In the study of brain-computer interfaces,a method of feature extraction and classification used fortwo kinds of imaginations is proposed.It considers Euclidean distance between mean traces recorded fromthe channels w...In the study of brain-computer interfaces,a method of feature extraction and classification used fortwo kinds of imaginations is proposed.It considers Euclidean distance between mean traces recorded fromthe channels with two kinds of imaginations as a feature,and determines imagination classes using thresh-old value.It analyzed the background of experiment and theoretical foundation referring to the data sets ofBCI 2003,and compared the classification precision with the best result of the competition.The resultshows that the method has a high precision and is advantageous for being applied to practical systems.展开更多
根据辽东半岛赤松(Pinus densiflora sieb et Zucc)群落对环境条件的响应,对赤松群落结构与多样性变量进行研究,有利于群落内功能特征从生态位分布空间上的功能分异度的研究向基于性状的研究转变。根据CFERN行业标准,在已经建立的动态...根据辽东半岛赤松(Pinus densiflora sieb et Zucc)群落对环境条件的响应,对赤松群落结构与多样性变量进行研究,有利于群落内功能特征从生态位分布空间上的功能分异度的研究向基于性状的研究转变。根据CFERN行业标准,在已经建立的动态监测指标体系基础上,通过功能距离和谱系结构在共有性状连续变化轴上的分类位置为依据,对辽东半岛赤松群落结构与功能等一系列变量进行分析。结果表明:赤松种群分布的同质性最强,可控制范围最大;蒙古栎在AⅢ波段后呈现出随龄级递增而周期振幅减小的变化趋势,群落总波序值均较小;群落内功能的覆盖度和耐受性可以用个体全距和移动全距来解释。得出结论,采用林龄和生长量降低性状的数量,可以预测具有功能的物种之间各林龄段的波序,证明能量流动和物质循环在各段的优势显著性;利用植物功能类型的变量,帮助我们理解生态服务的作用机制及各种服务之间的权衡关系,是一种必要的研究手段。展开更多
High precision of CFD code was used to study supercritical Airfoil RAE2822 superimposed with different shock control bumps under the transonic conditions.A successful improvement was made to current widely used Hicks-...High precision of CFD code was used to study supercritical Airfoil RAE2822 superimposed with different shock control bumps under the transonic conditions.A successful improvement was made to current widely used Hicks-Henne functions which describe shock control bumps.Based on improving the airfoil's lift-drag ratio,the study shows that,(1) the best bump crest position is at the position close to 50% of bump chord,which is almost independent of free stream or pre-shock Mach numbers,but the bump height is highly coupled with the crest position,which means that the higher the bump is,the more obviously the crest position affects the airfoil lift-drag ratio,and it becomes more evident with the increase of free stream or pre-shock Mach numbers;(2) in case that the lift-drag ratio of airfoil with bump is higher than basic airfoil,almost all the optimum distances between bump crest and shock wave are close to 30% of bump chord;(3) almost all the lift-drag ratios of airfoil with bump increase as bump chord length increases,of which this trend becomes more evident as bump height increases;(4) with the increase of the bump height,almost all the lift-drag ratios of airfoil with bump decrease at low free stream or pre-shock Mach numbers.When the Mach numbers are higher,the lift-drag ratio of airfoil increases as the increase of the bump height,and particularly,the trend tends to be visible when the Mach numbers are at a high level.展开更多
基金supported by the Shanghai Education Commission Foundation for Excellent Young High Education Teacher(No.sdj08001)
文摘In the study of brain-computer interfaces,a method of feature extraction and classification used fortwo kinds of imaginations is proposed.It considers Euclidean distance between mean traces recorded fromthe channels with two kinds of imaginations as a feature,and determines imagination classes using thresh-old value.It analyzed the background of experiment and theoretical foundation referring to the data sets ofBCI 2003,and compared the classification precision with the best result of the competition.The resultshows that the method has a high precision and is advantageous for being applied to practical systems.
文摘根据辽东半岛赤松(Pinus densiflora sieb et Zucc)群落对环境条件的响应,对赤松群落结构与多样性变量进行研究,有利于群落内功能特征从生态位分布空间上的功能分异度的研究向基于性状的研究转变。根据CFERN行业标准,在已经建立的动态监测指标体系基础上,通过功能距离和谱系结构在共有性状连续变化轴上的分类位置为依据,对辽东半岛赤松群落结构与功能等一系列变量进行分析。结果表明:赤松种群分布的同质性最强,可控制范围最大;蒙古栎在AⅢ波段后呈现出随龄级递增而周期振幅减小的变化趋势,群落总波序值均较小;群落内功能的覆盖度和耐受性可以用个体全距和移动全距来解释。得出结论,采用林龄和生长量降低性状的数量,可以预测具有功能的物种之间各林龄段的波序,证明能量流动和物质循环在各段的优势显著性;利用植物功能类型的变量,帮助我们理解生态服务的作用机制及各种服务之间的权衡关系,是一种必要的研究手段。
文摘High precision of CFD code was used to study supercritical Airfoil RAE2822 superimposed with different shock control bumps under the transonic conditions.A successful improvement was made to current widely used Hicks-Henne functions which describe shock control bumps.Based on improving the airfoil's lift-drag ratio,the study shows that,(1) the best bump crest position is at the position close to 50% of bump chord,which is almost independent of free stream or pre-shock Mach numbers,but the bump height is highly coupled with the crest position,which means that the higher the bump is,the more obviously the crest position affects the airfoil lift-drag ratio,and it becomes more evident with the increase of free stream or pre-shock Mach numbers;(2) in case that the lift-drag ratio of airfoil with bump is higher than basic airfoil,almost all the optimum distances between bump crest and shock wave are close to 30% of bump chord;(3) almost all the lift-drag ratios of airfoil with bump increase as bump chord length increases,of which this trend becomes more evident as bump height increases;(4) with the increase of the bump height,almost all the lift-drag ratios of airfoil with bump decrease at low free stream or pre-shock Mach numbers.When the Mach numbers are higher,the lift-drag ratio of airfoil increases as the increase of the bump height,and particularly,the trend tends to be visible when the Mach numbers are at a high level.
