目的建立同步检测畲药树参中紫丁香苷、绿原酸、芥子醛葡萄糖苷、松柏醇、芦丁、山柰酚-3-O-芸香糖苷、3,4-O-二咖啡酰基奎宁酸、3,5-O-二咖啡酰基奎宁酸和4,5-O-二咖啡酰基奎宁酸含量的高效液相色谱一测多评(HPLC-QAMS)方法,并采用多...目的建立同步检测畲药树参中紫丁香苷、绿原酸、芥子醛葡萄糖苷、松柏醇、芦丁、山柰酚-3-O-芸香糖苷、3,4-O-二咖啡酰基奎宁酸、3,5-O-二咖啡酰基奎宁酸和4,5-O-二咖啡酰基奎宁酸含量的高效液相色谱一测多评(HPLC-QAMS)方法,并采用多元统计分析及加权优劣解距离(technique for order preference by similarity to ideal solution method,TOPSIS)法对其品质进行综合评价。方法以Waters Xbridge C 18色谱柱;乙腈-0.05%甲酸溶液为流动相,梯度洗脱;检测波长260 nm。以山柰酚-3-O-芸香糖苷为参照物,建立内参物与其他8个待测成分的相对校正因子(relative correction factor,RCF),进行RCF耐用性考察及色谱峰定位,同时与外标法实测结果进行对比,验证HPLC-QAMS法准确性和可靠性。运用主成分分析(principal component analysis,PCA)、正交偏最小二乘法-判别分析(orthogonal partial least squares-discriminant analysis,OPLS-DA)等多元统计分析以及W-TOPSIS法对9个成分HPLC-QAMS法含量结果的相关性进行分析,挖掘影响畲药树参产品质量的主要潜在标志物,建立畲药树参综合质量优劣评价方法。结果9种成分分别在3.27~81.75μg/mL、9.85~246.25μg/mL、0.43~0.75μg/mL、0.31~7.75μg/mL、1.58~39.50μg/mL、0.59~14.75μg/mL、1.26~31.50μg/mL、4.55~113.75μg/mL和1.98~49.50μg/mL范围内线性关系良好,平均加样回收率96.82%~100.07%(RSD<2.0%);HPLC-QAMS和外标法(ESM)含量测定结果差异无统计学意义(P>0.05),HPLC-QAMS法可用于畲药树参多组分定量控制;多元统计分析结果显示,前2个主成分累计方差贡献率89.589%,绿原酸、紫丁香苷、3,5-O-二咖啡酰基奎宁酸和4,5-O-二咖啡酰基奎宁酸是影响畲药树参产品质量的主要潜在标志物;加权TOPSIS法结果显示浙江地区所得畲药树参质量最优,其次为江西、安徽、湖南和湖北产树参,云南和贵州产树参位于排名后4位。结论所建立的HPLC-QAMS多组分定量控制方法,操作便捷、结果准确;多元统计分析联合加权TOPSIS法全面客观,可用于畲药树参品质的综合评价。展开更多
Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inhe...Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inherent imaginary interference (IMI). This has an important impact on the channel estimation process. Currently, a variety of frequency-domain channel estimation methods have been proposed. However, there are various problems that still exist. For instance, in order to reduce the influence of IMI, it is necessary to insert more guard intervals between the training sequence and the payload, leading to the occupation of excessive spectrum resources. In order to address this problem, this work designs a high spectral efficient frequency-domain channel estimation method for the polarization-division-multiplexing CO-OFDM-OQAM systems. First, the working principle of the proposed method is described in detail. Then, its spectral efficiency, power peak-to-average ratio, and channel estimation performance are studied based on simulations. The simulation results show that the proposed method improves the spectral efficiency without worsening the power peak-to-average ratio. The channel estimation capability of this method is verified in three scenarios of long-distance transmissions, including back-to-back, 100 km, and 200 km transmissions. .展开更多
在多径衰落信道中,基于交错正交幅度调制的正交频分复用(OFDM with Offset QAM,OFDM/OQAM)系统使用迫零均衡器进行信号检测时,不能完全消除信道复数特性和滤波器实数正交特性引入的时域符号间干扰和频域子载波间干扰,及信道估计误差导...在多径衰落信道中,基于交错正交幅度调制的正交频分复用(OFDM with Offset QAM,OFDM/OQAM)系统使用迫零均衡器进行信号检测时,不能完全消除信道复数特性和滤波器实数正交特性引入的时域符号间干扰和频域子载波间干扰,及信道估计误差导致的误码率性能损失。该文利用对数据初始判决并重构相邻载波及符号间干扰的思想,通过分析采用迫零均衡信号检测时的残余干扰与信道估计误差干扰,提出了一种基于并行干扰抵消和迫零均衡器结合的OFDM/OQAM信号检测方法,并在IEEE 802.22技术标准的两种典型多径衰落信道中进行了计算机仿真与比较研究。仿真结果表明,与基于迫零均衡的检测方法相比,基于并行干扰抵消的迭代信号检测方法在误码率为1%时,可获得1 dB至2 dB的性能提升。展开更多
与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中...与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中的信道估计方法会导致OFDM/OQAM系统严重的字符间干扰和载波间干扰。该文结合OFDM/OQAM系统结构特点,提出了一种基于迭代信道估计和信号检测算法。该算法通过信道估计器和接收到的信号互相交换信息,消除导频序列中的字符间干扰和载波间干扰,提高信道估计和信号检测的准确度。仿真分析结果表明,经过一定次数迭代处理后,OFDM/OQAM迭代信道估计性能趋近于理想信道估计性能。展开更多
针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在...针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在载波频偏情况下OFDM/OQAM接收信号的二阶循环平稳特性,在此基础上,提出一种OFDM/OQAM系统载波频率偏差的盲估计算法。理论分析和仿真结果表明由该方法构造的估计器不仅能够有效地抵抗双选信道引起的衰落而且具有很好的抗噪性能,从而可以实现对载波频偏的稳健估计。展开更多
The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation o...The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.展开更多
针对电力线通信(PLC)正交频分复用(OFDM)系统存在频率掩码和频谱资源利用率低等问题,提出将正交频分复用/偏移正交幅度调制(OFDM/OQAM)技术应用到PLC系统中。该技术通过选用频率选择性较好的滤波器来抑制带外干扰,且不需要循环前缀,但是...针对电力线通信(PLC)正交频分复用(OFDM)系统存在频率掩码和频谱资源利用率低等问题,提出将正交频分复用/偏移正交幅度调制(OFDM/OQAM)技术应用到PLC系统中。该技术通过选用频率选择性较好的滤波器来抑制带外干扰,且不需要循环前缀,但是OFDM/OQAM系统在PLC频域复数信道下会产生严重的自干扰,传统的均衡算法并不能有效地消除OFDM/OQAM系统的固有干扰。针对这种情况提出了一种基于信道相位预处理的均衡算法。该算法的思想是让接收信号乘以一个信道相位调整因子,使等效信道的虚部尽量小,以此来减小接收信号中的干扰分量。仿真结果表明,与传统的均衡算法相比,所提算法在误比特率为1.0×10^(-6)时可以获得0.5 d B的性能提升。展开更多
文摘目的建立同步检测畲药树参中紫丁香苷、绿原酸、芥子醛葡萄糖苷、松柏醇、芦丁、山柰酚-3-O-芸香糖苷、3,4-O-二咖啡酰基奎宁酸、3,5-O-二咖啡酰基奎宁酸和4,5-O-二咖啡酰基奎宁酸含量的高效液相色谱一测多评(HPLC-QAMS)方法,并采用多元统计分析及加权优劣解距离(technique for order preference by similarity to ideal solution method,TOPSIS)法对其品质进行综合评价。方法以Waters Xbridge C 18色谱柱;乙腈-0.05%甲酸溶液为流动相,梯度洗脱;检测波长260 nm。以山柰酚-3-O-芸香糖苷为参照物,建立内参物与其他8个待测成分的相对校正因子(relative correction factor,RCF),进行RCF耐用性考察及色谱峰定位,同时与外标法实测结果进行对比,验证HPLC-QAMS法准确性和可靠性。运用主成分分析(principal component analysis,PCA)、正交偏最小二乘法-判别分析(orthogonal partial least squares-discriminant analysis,OPLS-DA)等多元统计分析以及W-TOPSIS法对9个成分HPLC-QAMS法含量结果的相关性进行分析,挖掘影响畲药树参产品质量的主要潜在标志物,建立畲药树参综合质量优劣评价方法。结果9种成分分别在3.27~81.75μg/mL、9.85~246.25μg/mL、0.43~0.75μg/mL、0.31~7.75μg/mL、1.58~39.50μg/mL、0.59~14.75μg/mL、1.26~31.50μg/mL、4.55~113.75μg/mL和1.98~49.50μg/mL范围内线性关系良好,平均加样回收率96.82%~100.07%(RSD<2.0%);HPLC-QAMS和外标法(ESM)含量测定结果差异无统计学意义(P>0.05),HPLC-QAMS法可用于畲药树参多组分定量控制;多元统计分析结果显示,前2个主成分累计方差贡献率89.589%,绿原酸、紫丁香苷、3,5-O-二咖啡酰基奎宁酸和4,5-O-二咖啡酰基奎宁酸是影响畲药树参产品质量的主要潜在标志物;加权TOPSIS法结果显示浙江地区所得畲药树参质量最优,其次为江西、安徽、湖南和湖北产树参,云南和贵州产树参位于排名后4位。结论所建立的HPLC-QAMS多组分定量控制方法,操作便捷、结果准确;多元统计分析联合加权TOPSIS法全面客观,可用于畲药树参品质的综合评价。
文摘Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inherent imaginary interference (IMI). This has an important impact on the channel estimation process. Currently, a variety of frequency-domain channel estimation methods have been proposed. However, there are various problems that still exist. For instance, in order to reduce the influence of IMI, it is necessary to insert more guard intervals between the training sequence and the payload, leading to the occupation of excessive spectrum resources. In order to address this problem, this work designs a high spectral efficient frequency-domain channel estimation method for the polarization-division-multiplexing CO-OFDM-OQAM systems. First, the working principle of the proposed method is described in detail. Then, its spectral efficiency, power peak-to-average ratio, and channel estimation performance are studied based on simulations. The simulation results show that the proposed method improves the spectral efficiency without worsening the power peak-to-average ratio. The channel estimation capability of this method is verified in three scenarios of long-distance transmissions, including back-to-back, 100 km, and 200 km transmissions. .
文摘与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中的信道估计方法会导致OFDM/OQAM系统严重的字符间干扰和载波间干扰。该文结合OFDM/OQAM系统结构特点,提出了一种基于迭代信道估计和信号检测算法。该算法通过信道估计器和接收到的信号互相交换信息,消除导频序列中的字符间干扰和载波间干扰,提高信道估计和信号检测的准确度。仿真分析结果表明,经过一定次数迭代处理后,OFDM/OQAM迭代信道估计性能趋近于理想信道估计性能。
文摘针对时频双选衰落信道下基于交错正交幅度调制的正交频分复用(orthogonal frequency division multiplexing with offset quadrature amplitude modulation,OFDM/OQAM)系统的频率同步问题,将双选信道建模为复指数基扩展模型,证明了存在载波频偏情况下OFDM/OQAM接收信号的二阶循环平稳特性,在此基础上,提出一种OFDM/OQAM系统载波频率偏差的盲估计算法。理论分析和仿真结果表明由该方法构造的估计器不仅能够有效地抵抗双选信道引起的衰落而且具有很好的抗噪性能,从而可以实现对载波频偏的稳健估计。
文摘The performance of an OFDM/OQAM system under phase noise is analyzed. The analysis helps to direct the design of low cost tuners through specifying the required phase noise characteristics. Discrete time formulation of OFDM/OQAM is first derived with the square root raised cosine (SRRC) filter as the pulse-shaping filter. Then the effect of multiplicative phase noise is equivalently represented as additive white Gaussian noise (AWGN), the variance of which is given analytically. We can observe that the same result as OFDM/QAM system is derived. Lastly, all the analytical results are verified by the bit error rate (BER) degradation through Monte Carlo simulation.
文摘针对电力线通信(PLC)正交频分复用(OFDM)系统存在频率掩码和频谱资源利用率低等问题,提出将正交频分复用/偏移正交幅度调制(OFDM/OQAM)技术应用到PLC系统中。该技术通过选用频率选择性较好的滤波器来抑制带外干扰,且不需要循环前缀,但是OFDM/OQAM系统在PLC频域复数信道下会产生严重的自干扰,传统的均衡算法并不能有效地消除OFDM/OQAM系统的固有干扰。针对这种情况提出了一种基于信道相位预处理的均衡算法。该算法的思想是让接收信号乘以一个信道相位调整因子,使等效信道的虚部尽量小,以此来减小接收信号中的干扰分量。仿真结果表明,与传统的均衡算法相比,所提算法在误比特率为1.0×10^(-6)时可以获得0.5 d B的性能提升。
