Two Poisson brackets for the N-component coupled nonlinear Schrdinger(NLS) equation are derived by using the variantional principle. The first one is called the equal-time Poisson bracket which does not depend on time...Two Poisson brackets for the N-component coupled nonlinear Schrdinger(NLS) equation are derived by using the variantional principle. The first one is called the equal-time Poisson bracket which does not depend on time but only on the space variable. Actually it is just the usual one describing the time evolution of system in the traditional theory of integrable Hamiltonian systems. The second one is equal-space and new. It is shown that the spatial part of Lax pair with respect to the equal-time Poisson bracket and temporal part of Lax pair with respect to the equal-space Poisson bracket share the same r-matrix formulation. These properties are similar to that of the NLS equation.展开更多
We investigate quantum kinetic theory for a massive fermion system under a rotational field.From theDirac equation in rotating frame we derive the complete set of kinetic equations for the spin components of the 8-and...We investigate quantum kinetic theory for a massive fermion system under a rotational field.From theDirac equation in rotating frame we derive the complete set of kinetic equations for the spin components of the 8-and 7-dimensional Wigner functions.While the particles are no longer on a mass shell in the general case due to therotation-spin coupling,there are always only two independent components,which can be taken as the number andspin densities.With help from the off-shell constraint we obtain the closed transport equations for the two independent components in the classical limit and at the quantum level.The classical rotation-orbital coupling controls thedynamical evolution of the number density,but the quantum rotation-spin coupling explicitly changes the spin density.展开更多
水声通信作为海洋信息传输的核心技术,广泛应用于海洋探测、海事监管及海底工程等领域。然而,水声信道因双重色散特性而极具挑战性,对系统设计构成重大障碍。尽管正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)技术...水声通信作为海洋信息传输的核心技术,广泛应用于海洋探测、海事监管及海底工程等领域。然而,水声信道因双重色散特性而极具挑战性,对系统设计构成重大障碍。尽管正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)技术已在水声通信中得到广泛应用,但其性能仍受限于信道状态估计的准确性。正交时频空(Orthogonal Time Frequency Space, OTFS)调制技术通过将数据转换到时延-多普勒域内传输,能够有效地应对水声信道中的多径效应和多普勒频移,提高通信系统的性能和可靠性。综述了OTFS在水声通信中的关键处理技术,涵盖信道估计、信道均衡及多址接入技术三个核心方面,并从天线拓展、机器学习融合及同步创新等方面探讨了未来发展趋势,同时详细分析了复杂信道环境下的信号检测、计算复杂度与实时性平衡、参数估计准确性及水下环境对数据可靠性的影响面临的技术挑战。展开更多
随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time l...随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time linear equalizer,CTLE),该均衡器采用2级级联结构来补偿信道衰减,并提高接收信号的质量。此外,自适应模块通过采用符号-符号最小均方误差(sign-sign least mean square,SS-LMS)算法,使抽头系数加快了收敛速度。仿真结果表明,当传输速率为16 Gbit/s时,均衡器可以补偿-15.53 dB的半波特率通道衰减,均衡器系数在16×10^(4)个单元间隔数据内收敛,并且收敛之后接收误码率低于10^(-12)。展开更多
在高速SerDes系统中,随着数据传输速率越来越高,信道对数据高频分量的衰减越来越严重。为解决传统连续时间线性均衡器(Continuous Time Linear Equalizer,CTLE)高频补偿能力欠缺和无法适应不同信道衰减的问题,该文在传统CTLE的基础上,...在高速SerDes系统中,随着数据传输速率越来越高,信道对数据高频分量的衰减越来越严重。为解决传统连续时间线性均衡器(Continuous Time Linear Equalizer,CTLE)高频补偿能力欠缺和无法适应不同信道衰减的问题,该文在传统CTLE的基础上,级联低频均衡器,该均衡器采用双路源极负反馈电阻电容差分结构,对低频信号实现补偿的同时,通过源极负反馈电阻和电容引入了一对零极点,可实现对高频信号的二次补偿;同时,该CTLE的源极负反馈电阻电容可调,可实现零极点位置改变,产生不同的增益补偿,达到适应不同信道衰减的目的。在TSMC 28 nm CMOS工艺下,该CTLE在数据传输速率12.5 Gbps下高频补偿最高达20.5 dB,均衡范围为15.4~20.5 dB,眼图的平均张开度可达到0.92 UI。展开更多
常规的精密单点定位(Precise Point Positioning,PPP)算法中尚未考虑附加先验信息约束的方法,当系统存在固有的先验信息时,不加以利用可能会导致信息的浪费。对此,本文重点研究了车辆直线运动轨迹所存在的约束信息,推导整理了空间直线...常规的精密单点定位(Precise Point Positioning,PPP)算法中尚未考虑附加先验信息约束的方法,当系统存在固有的先验信息时,不加以利用可能会导致信息的浪费。对此,本文重点研究了车辆直线运动轨迹所存在的约束信息,推导整理了空间直线斜截式约束方程,同时结合等式约束滤波方法中的准确测量法应用到PPP的参数估计过程中,形成附加直线轨迹约束的PPP方法。实验表明:在铁路直线轨道约束实验中,收敛时间最高减少60%,定位精度最高提升14.94%,不同实验结果均表明附加直线轨迹约束能提高PPP定位性能。展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.11271168 and 11671177by the Priority Academic Program Development of Jiangsu Higher Education Institutionsby Innovation Project of the Graduate Students in Jiangsu Normal University
文摘Two Poisson brackets for the N-component coupled nonlinear Schrdinger(NLS) equation are derived by using the variantional principle. The first one is called the equal-time Poisson bracket which does not depend on time but only on the space variable. Actually it is just the usual one describing the time evolution of system in the traditional theory of integrable Hamiltonian systems. The second one is equal-space and new. It is shown that the spatial part of Lax pair with respect to the equal-time Poisson bracket and temporal part of Lax pair with respect to the equal-space Poisson bracket share the same r-matrix formulation. These properties are similar to that of the NLS equation.
基金Supported by Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008)NSFC (11890712, 12005112, 12075129)Supported by the Postdoctoral Innovative Talent Support Program of Tsinghua University
文摘We investigate quantum kinetic theory for a massive fermion system under a rotational field.From theDirac equation in rotating frame we derive the complete set of kinetic equations for the spin components of the 8-and 7-dimensional Wigner functions.While the particles are no longer on a mass shell in the general case due to therotation-spin coupling,there are always only two independent components,which can be taken as the number andspin densities.With help from the off-shell constraint we obtain the closed transport equations for the two independent components in the classical limit and at the quantum level.The classical rotation-orbital coupling controls thedynamical evolution of the number density,but the quantum rotation-spin coupling explicitly changes the spin density.
文摘水声通信作为海洋信息传输的核心技术,广泛应用于海洋探测、海事监管及海底工程等领域。然而,水声信道因双重色散特性而极具挑战性,对系统设计构成重大障碍。尽管正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)技术已在水声通信中得到广泛应用,但其性能仍受限于信道状态估计的准确性。正交时频空(Orthogonal Time Frequency Space, OTFS)调制技术通过将数据转换到时延-多普勒域内传输,能够有效地应对水声信道中的多径效应和多普勒频移,提高通信系统的性能和可靠性。综述了OTFS在水声通信中的关键处理技术,涵盖信道估计、信道均衡及多址接入技术三个核心方面,并从天线拓展、机器学习融合及同步创新等方面探讨了未来发展趋势,同时详细分析了复杂信道环境下的信号检测、计算复杂度与实时性平衡、参数估计准确性及水下环境对数据可靠性的影响面临的技术挑战。
文摘随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time linear equalizer,CTLE),该均衡器采用2级级联结构来补偿信道衰减,并提高接收信号的质量。此外,自适应模块通过采用符号-符号最小均方误差(sign-sign least mean square,SS-LMS)算法,使抽头系数加快了收敛速度。仿真结果表明,当传输速率为16 Gbit/s时,均衡器可以补偿-15.53 dB的半波特率通道衰减,均衡器系数在16×10^(4)个单元间隔数据内收敛,并且收敛之后接收误码率低于10^(-12)。
文摘常规的精密单点定位(Precise Point Positioning,PPP)算法中尚未考虑附加先验信息约束的方法,当系统存在固有的先验信息时,不加以利用可能会导致信息的浪费。对此,本文重点研究了车辆直线运动轨迹所存在的约束信息,推导整理了空间直线斜截式约束方程,同时结合等式约束滤波方法中的准确测量法应用到PPP的参数估计过程中,形成附加直线轨迹约束的PPP方法。实验表明:在铁路直线轨道约束实验中,收敛时间最高减少60%,定位精度最高提升14.94%,不同实验结果均表明附加直线轨迹约束能提高PPP定位性能。
