电动助力转向系统稳定性分析

在建立电动助力转向系统数学模型的基础上，对电动助力转向系统的稳定性进行了分析，应用控制理论推导了电动助力转向系统的稳定性判断条件，分析讨论了影响系统稳定性的结构参数等因素，指出了各影响因素的相应解决办法，为电动助力转向系统及控制器的设计与改进提供了有价值的理论依据．研究表明，对于一个设计定型的电动助力转向系统，各机构部件的许多参数很难改变，可以采用改变电子控制单元中助力增益的方法来使系统稳定工作，即在控制器设计中采用较小的助力增益，并通过试验进行了验证．     

蓄能式商用车电动液压助力转向系统

电动液压助力转向系统是一种电控助力转向系统。该文提出了一种带有高压蓄能器及线性电磁阀的电动液压助力转向系统结构,利用高压蓄能器进行储能,利用线性电磁阀进行流量控制,可显著降低转向系统对于驱动电机的功率要求,有效提高系统的可靠性,降低系统能耗。基于Matlab/Simulink建立了电动液压助力转向系统机械子系统、液压子系统、转向阻力系统及控制器的数学模型,进行了仿真研究。完成了原理样机的研制工作,并进行了原地转向试验。试验结果表明:带有蓄能结构的系统可以满足商用车转向需求,具有良好的节能效果。     

基于动态分析的电动助力转向系统设计与研究

介绍了电动助力转向系统的组成及原理,通过对电动阻力转向系统动力学和车辆横向动力学的分析,得到了装有电动助力转向系统车辆的横摆角速度增益函数。在分析影响系统响应速度的因素的基础上,提出了对电动助力转向系统改进设计的办法。     

基于模糊控制的电动助力转向系统控制策略研究

随着现代汽车电子控制技术的飞速发展,电动助力转向(Electric Power Steering,简称EPS)系统正逐步取代传统液压助力转向系统。该文通过对汽车电动助力转向系统的动力学分析,建立了车辆了EPS系统的动力学模型,提出了基于模糊控制的EPS系统助力控制策略,并对其建模仿真,为电动助力转向系统的设计与开发提供理论基础和设计方法。     

汽车电动助力转向系统实验台架的设计

在传统的液压助力转向实验台架的基础上,设计了适用于电动助力转向系统的实验检测台架,包括增加方向盘转角和转矩传感器、转向助力电机和减速机构以及动态数据采集系统,可实现对电动助力转向系统参数的动态检测和分析,综合评价助力特性,为电动助力转向系统的设计及开发提供良好的技术支持.     

汽车电动助力转向系统的仿真研究

该文描述了电动助力转向系统的主要构造及其工作原理,在对其系统进行分析的基础上,采用PD控制器建立了系统的数学模型,并在Matla6.1下的Simulink4.0进行仿真计算,计算结果表明这一模型是正确有效的,这一成果为今后的对电动助力转向系统的仿真开发和研究打下基础.     

电动液压助力转向系统仿真

依据电动液压助力转向(EHPS)系统的参数,运用AMESim软件建立了电动液压助力转向系统仿真模型.分析了车速参与系统控制时对助力特性的影响.相同扭矩下,高速时提供助力较小,低速时提供助力较大.既可保证转向轻便性,又防止高速时转向盘发飘.转向盘角速度参与控制后,提高了系统的跟随性.改善了系统的回正性能.将仿真所得调试控制参数用于实际控制系统中,进行了台架实验.实验结果表明,电动液压助力转向系统的实际控制效果与仿真结果相同.     

电动助力转向系统助力控制策略仿真研究

分析了汽车电动助力转向系统的结构,选择直线型的助力特性曲线进行控制,通过PID控制方法对电机进行控制,建立电机控制的数学模型,并在Matlab/Simulink仿真环境中搭建出电动助力转向系统模型,通过不断地调整控制器参数观察输出结果,直到使系统的控制效果达到最优.     

汽车电动助力转向系统操纵性能评价研究

阐述了汽车电动助力转向系统的特点及类型,对汽车电动助力转向系统操纵性能的评价指标和评价方法进行了探讨。     

电动助力转向系统控制技术的研究

从汽车对转向系统性能要求出发,制定电动助力转向系统的相关控制策略,包括助力控制、回正控制及阻尼控制,并通过相关的软、硬件设计实现该控制策略,可对汽车转向过程的各个环节进行控制．为检验所制定控制策略及所设计控制软件的合理性,进行了电动助力转向系统和进口系统装车对比试验,结果表明,自主研发的电动助力转向系统与进口系统性能接近,不仅转向操纵平顺,而且具有良好的助力特性,基本达到装车使用的要求．     

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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