基于最小二乘支持向量机的交通流量预测模型

城市交通流具有复杂性、时变性和随机性,实时准确的交通流量预测是实现智能交通诱导及控制的前提.综合分析交通流量影响因素的基础上,进行多路段的交通流量预测研究,提出了基于最小二乘支持向量机的交通流量预测改进模型,并应用平安大街的流量数据进行实例验证.结果表明,该模型具有学习速度快、跟踪性能好及泛化能力强等优点,在交通流预测中更具有实用性和推广性.     

基于网络层析成像技术的道路交通流预测算法

为了更有效地预测城市路网交通流量,本文提出了一种城市道路交通预测模型.该模型基于网络层析成像(Network Tomography, NT)技术建立生成树,采用期望最大 (Expectation Maximization, EM) 算法得到路网子网车流概率分布,再结合路网子网中流量守恒原则,对待预测路段流量进行推测.实验结果表明,该模型优于现常用的人工智能模型,对城市交通流量预测更为有效,且提高了预测精度.     

城市交叉口三左转车道流量均衡性及影响因素

根据多车道流量分布与驾驶员车道选择行为之间的关系,提出多车道设施流量均衡性的建模与分析方法.以城市道路信号控制交叉口三左转车道为例,使用成分数据结构组织各左转车道流量,选取可能对车道流量分布具有潜在影响的7个因素.在单形中建立以三左转车道流量成分数据为因变量、所选影响因素为自变量且满足车道流量占比约束的成分方差分析模型,设计单形操作法进行模型估计.研究结果表明,模型可识别对左转车流分布具有显著性影响的因素,并定量估计各因素对每条左转车道流量占比的影响程度.信号周期长度、交叉口内转弯曲线长度、展宽车道的设置、上游路段长度、上游左转车道标志标线位置和其他流向车道数等因素可在特定设置条件下使车流分布接近均衡.     

基于高斯核函数的短时交通流量预测

交通出行在人们的生活中占据了重要的地位,准确、短时交通流量预测有助于实现交通控制.本文采用基于高斯核函数的Nadaraya-Watson估计方法对短时交通流量进行了预测.以所选取路段的车流高峰时段为研究对象,根据当前时刻的车流量对下一时刻的流量值进行预测,其中相邻两时刻的时间间隔为5分钟;就所选的高斯核函数而言,根据试凑法,选定核函数带宽为8.结果表明,该方法的预测效果良好,其均等系数为0.996545243,达到了很好的预测效果.     

交通事故影响下事发路段交通流量变化分析

以交通事故这种异常事件为例,分别对高速公路基本路段内交通事故影响时间、车辆排队长度、事故影响下不同时间段内不同路段断面流量变化进行了分析。采用交通波理论给出了该事故路段内不同时间段内不同阻塞行车道宽度的车辆排队长度,并对流量变化分析进行了仿真验证。     

基于随机生存森林的交通事件持续时间预测

采用随机生存森林模型开展交通事件持续时间分析,克服了传统决策树模型易过度拟合和传统生存分析需限制性假定及识别协变量交互作用的缺陷.该研究基于上海城市快速路网交通事件数据,结合道路几何线形、交通运行、天气状况等数据.原始数据库分为训练数据(80%)和测试数据(20%).分析结果表明事件类型、路段长度、发生地点、剩余车道数、交通流量等变量对交通事件持续时间有显著影响;影响时间预测准确率结果表明随机生存森林模型预测精度显著优于随机森林的预测精度.     

基于WiFi探针数据的短时交通状态预测

针对传统交通数据获取成本高,以及单参数输入的LSTM模型预测精度不高等问题,提出一种基于WiFi探针数据的短时交通状态预测方法.首先利用WiFi探针数据构建交通状态指数数据集,然后采用LSTM网络构建预测模型,并分析不同交通参数组合对模型预测精度的影响,最后比较不同模型对同一路段的预测性能.试验结果表明:交通流量会影响...     

路段多车型混合车流通行能力

利用概率论方法,通过对由多种车型构成的混合车流不同跟驰序列,不同组合概率的研究,得到了跟驰车头时距路段多车型混合车流通行能力模型.基于经典车头间距模型,通过对混合车流不同跟驰序列下最小车头间距的研究,得到了多车型混合车流的组合车头间距,进而得到了跟驰车头间距路段多车型混合车流通行能力模型.推广了由大、小2种车型构成的混合车流的通行能力模型.研究表明,路段多车型混合车流通行能力不仅与反应时间、车辆速度、车辆长度、制动性能等有关,还与混合车流的车辆组成状况及跟驰序列相关.最后实例分析了不同小型车混入率情况下路段通行能力的变化状况.     

干线关键断面的到车率分布预测

干线协调控制需要了解交通量在干线上下游的传递和变化关系,传统的行程时间预测或到达分布预测无法提供足够的参考信息.根据干线的道路条件,界定干线上若干个关键断面;统计实际的车辆检测数据或仿真实验数据,按较小的时间间隔汇总和统计不同周期在对应间隔内的到达分布,绘制得到关键断面的到车率分布图.分析路段离散和信号控制对到车率分布的影响;以车速的累积概率分布图为基础计算转移矩阵,提出了考虑路段离散的到车率分布预测方法;分析红灯排队、绿灯放行的车流离散过程,提出了考虑信号控制的到车率预测方法.仿真案例分析表明,预测的到车率分布相对误差较小,验证了预测方法的有效性.     

基于深度学习的高精度交通流量大数据预测

为了高效预测分析海量交通大数据,提高道路通行率和城市交通的智能化水平,提出一种高精度基于深度学习的并行卷积神经网络交通流量大数据预测模型.该模型首先对数据进行预处理以获得有效数据集,将具有规则时间间隔的一维时间序列样本和图像转换为时间一维、位置一维的二维像素网格,构建并行卷积神经网络模型用于对通过某路段的交通流量进行预测,并应用预测因子对交通量流数据进行建模.实验结果表明,与其他模型相比,本文提出的模型在平均绝对误差、平均相对误差和均方根误差方面均优于所对比的方法.     

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     

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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