含有关联噪声的非线性分数阶系统的扩展卡尔曼滤波器设计

针对含有过程和测量噪声的连续时间非线性分数阶系统的状态估计问题,提出了扩展卡尔曼滤波器算法.采用Grünwald-Letnikov差分定义对非线性分数阶系统离散化.利用输出方程设定待定系数矩阵,得到离散化的差分方程,实现非线性分数阶系统的有效的状态估计,提高状态估计的精度.最后,给出一个实例来说明所提出非线性分数阶系统的扩展卡尔曼滤波器的有效性.     

基于差分进化的Unscented FastSLAM2.0算法

针对Fast SLAM2.0算法中重采样过程带来的"粒子耗尽"问题,将差分进化引入进来,提出一种基于差分进化的无迹Fast SLAM2.0算法。首先采用unscented粒子滤波器估计机器人的路径后验概率,然后采用扩展卡尔曼滤波器对环境路标进行估计和更新,最后引入改进的差分进化算法代替重采样过程来优化粒子。仿真实验表明,与Fast SLAM2.0算法相比,该方法提高了机器人在路径估计和路标估计上的精度,验证了算法的有效性。     

一种SINS/GPS紧组合导航系统的改进自适应扩展卡尔曼滤波算法

针对自适应扩展卡尔曼滤波算法中系统噪声协方差矩阵与量测噪声协方差矩阵不能同时被估计的问题,提出了一种改进的自适应扩展卡尔曼滤波算法.该算法基于残差,主要对滤波算法中的自适应估计器进行改进,改进后可以实时估计系统噪声.基于该算法,设计了新的滤波器并应用在SINS/GPS紧组合导航系统上,可随着系统中噪声的变化而自动地调节协方差矩阵.最后,分别用扩展卡尔曼滤波和改进的自适应扩展卡尔曼滤波对SINS/GPS紧组合模型进行仿真,结果表明改进的自适应的扩展卡尔曼滤波比扩展卡尔曼滤波的定位误差与测速误差更小,滤波的稳定性更好.      

基于自适应扩展Kalman滤波器的永磁同步电机无速度传感器控制

通过引入一种基于Sage-Husa噪声估计器的自适应扩展Kalman滤波器,给出了一种永磁同步电机无速度传感器控制方案.选取定子固定坐标系下的电机模型,首先得到了基于扩展Kalman滤波器的永磁同步电机转速估计方程.在此基础上,结合Sage-Husa噪声估计器,得到了基于自适应扩展Kalman滤波器的永磁同步电机转速估计方程.仿真结果表明,基于自适应扩展Kalman滤波器的方法,不仅可以准确地估计出电机的转速和转子位置,而且可以自适应确定扩展Kalman滤波器的一个关键参数——系统噪声协方差矩阵.与传统的扩展Kalman滤波器方法相比,本方法具有更好的实用性.     

基于粒子群算法和平方根平淡卡尔曼滤波的北斗导航系统定位估计算法

为提高北斗定位系统(BDS)的估计精度,克服传统平淡卡尔曼滤波(UKF)算法中可能因状态量协方差矩阵失去正定性而导致滤波器发散的问题,将平方根平淡卡尔曼滤波(SRUKF)算法应用于BDS定位估计.在此基础上,为进一步提高SRUKF算法的性能,引入粒子群优化(PSO)算法,提出基于PSO和SRUKF算法的BDS定位估计(PSO-SRUKF)算法.结果表明,PSO-SRUKF算法可以降低系统噪声和测量噪声特性估计不准确带来的误差,有效提高了BDS定位精度和稳定性.     

粒子群优化平方根强跟踪CKF及应用

提出一种粒子群优化平方根强跟踪容积卡尔曼滤波算法,并将其用于水下应答器辅助航位推算组合导航系统. 以强跟踪滤波器为理论框架,结合容积卡尔曼滤波器,设计了平方根强跟踪容积卡尔曼滤波器. 提出一种改进的粒子群算法,将粒子两两为一对分成若干对,每进化一次后,比较两个粒子的代价函数值,代价函数值较优的粒子,搜索方向侧重于群体历史经验,代价函数较差的粒子,搜索方向侧重于自身历史经验. 将改进的粒子群算法用于求取强跟踪滤波器的渐消因子. 仿真结果表明在系统模型不准确的情况下所提算法依然能够有效跟踪状态变化,比传统的容积卡尔曼滤波器具有更高的滤波精度和稳定性.      

基于粒子群算法的自适应滤波器研究及应用

针对神经网络自适应滤波器易于陷入局部极小的缺陷,采用抑制局部最优的粒子群算法优化神经网络的权系数,设计了基于改进粒子群算法训练的三层神经网络的自适应滤波器,并将其应用于自适应噪声抵消器.仿真表明,该系统与传统自适应噪声抵消系统相比具有很好的噪声抵消能力,信噪比大大提高.     

电力系统动态状态估计算法研究

为了提高电力系统动态状态估计的估计精度和收敛速度,引入一种解决非线性滤波问题的新型粒子滤波算法——混合卡尔曼粒子滤波器(Mixed Kalman Particle Filter,MKPF)。该算法采用扩展卡尔曼滤波器(EKF)与无迹卡尔曼滤波器(UKF)混合作为建议分布,得到一种更接近真实分布的近似表达式。仿真算例将MKPF与EKF和UKF进行了对比,比较结果证明在电力系统受到扰动之后,MKPF算法能够快速地收敛于真实值,且具有比EKF与UKF更高的估计精度和稳定性,达到了在线准确估计的要求。     

基于粒子群优化的移动机器人SLAM方法

针对传统Rao-Blackwellized粒子滤波器存在的粒子消耗问题,提出了一种基于粒子群优化的移动机器人同步定位与制图方法. 该方法在粒子重采样过程中利用粒子群优化算法获得机器人位姿的建议分布,并引入遗传算法中的交叉和变异操作对求得的粒子集进一步优化、调整. 改进后的粒子分布保持了粒子的多样性,有效提高了机器人位姿估计的一致性. 仿真结果表明,本文提出的方法与传统Rao-Blackwellized粒子滤波器相比,能有效解决粒子耗尽问题,使机器人获得更精准的定位和更准确的地图,具有可行性、实用性.      

组合导航系统新息自适应卡尔曼滤波算法

全球定位系统(GPS)量测噪声的不稳定变化将造成惯性导航系统(INS)/GPS舰用组合系统卡尔曼滤波器性能下降,在对自适应卡尔曼滤波器分析的基础上,提出了一种新的基于新息估计的自适应卡尔曼滤波算法.该算法通过计算新息方差强度的极大似然估计最优估计,将新息方差计算直接引入卡尔曼滤波器的增益计算.仿真结果表明,本文方法较标准卡尔曼滤波器可以提高系统精度和抗干扰能力.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has