用气相色谱仪快速分析管道天然气成分

对天然气成分进行准确分析可有效提高计量的准确性。目前天然气的计量主要有两种方法：体积计量和能量计量。天然气各组分含量是天然气计量的基础参数,气相色谱法是测量天然气组成最常用的方法。气相色谱法具有选择性高、分离效率高、灵敏度高、分析速度快、应用范围广等特点。     

Enhanced fourth-power algorithm for phase estimation with frequency separation in direct-detection optical OFDM systems

The optical orthogonal frequency division multiplexing(OFDM) signal is affected by impairments introduced by electrical filters and optical chromatic dispersion.An enhanced fourth-power algorithm for phase estimation with frequency separation is used to estimate and compensate the phase rotation of OFDM subcarriers.The performance of the proposed phase estimation algorithm is evaluated on a 4-Gb/s OFDM signal at different frequencies.Experimental results using the proposed algorithm show a 1.8-dB received power sensitivity improvement at a bit error rate of 1×10-4 after a 100-km standard single-mode fiber transmission,compared with the conventional technique.