthogonal Frequency- Division Multiplexing with Frequency Offset

Orthogonal frequency-division multiplexing （OFDM） systems are sensitive to carrier frequency offset （CFO） which introduces intercarder interference and significantly degrades system performance. This paper describes an iterative blind receiver consisting of a sequential Monte Carlo detector, a CFO estimator, and a compensator to reduce intercarrier interference. The framework is of low complexity due to the separation of tasks in a joint detection problem. In addition, the CFO estimator utilizes soft output of the sequential Monte Carlo detector, which reduces the information loss caused by hard decisions and can obtain the CFO estimate in only one OFDM symbol. Simulation results demonstrate the effectiveness of the algorithm.     

Blind Carrier Frequency Offset Estimation via Power Spectrum Analysis in MIMO OFDM Systems

As a generalization of orthogonal frequency-division multiplexing (OFDM) systems,multi-input multi-output (MIMO) OFDM systems are very sensitive to carrier frequency offset (CFO).This paper proposes a blind CFO estimation method based on power spectrum analysis,which has high bandwidth efficiency and is much less complex.This method can be used to estimate the residual CFO,which is less than half of the subcarrier spacing.The method uses a cosine cost function to get a closed-form CFO estimate.Simulation results illustrate that the method is effective for MIMO OFDM systems.     

A Novel Minimum Output Variance Estimator for Carrier Frequency Offset in OFDM Systems

In orthogonal frequency-division multiplexing (OFDM) systems, the carrier frequency offset (CFO) destroys the orthogonality among subcarriers which degrades system performance. Various CFO estimation methods have been developed to compensate for the CFO at the receiver. This paper describes a novel minimum output variance method for OFDM systems with CFO in additive white Gaussian noise channels. This method utilizes the phase and the amplitude of the received signal and reduces the mean square error of the CFO by about 3 dB compared with the original minimum output variance method.     

中药中有机酸成分快速甲酯化方法的研究

以中药材猫爪草为分析对象,研究了简便快速分析中药中有机酸成分的方法。方法以10%硫酸甲醇-苯(1∶1)溶液为甲酯化试剂,利用微波辅助直接甲酯化药材,在微波功率600W、压力0.2MPa的条件下,反应1min即完成对药材中有机酸的甲酯化;采用气相色谱-质谱(GC-MS)联用技术进行分析,检出有23个色谱峰;经NIST2000标准谱库检索,识别了18种有机酸(占总峰面积的96.79%),并用对照品进行了验证。对不同来源的猫爪草药材进行分析,检出有20个共有峰,经方法学验证,符合指纹图谱的检测要求。     

HSGC-MSD及HSGC法鉴别草豆蔻真伪品

草豆蔻为姜科(Zingiberaceae)植物草豆蔻Alpinia katsumadai Hayata干燥成熟种子团.同属植物草豆蔻伪品长柄山姜Alpinia kwangsiensis T.L.Wu et Senjen的干燥种子团(民间代山姜).两者外形极易混淆,本文根据二者气味差异,试用顶空气相色谱(HSGC)及其顶空气相色谱-质谱(HSGC-MS)法对其进行了鉴别.