A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain c...A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain conditions is obtained. An error system around the steady state is studied further. Moreover, the condition for the state having no traffic jam is derived. A new control scheme is presented to suppress the traffic jam in the modified coupled map car-following model under the open boundary. A control signal including the velocity differences between the following and the considering vehicles, and between the preceding and the considering vehicles is used. The condition under which the traffic jam can be well suppressed is analysed. The results are compared with that presented by t^onishi et al. （the KKH model）. The simulation results show that the temporal behaviour obtained in our model is better than that in the KKH model. The simulation results are in good agreement with the theoretical analysis.展开更多
为了更准确地描述带有记忆效应的射频(RF)功放特性,基于传统的动态X参数模型,结合功放长期记忆效应以及短期记忆效应机理,提出一种新型动态X参数功放建模方法。新模型保留X参数模型的静态核函数,利用双记忆路径模型提取出表征记忆效应...为了更准确地描述带有记忆效应的射频(RF)功放特性,基于传统的动态X参数模型,结合功放长期记忆效应以及短期记忆效应机理,提出一种新型动态X参数功放建模方法。新模型保留X参数模型的静态核函数,利用双记忆路径模型提取出表征记忆效应的非线性函数,替换动态核函数。采用输出信号为幅度与频率双变量的新型反馈(FB)结构,引入时变频率变量而简化动态核函数为二维核函数。使用MW6S010N设计功放并建模,由仿真可知,新模型在单音大信号及码分多址(CDMA)信号激励下,均能正确表征功放特性,归一化均方误差(NMSE)较静态X参数模型、传统动态X参数模型以及前馈(FF)结构X参数模型分别减少8.0 d B、6.3 d B、2.5 d B。结果表明该模型能够更加准确拟合带有非线性记忆效应功率放大器的特性。展开更多
在水声通信中,信道的多径效应会造成严重的码间串扰(ISI),而现有的均衡算法在处理ISI问题时存在收敛速度慢、稳态误差大、算法复杂不易于硬件移植等问题,为此结合判决反馈均衡器结构前向均衡(FFE)与判决均衡结构(DFE),提出了一种基于反...在水声通信中,信道的多径效应会造成严重的码间串扰(ISI),而现有的均衡算法在处理ISI问题时存在收敛速度慢、稳态误差大、算法复杂不易于硬件移植等问题,为此结合判决反馈均衡器结构前向均衡(FFE)与判决均衡结构(DFE),提出了一种基于反余弦步长函数和三参数调整因子的变步长最小均方(LMS)算法。首先对三参数因子α、β、r进行算法仿真,优化算法性能,与固定步长LMS算法、基于修正反正切的变步长LMS算法以及基于双曲正割函数的变步长LMS算法的收敛性能和稳态误差进行仿真比较,结果显示:所提算法的收敛速度较固定步长LMS算法提高了57.9%,稳态误差下降5 d B;较双曲正割LMS算法和修正反正切LMS算法提高了26.3%和15.8%,并且算法的稳态误差下降了1~2 d B。最后,将算法移植于信号处理模块,进行水下实验,结果表明,水声信道造成的ISI经过均衡器后,信号得以恢复,能够实际克服多径效应造成的水声信道ISI问题。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11072117,10802042,and 60904068)the Natural Science Foundation of Zhejiang Province,China (Grant No.Y6100023)+1 种基金the Natural Science Foundation of Ningbo,China (Grant No.2009B21003)the K.C.Wong Magna Fund in Ningbo University,China
文摘A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain conditions is obtained. An error system around the steady state is studied further. Moreover, the condition for the state having no traffic jam is derived. A new control scheme is presented to suppress the traffic jam in the modified coupled map car-following model under the open boundary. A control signal including the velocity differences between the following and the considering vehicles, and between the preceding and the considering vehicles is used. The condition under which the traffic jam can be well suppressed is analysed. The results are compared with that presented by t^onishi et al. （the KKH model）. The simulation results show that the temporal behaviour obtained in our model is better than that in the KKH model. The simulation results are in good agreement with the theoretical analysis.
文摘为了更准确地描述带有记忆效应的射频(RF)功放特性,基于传统的动态X参数模型,结合功放长期记忆效应以及短期记忆效应机理,提出一种新型动态X参数功放建模方法。新模型保留X参数模型的静态核函数,利用双记忆路径模型提取出表征记忆效应的非线性函数,替换动态核函数。采用输出信号为幅度与频率双变量的新型反馈(FB)结构,引入时变频率变量而简化动态核函数为二维核函数。使用MW6S010N设计功放并建模,由仿真可知,新模型在单音大信号及码分多址(CDMA)信号激励下,均能正确表征功放特性,归一化均方误差(NMSE)较静态X参数模型、传统动态X参数模型以及前馈(FF)结构X参数模型分别减少8.0 d B、6.3 d B、2.5 d B。结果表明该模型能够更加准确拟合带有非线性记忆效应功率放大器的特性。
文摘在水声通信中,信道的多径效应会造成严重的码间串扰(ISI),而现有的均衡算法在处理ISI问题时存在收敛速度慢、稳态误差大、算法复杂不易于硬件移植等问题,为此结合判决反馈均衡器结构前向均衡(FFE)与判决均衡结构(DFE),提出了一种基于反余弦步长函数和三参数调整因子的变步长最小均方(LMS)算法。首先对三参数因子α、β、r进行算法仿真,优化算法性能,与固定步长LMS算法、基于修正反正切的变步长LMS算法以及基于双曲正割函数的变步长LMS算法的收敛性能和稳态误差进行仿真比较,结果显示:所提算法的收敛速度较固定步长LMS算法提高了57.9%,稳态误差下降5 d B;较双曲正割LMS算法和修正反正切LMS算法提高了26.3%和15.8%,并且算法的稳态误差下降了1~2 d B。最后,将算法移植于信号处理模块,进行水下实验,结果表明,水声信道造成的ISI经过均衡器后,信号得以恢复,能够实际克服多径效应造成的水声信道ISI问题。
