立体深度运动引发的立体视觉疲劳的脑电评估

3D技术的发展受到其引发的不舒适感的限制,长时间观看立体显示影像将会引起立体视觉疲劳,一种客观评价立体视觉疲劳的有效指标亟待提出.本文利用EEG(electroencephalography)三个频带θ(4~8 Hz)、α(8~13 Hz)、β(13~22 Hz)的相对能量及其能量比值E(α+θ)/β、Eα/β、E(α+θ)/(α+β)在八个不同脑区及整个脑区的54个指标作为备选,借助配对t检验、灰色关联度分析(GRA)、支持向量机(SVM),最后得出指示由立体深度运动引发的视觉疲劳的最佳脑电指标为:顶区Eα/β.并比较了三个频带相对能量在不同疲劳状态的变化:疲劳状态下,α频带明显上升(p<0.01),β频带明显下降(p<0.01),θ频带保持稳定.     

KIVA智能仓储系统中储位分配问题研究

亚马逊公司的KIVA智能仓储系统是目前正在使用且相对成熟的"货到人"拣选系统,在"货到人"拣选模式下如何分配货物的存储位置直接关系到KIVA智能仓储系统的拣选效率.依据ABC库存规则,实际中经常存在所需分配的货格数大于等于货架数的货品.基于该特点,对已有KIVA智能仓储系统中储位分配问题的数学模型进行改进,并提出了改进...     

基于脑电的轻装作业操作者脑力负荷与绩效的分析

针对脑力负荷过高或过低导致产品质量低、生产效率低的问题,采用脑电(EEG)生理测量技术,模拟轻装产品的手工装配生产。设计了单产品装配和产品组合装配实验方案,探究操作者脑力负荷与工作绩效之间的关系。采集了25位志愿者的EEG负荷指标、装配完成率和装配时间三种指标数据,分析结果表明:EEG负荷指标的波动趋势可以有效地反映操作者的任务绩效,但波动状态与具体装配任务有关;与单产品装配方式相比,产品组合装配方式可以在保证装配质量的前提下有效缓解操作者脑力负荷。研究结果提升了手工装配作业下操作者脑力负荷波动状态的认识,有助于管理者制定更优的产品生产计划方案。     

草原公路长时程行车时驾驶人的脑电特征分析

草原公路具有景观单调,行车视距大,平、纵曲线设置不合理,交通流量小等特征,易引起驾驶疲劳,诱发交通事故。选取草原公路进行模拟驾驶,应用MP150多通道生理信号采集仪,采集12名司机4 h模拟驾驶过程中的脑电(EEG)数据,探寻模拟驾驶条件下驾驶过程中EEG相关指标的特征。结果表明:β波及(α+θ)/β这两项指标能较好地反应司机脑电的变化过程;当行驶到20 min时,驾驶疲劳第一次出现;当行驶到60 min时疲劳第二次出现;当行驶到90 min时疲劳第三次出现,当行驶到120 min时疲劳第四次出现;男司机行驶到170 min时和女司机行驶到160 min时驾驶疲劳增加明显,此时,司机应停止驾驶任务,进行调整休息;男、女司机的驾驶疲劳具有累计效应,且驾驶疲劳的累计变化量与驾驶时间具有较强的相关性。     

基于EEG熵值的驾驶员脑力负荷水平识别方法

为了对驾驶员脑力负荷予以有效识别,基于脑电信号指标构建了一种驾驶员脑力负荷识别方法.对驾驶员脑电信号进行快速傅里叶变换(FFT),选取θ(4~8 Hz),α(8~13 Hz),β(13~30 Hz)3个频段的频谱幅值分别进行熵处理,对所得到的熵值作为脑力负荷识别参数,并对识别参数进行Kruskal-Wallis检验,选取差异最为显著的10项参数作为脑力负荷特征指标,在此基础上结合BP模型构建了驾驶员脑力负荷识别模型.基于驾驶模拟器实验数据,模型识别正确率为87.8%~90.4%.结果表明,该模型对驾驶员脑力负荷识别具有较高准确性,可实现不同驾驶员脑力负荷的有效识别,为未来自动辅助驾驶系统构建及车载信息系统优化设计提供算法依据.     

矿工疲劳的ERP特征

煤矿井下设备操作不仅要求矿工保持警戒状态,而且需要持续地将注意力集中在单调枯燥的操作任务和体力作业任务上。由于长时间的轮班和重复性任务,矿工极易出现精神和生理疲劳。为了研究矿工疲劳对其安全能力的影响,应用事件相关电位(ERP)技术,研究Oddball任务下一线矿工下井前后脑电特征变化,从而获取疲劳评价的客观指标。通过测试和采集自愿参加实验的14名夜班矿工下井前后的主观疲劳水平、行为表现指标和脑电信号数据,对诱发ERP特征的波幅和潜伏期进行分析,从而确定矿工疲劳的主要影响因素。从主观疲劳评价和行为表现指标的角度分析可得,夜班矿工下井前后精神状态差异较大;进一步分析矿工ERP特征的变化,发现上井后P300的潜伏期显著增加,波幅明显下降,说明井下一线高负荷连续作业任务导致矿工的精神疲劳增加。ERP方法可用来研究矿工的疲劳程度;P300可以作为评价一线矿工疲劳的有效指标,从而为研究矿工疲劳的对抗措施提供依据。     

基于脑电的水平运动立体影像视疲劳评估

针对长时间观看水平运动立体视频所引发的视觉疲劳这一现象,采用单一运动形式的水平立体视频刺激为实验素材,通过主观实验对比分析被试观看同样的3D素材与2D素材后所引起疲劳感受的差异性.分别采集被试疲劳前后的EEG(electroencephalography)信号与ERP(event related potentials)信号,提取疲劳前后30个电极EEG信号的θ、?、β3个波段小波系数的均值及其比值、、θ/(?+β)、(?+θ)/β、θ/β、(?+θ)/(?+β)作为时频域特征,提取样本熵作为脑电信号的非线性特征.将时频域特征与非线性特征作为联合特征进行立体视觉疲劳评估,避免了单一特征的局限性,多角度分析了视觉疲劳前后特征参数变化.实验结果表明,3D与2D视频均能够使被试在一定程度上产生视觉疲劳现象,且3D显示比传统2D显示对人的影响更大.对比分析ERP信号发现疲劳状态下的N200和P300成分幅值明显下降,而潜伏期略有增加.通过可分性指数FCSI(Fisher’s class separability index)算法、支持向量机SVM(support vector machines)、基于互信息的特征选择算法等筛选出评估水平运动视觉疲劳的最佳特征参数为CP3电极上的?/θ.同时,结合脑区分析发现,与水平运动立体视频关系最为密切的两个脑区可能为顶区与前额区.     

磨矿过程控制中专家操作人员脑电特征分析

面向选矿生产系统的优化和智能升级,为进一步保证产品的质量和产量,针对磨矿过程中操作人员行为因素的评定和量化问题,提出一种基于脑电信号(EEG)特征的实时分析方法.首先采用小波分解的方法提取大脑不同脑区的δ,θ,α和β波节律.然后通过小波各尺度的能量序列、分布计算不同脑区EEG的小波熵,根据小波熵的熵值比较确定待分析的脑区.根据小波时频分析的结果确定谱特征(α+β)/(δ+θ+α+β),最后采用B样条拟合及滑动窗,进行实时评定.结果表明,提出的量化指标可以在一定程度上反映操作输出的粒度曲线的变化趋势,能够较为客观地评定操作人员的行为因素.     

脑疲劳状态下脑功能网络研究与分析

旨在研究连续长时间脑力活动引发的脑疲劳对大脑连接性的影响,探索大脑疲劳评价的客观指标.通过持续认知任务实验诱发脑疲劳,选用互相关方法对采集到的脑电信号进行了不同导联间时域关联特性分析,构建并比较分析了正常态和脑疲劳态的脑功能网络.最后基于复杂网络理论对脑功能网络的特征参数进行了统计分析.结果表明,持续认知任务后,主观感觉疲劳程度显著增加,脑功能网络的平均度、平均聚类系数和网络密度与正常态相比均显著降低,而平均路径长度显著增大.脑功能网络参数可以很好地反映脑疲劳后大脑的连接性变化情况.     

紧固件分拣中心拣选策略的动态EIQ分析

紧固件行业是一个多品种、大批量,需求变动较大且提前期较短的行业,因此分拣系统的规划极其重要。通过EIQ和动态EIQ的方法,可以分析订单的特征,从而为拣选策略的制定提供参考依据。通过对实际数据的分析表明,运用EIQ结合ABC分类的方法可以有效得对拣选中心进行规划,使其适应订单的分拣需求,提高分拣效率和设备的利用率,具备良好的经济性和扩展性。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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