The formation origin of two peaks in micellar electrokinetic capillary chromatography by using cetyltrimethylaminium bromide (or sodium dodecyl sulfate) as pseudo stationary phase is studied. It is pointed out that tw...The formation origin of two peaks in micellar electrokinetic capillary chromatography by using cetyltrimethylaminium bromide (or sodium dodecyl sulfate) as pseudo stationary phase is studied. It is pointed out that two peaks may appear for one component in certain conditions. Experiments show that the relative areas of the two peaks of the corresponding component depend on the time and temperature of reaction between the analyte and the surfactant, and the concentration of surfactant in the sample solution. One of the two peaks increase with the increase of surfactant concentration in the sample solution while reverse for another peak. Temperature can accelerate the reaction process. This means that the interaction between analyte and surfactant is a slow process, and a stable substance can be produced from the interaction and leads to the formation of two peaks. The standpoint is confirmed by the infrared and nuclear magnetic resonance spectra of the product from the reaction between cetyltrimethylaminium bromide and m-hydroxyl benzoic acid.展开更多
风电场配置电池储能系统(Battery Energy Storage System,BESS)是提高风电场调度计划精确度的有效手段。为提高风储联合发电系统跟踪调度计划出力能力、增加BESS收益,文章提出了一种基于模型预测控制(Model Predictive Control,MPC)和...风电场配置电池储能系统(Battery Energy Storage System,BESS)是提高风电场调度计划精确度的有效手段。为提高风储联合发电系统跟踪调度计划出力能力、增加BESS收益,文章提出了一种基于模型预测控制(Model Predictive Control,MPC)和双层模糊控制的BESS跟踪风电计划出力控制策略。首先,基于MPC方法建立了以并网功率与计划出力偏差、储能系统剩余容量偏离理想值最小为目标;其次,结合BESS实时荷电状态(State of Charge,SOC)与风电功率计划值动态跟踪需求,通过引入第一层模糊控制规则,实时调整目标函数中的权重系数,以获得最佳跟踪效果。同时,为提高BESS收益,结合SOC和峰谷分时电价,采用第二层模糊控制规则,对BESS的充放电功率进行修正;最后,在风储联合发电系统实验平台上对所提控制策略进行了验证,仿真结果表明,与传统MPC方法相比,所提控制策略提高了风储系统跟踪计划出力能力,避免了BESS越限,具有良好的峰谷套利收益。展开更多
传统聚类算法进行混叠矩阵估计时存在的聚类中心个数不确定和初始聚类中心的随机选取导致陷入局部最优的问题,为此提出一种基于密度峰值的改进模糊聚类算法进行欠定盲源分离的混叠矩阵估计。通过短时傅里叶变换提取信号在频域中的稀疏特...传统聚类算法进行混叠矩阵估计时存在的聚类中心个数不确定和初始聚类中心的随机选取导致陷入局部最优的问题,为此提出一种基于密度峰值的改进模糊聚类算法进行欠定盲源分离的混叠矩阵估计。通过短时傅里叶变换提取信号在频域中的稀疏特性,利用寻找密度峰值聚类算法(clustering by fast search and find of density peaks,CFSFDP)自动获取聚类簇的数目和初始聚类中心;将获得的聚类数目和聚类结果作为模糊聚类算法(fuzzy c-means clustering,FCM)的初始输入参数,提高FCM聚类结果的精度。实验结果表明,该算法可以准确估计源信号的数目,相比传统FCM、层次聚类、基于密度峰值改进的粒子群等聚类算法,可以有效提高欠定盲源分离的混叠矩阵估计精度。展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.20075005) the Natural Science Foundation of Hebei Province,China(Grant Nos.200077 and 202096).
文摘The formation origin of two peaks in micellar electrokinetic capillary chromatography by using cetyltrimethylaminium bromide (or sodium dodecyl sulfate) as pseudo stationary phase is studied. It is pointed out that two peaks may appear for one component in certain conditions. Experiments show that the relative areas of the two peaks of the corresponding component depend on the time and temperature of reaction between the analyte and the surfactant, and the concentration of surfactant in the sample solution. One of the two peaks increase with the increase of surfactant concentration in the sample solution while reverse for another peak. Temperature can accelerate the reaction process. This means that the interaction between analyte and surfactant is a slow process, and a stable substance can be produced from the interaction and leads to the formation of two peaks. The standpoint is confirmed by the infrared and nuclear magnetic resonance spectra of the product from the reaction between cetyltrimethylaminium bromide and m-hydroxyl benzoic acid.
文摘风电场配置电池储能系统(Battery Energy Storage System,BESS)是提高风电场调度计划精确度的有效手段。为提高风储联合发电系统跟踪调度计划出力能力、增加BESS收益,文章提出了一种基于模型预测控制(Model Predictive Control,MPC)和双层模糊控制的BESS跟踪风电计划出力控制策略。首先,基于MPC方法建立了以并网功率与计划出力偏差、储能系统剩余容量偏离理想值最小为目标;其次,结合BESS实时荷电状态(State of Charge,SOC)与风电功率计划值动态跟踪需求,通过引入第一层模糊控制规则,实时调整目标函数中的权重系数,以获得最佳跟踪效果。同时,为提高BESS收益,结合SOC和峰谷分时电价,采用第二层模糊控制规则,对BESS的充放电功率进行修正;最后,在风储联合发电系统实验平台上对所提控制策略进行了验证,仿真结果表明,与传统MPC方法相比,所提控制策略提高了风储系统跟踪计划出力能力,避免了BESS越限,具有良好的峰谷套利收益。
文摘传统聚类算法进行混叠矩阵估计时存在的聚类中心个数不确定和初始聚类中心的随机选取导致陷入局部最优的问题,为此提出一种基于密度峰值的改进模糊聚类算法进行欠定盲源分离的混叠矩阵估计。通过短时傅里叶变换提取信号在频域中的稀疏特性,利用寻找密度峰值聚类算法(clustering by fast search and find of density peaks,CFSFDP)自动获取聚类簇的数目和初始聚类中心;将获得的聚类数目和聚类结果作为模糊聚类算法(fuzzy c-means clustering,FCM)的初始输入参数,提高FCM聚类结果的精度。实验结果表明,该算法可以准确估计源信号的数目,相比传统FCM、层次聚类、基于密度峰值改进的粒子群等聚类算法,可以有效提高欠定盲源分离的混叠矩阵估计精度。
