疲劳状态下EEG信号α波的最大李雅普诺夫指数估算

脑电信号(EEG)的α波在人体的疲劳评估中具有重要作用,通过脑电信号的α波,可以挖掘更多的有关人体疲劳的信息.利用非线性动力学的方法对EEG信号α波进行了研究,比较了疲劳与非疲劳EEG信号α波之间的非线性动力学上的差别.人在疲劳与非疲劳下的EEG信号α波最大李雅普诺夫指数是不同的,当出现疲劳时指数减少,因此李雅普诺夫指数可作为人体是否疲劳状态的特征刻画指标.文中非疲劳状态的最大李雅普诺夫指数为0.436 67,疲劳状态者的最大李雅普诺夫指数是0.335 57,它们均为混沌信号,但是处于疲劳状态节律的混沌程度明显比处于非疲劳状态的混沌程度低.     

基于状态空间的EEG信号分析

为寻求脑电(Electroencephalogram,EEG)分析的新途径,提出了一种基于状态空间的脑电分析的新方法.利用状态空间点间的欧氏距离来计算脑电状态空间的态密度和态方差.实验结果表明,态密度和态方差不仅计算简单,而且与脑电的关联维数和Lyapunov指数相比,更能有效地反映混沌系统非线性动力学的特征.此外,还计算了基于距离协方差的脑电信号的奇异谱,并对结果作了分析.     

EEG信号数学模型与广义非线性动力学方程

从脑电信号与非线性动力学各种物理量之间的对应关系人手,在Van der Pol方程基础上推导了表达脑电信号的广义非线性动力学方程组系统,讨论了该系统的特性和3种求解方法,指出混沌系统内部存在吸引子突然消失(边界激变)或膨胀(内部激变)现象.     

不同思维模式下的脑电奇异谱分析

人脑是极为复杂的系统,脑电(EEG)是脑内大量神经元电活动合作与竞争的综合反映,由局部和非局部频率分量构成,这些局部分量与特殊的内在神经网络状态紧密相关,在宏观上反映了脑的机能状态.脑电信号的非线性分析是近年出现的一种脑电分析方法,它反映了大脑处理信息活动的有序程度,为研究大脑高级认知活动提供了新的思路.越来越多的研究表明,传统的非线性动力学方法采用单一的参数不能充份描述脑电信号的复杂行为,多重分形用一个谱函数从不同层次描述了分形体的整体生长特征,采用多重分形方法描述系统的非线性动力学行为能够得到更多的信息.本文对不同思维模式下脑电的多重分形特性进行分析,发现EEG的奇异谱在不同的思维状态下具有差异.进一步对这种差异进行统计分析表明大脑思维的EEG多重分形特性受到人脑的思维方式的影响,EEG多重分形奇异谱强度分布反映了大脑思维模式的差异.     

EEG的测度熵计算

本文对脑电图(EEG)的测度熵进行数值计算,证实了脑电呈现混沌运动的特征,并发现可以利用EEG的测度熵对人脑功能作定性解释。     

基于盲反卷积的脑电信号盲分离研究

采用卷积混合模型描述观测脑电信号(electroencephalogram,EEG),提出一种基于盲反卷积的EEG盲分离方法.结合EEG源成分的独立性确定代价函数,并采用共轭梯度法进行迭代寻优.针对EEG仿真实验数据进行方法验证,采用分离信号与源信号之间的相关系数作为验证指标.实验结果表明,本文方法可以较好地实现EEG盲分离,为EEG信号处理和其他生理信号处理分析提供理论和方法借鉴.     

基于时空特征学习Transformer的运动想象脑电解码方法

脑电图（Electroencephalography,EEG）可记录来自大脑皮层的电信息，反映了脑活动中神经细胞放电产生的电场变化情况. EEG的空间信息和时间信息对于运动想象脑电（Motor Imagery Electroencephalogram,MI-EEG）解码分类模型学习判别特征至关重要，但过度依赖预处理和手工特征提取，导致对EEG数据进行信号分类较为困难.尽管深度学习已经在很多领域实现了自动特征提取，但脑电图的深度学习尚未完成.提出基于FBCSP (Filter Bank Common Spatial Patterns)和Transformer模型的时空特征学习的运动想象脑电解码方法 .针对FBCSP滤波的脑电信号，依次通过空间维度和时间维度上的注意力转换来获取空间和时间特征，然后通过Softmax函数对不同类别的EEG数据进行分类.实验结果表明，在BCI竞赛数据集IV-2a上，该方法的分类准确率可达84.16%，为MI脑电信号分类提供了新思路.     

脑电信号的现代分析方法

脑电图（EEG）是脑神经细胞电生理活动在大脑皮层或头皮表面的总体反映。临床实践表明，脑电信号中包含了大量生理与疾病信息，通过对脑电信号的处理，不仅可以为医生提供临床诊断依据，而且可以为某结脑疾病提供有效的治疗手段。作者从脑电信号的分析出发，论述了频域分析、时域分析等脑电图分析中常用的信号分析方法和特点，特别介绍了Wigner分布、小波变换和匹配跟踪等时频分析方法、人工神经网络和非线性动力学方法在脑电信号分析和处理中的应用情况。     

基于原型网络的小样本脑电伪迹检测方法

正常脑电信号由于容易受到多种脑电伪迹的干扰而导致信噪比低，为了提高脑电信号的信噪比，使用一种基于度量的小样本学习模型来检测脑电信号中的伪迹，提出了一种基于原型网络的脑电伪迹识别模型(EEG Artifact Prototype Network，EAPNet)。该模型能够学习一个从EEG特征到目标空间的非线性映射，然后计算每个类原型表示的距离，并按此距离进行分类; 仅需较少数量的数据样本进行训练，就能实现对伪迹的准确识别。最后，在公开的脑电伪迹数据集TUAR(TUH EEG Artifact Corpus)中进行了伪迹识别实验，并将EAPNet模型与2个深度学习模型(EEGNet、全连接神经网络(FNN))及7个机器学习模型(高斯贝叶斯模型(Gaussian NB)、随机森林模型(RF)、逻辑回归模型(LR)、套索回归模型(Lasso)、支持向量机模型(SVM)、岭回归模型(Ridge)和最近邻算法(KNN))进行了对比实验。实验结果显示:(1)EAPNet模型是一种高效的伪迹检测方法:在2-way 1-shot、2-way 5-shot、2-way 10-shot任务中，模型的检测准确率分别为69.44%、77.21%、80.01%。(2)在所有对比模型中，EAPNet模型的识别准确率最高。     

中心球模型下EEG正问题的数值模拟

目前EEG已经成为脑功能研究和临床诊断的重要技术手段.在研究EEG反问题时,大量的EEG正问题的计算是必不可少的.一方面,基于加权残值边界元法建立EEG正问题的计算公式,针对中心球模型,对不同偶极子的位置和方向分别计算了脑皮电位势.另一方面,针对EEG正问题的数值模拟,比较脑皮电位势的数值解与解析解的差异.结果表明加权残值法较以往的有限元法、差分法计算效率和精度都明显提高.因此广泛应用在计算力学的研究中.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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