Based on the density functional theory,we calculate the dependence of the band structures of bilayer ziezaff-edzed grapnene nanonooons(BZGNRs)upon ribbon width,interlayer distance and stacking styles.Unlike monolayer ...Based on the density functional theory,we calculate the dependence of the band structures of bilayer ziezaff-edzed grapnene nanonooons(BZGNRs)upon ribbon width,interlayer distance and stacking styles.Unlike monolayer zigzag GNR,whose energy gap is always zero under different ribbon widths,the gap of BZGNR varies greathy with the ribbon width or the interlayer distance.The greatest gaps for AA-stacking and AB-stacking BZGNRs are about 0.22eV and 0.12eV,respectively,which implies that gap-tuning of AA-BZGNRs is more effective than that of AB-BZGNRs.These results present a way to tune the band structures of BZGNRs and also provide theoretical guidance for the fabrication of GNR-based piezoelectric devices.展开更多
以液压型风力发电机组为研究对象,针对低风速条件下液压型机组的最佳功率追踪和功率平滑多目标寻优控制问题进行研究。建立液压型风力发电机组逆系统模型,分析模型非线性形式,确定逆系统的解耦方法,利用逆系统的方法设计液压系统转矩控...以液压型风力发电机组为研究对象,针对低风速条件下液压型机组的最佳功率追踪和功率平滑多目标寻优控制问题进行研究。建立液压型风力发电机组逆系统模型,分析模型非线性形式,确定逆系统的解耦方法,利用逆系统的方法设计液压系统转矩控制器,实现最佳功率追踪控制。通过线性二次型最优控制方法,设计功率追踪与功率平滑的多目标优化控制器。依托30 k VA液压型风力发电机组实验台进行仿真和实验研究,验证了该方法的可行性。仿真和实验结果表明该方法具有较好的控制效果,在保证最佳功率追踪的同时实现了功率平滑控制。研究结果对液压型风力发电机组具有重要的理论意义和工程价值。展开更多
基金Supported by the China Postdoctoral Science Foundation(Nos 20090460145 and 201003009)the Fundamental Research Funds for the Central Universities(No 201012200053)+1 种基金the Science and Technology Program of Hunan Province of China(No 2010DFJ411)High Performance Computing Center of CSU.
文摘Based on the density functional theory,we calculate the dependence of the band structures of bilayer ziezaff-edzed grapnene nanonooons(BZGNRs)upon ribbon width,interlayer distance and stacking styles.Unlike monolayer zigzag GNR,whose energy gap is always zero under different ribbon widths,the gap of BZGNR varies greathy with the ribbon width or the interlayer distance.The greatest gaps for AA-stacking and AB-stacking BZGNRs are about 0.22eV and 0.12eV,respectively,which implies that gap-tuning of AA-BZGNRs is more effective than that of AB-BZGNRs.These results present a way to tune the band structures of BZGNRs and also provide theoretical guidance for the fabrication of GNR-based piezoelectric devices.
文摘以液压型风力发电机组为研究对象,针对低风速条件下液压型机组的最佳功率追踪和功率平滑多目标寻优控制问题进行研究。建立液压型风力发电机组逆系统模型,分析模型非线性形式,确定逆系统的解耦方法,利用逆系统的方法设计液压系统转矩控制器,实现最佳功率追踪控制。通过线性二次型最优控制方法,设计功率追踪与功率平滑的多目标优化控制器。依托30 k VA液压型风力发电机组实验台进行仿真和实验研究,验证了该方法的可行性。仿真和实验结果表明该方法具有较好的控制效果,在保证最佳功率追踪的同时实现了功率平滑控制。研究结果对液压型风力发电机组具有重要的理论意义和工程价值。
