驾驶员前向避撞行为特征的降维及多元方差分析

驾驶员在追尾临撞工况下的避撞过程可以分为多个阶段(如制动前、制动后),而在每一阶段中,又存在多个分析角度(如制动快慢、制动力度)及不同的关键时刻与特征值,因此系统描述驾驶员的避撞行为需要多种参数.对多种避撞行为参数进行降维处理,并探究工况紧急程度对每类参数的综合影响.利用同济大学8自由度高仿真驾驶模拟器,研究驾驶员在不同前车减速度(0.30g,0.50g,0.75g)和不同初始车头时距(1.5s,2.5s)下的避撞行为,全面记录了驾驶员危险感知、油门释放和刹车制动等避撞行为参数.利用主成分分析对众多参数进行降维处理,将避撞行为特征划分为感知反应、制动延误、制动力度3个方面,并通过多元方差分析探究车头时距、前车减速度及二者交互项对这3个方面的影响.结果表明,驾驶员感知反应受到车头时距和前车减速度同时影响,制动延误受到车头时距、前车减速度以及二者交互项的影响,制动力度则仅受到前车减速度的影响.在变化趋势上,随着工况紧急程度的增加,驾驶员的感知反应越快,制动延误越短,而制动力度越大.     

智能汽车自动紧急控制策略

结合驾驶员在紧急工况下的驾驶行为以及不同避撞方式的避撞效能,对以自动紧急制动系统(Autonomous Emergency Braking,AEB)为代表的控制策略进行分析,发现当前的紧急制动控制策略并不能很好地适应驾驶员行为和满足避撞效能的需要.为此,提出了一种融合制动控制和转向控制的自动紧急控制(Autonomous Emergency Control,AEC)策略.在该策略中驾驶员始终在环,系统通过集成驾驶员模型、车辆模型和道路环境模型信息判断驾驶员的行为是否正确,并将控制输入与驾驶员输入叠加在一起作为车辆的输入对驾驶员不当驾驶行为进行纠正.     

工况紧急程度对驾驶员避撞行为的影响

利用同济大学8自由度高仿真驾驶模拟器研究了临撞工况紧急程度对驾驶员避撞行为的影响.通过不同初始车头时距(1.0 s,[1.0 s,1.5 s),[1.5 s,2.5 s])和不同前车减速度(0.30g,0.50g,0.75g)的组合,建立了不同紧急程度的前车减速临撞工况,运用驾驶员感知反应时间、油门释放反应时间、制动转移时间、制动延误、最大刹车踏板压力、最大减速度等指标比较了不同紧急程度下避撞行为的差异.结果表明,①随着工况紧急程度的增加,驾驶员更快地释放油门及达到最大刹车踏板压力,并且施加更大的制动力度;②当初始车头时距为1.5 s左右时,驾驶员感知反应时间约为1.2s,而当初始车头时距增大到2.5 s以上时,感知反应时间变得非常大,甚至达到了3 s;③驾驶员开始释放油门与开始制动间的转移时间不受工况紧急程度影响,保持在0.8 s附近;④在低紧急程度下,驾驶员表现出多阶段刹车行为,使得驾驶员需要更多的时间才能达到最大刹车踏板压力.     

紧急避撞路径规划及其跟踪驾驶员转向模型

针对紧急避撞工况,提出并设计了一种紧急避撞路径规划方法和路径跟踪反馈预瞄驾驶员模型。首先,提出了一种基于Sigmoid曲线与物理约束的避撞路径规划方法,并建立融合最优曲率预瞄与闭环反馈转向修正的驾驶员模型以对所规划路径实现快速和精确跟踪。之后,搭建了CarSim+Simulink离线联合仿真平台,对避撞路径规划和路径跟踪反馈预瞄驾驶员模型的有效性进行了验证。最后,基于自主改装的试验车辆,进行实车试验以验证所提出的路径规划方法及驾驶员模型的可行性与实时性。仿真及实车试验结果均表明,所规划的避撞路径和驾驶员模型可以控制车辆快速、安全地避让障碍物。     

基于自然驾驶数据的驾驶员紧急转向变道模型

提出了一种以驾驶员转向目标瞄点为核心的、面向操纵层的驾驶员紧急转向变道的模型建立方法.基于驾驶员紧急变道的阶段特征,提出了驾驶员紧急变道侧向运动轨迹的规划方法,并结合远近目标点理论分析方法,分阶段建立了驾驶员转向变道工况的驾驶员转向模型.对紧急转向变道中避撞、侧移和稳定阶段的增益因子的分布特征进行了研究,模型能够真实地预测自然驾驶中的紧急转向变道行为.     

基于驾驶倾向性辨识的避撞-报警算法

为了研究适应驾驶员个性需求的避撞-报警算法,将驾驶倾向性作为驾驶员的个性评价指标引入。以实车实验所得驾驶行为数据为基础,提出了一种驾驶倾向性的实时辨识方法。通过驾驶模拟实验,获取了不同驾驶倾向性驾驶员的反应时间和制动减速度数据;并据此提出了一种基于驾驶行为的避撞-报警算法;最后将该算法与典型安全距离算法进行仿真对比。结果表明:本文提出的避撞-报警算法具有较高的可信度,而且体现了各类型驾驶员报警触发时机差异。     

基于自然驾驶数据的驾驶员紧急制动行为特征

基于中国自然驾驶数据,建立了紧急工况下制动避撞的驾驶员模型,分析了驾驶员的紧急制动反应时间和紧急制动输入特性的规律特征.结果表明:驾驶员的紧急制动反应时间与驾驶工况的紧急程度相关,以碰撞时刻倒数的临界值0.2s~(-1)作为危险触发阈值,驾驶员的紧急制动反应时间分布为均值0.5s的正态分布;最大制动减速度随驾驶工况紧急程度变化不明显,最大制动减速度梯度随驾驶工况紧急程度的增加而增加.     

自然驾驶工况的驾驶员紧急转向变道行为

基于中国自然驾驶工况数据,提出了紧急工况下驾驶员转向变道行为的特征规律.分析了紧急转向变道避撞、侧移和稳定阶段的驾驶员转向特征,研究了转向持续时间、方向盘转速和转角的线性关系,定义了用高斯函数拟合的转向基元来表征各阶段的转向行为.研究结果表明,转向基元表征了驾驶员转向行为的一般特征,单个转向基元的方向盘最高转速和转角变化线性相关,持续时间恒定,符合人体行为学中趋向行为(reaching behavior)的特征规律.驾驶员的紧急转向变道行为是由多个转向基元组合而成,每个转向基元都是一个开环模型,可通过方向盘最高转速预判驾驶员的转向行为.     

基于纵向避撞时间的预警/制动算法

针对汽车纵向避撞系统的要求,提出了一种基于纵向避撞时间的纵向碰撞预警/避撞(FCW/FCA)算法。通过分析纵向避撞时间与驾驶员反应时间之间的关系,建立了前车不同行驶工况条件下的安全车距模型,并在3种不同行驶工况下,与Berkeley模型进行制动/预警距离的对比。研究结果表明:该算法确定的制动距离与Berkeley模型确定的距离相差很小,并且考虑了前车的运行工况;该算法还能够根据前车行驶工况的不同,确定出合理的预警距离。对比分析结果验证了该算法的有效性和可行性,能够提高车辆行驶的安全性。     

基于纵向避撞时间的预警／制动算法

针对汽车纵向避撞系统的要求,提出了一种基于纵向避撞时间的纵向碰撞预警／避撞（FCW／FCA）算法。通过分析纵向避撞时间与驾驶员反应时间之间的关系,建立了前车不同行驶工况条件下的安全车距模型,并在3种不同行驶工况下,与 Berkeley 模型进行制动／预警距离的对比。研究结果表明：该算法确定的制动距离与 Berkeley 模型确定的距离相差很小,并且考虑了前车的运行工况;该算法还能够根据前车行驶工况的不同,确定出合理的预警距离。对比分析结果验证了该算法的有效性和可行性,能够提高车辆行驶的安全性。     

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.     

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

正~~