混合动力汽车模糊神经参考控制策略优化

为提高并联式混合动力汽车控制策略精准性,建立了基于发动机效率的模糊逻辑控制器,进一步使用神经网络模型对模糊逻辑控制器的隶属度函数进行在线学习,引入变尺度优化方法的改进型学习算法,完成了隶属度函数的在线学习后的优化;通过模型参考构成闭环在线修正,降低输出转矩的误差。通过循环仿真实验,利用模糊神经参考模型控制策略,发动机工作效率点与实时工况的匹配率更高稳定性更好,发动机平均效率提高4. 16%,峰值电源荷电状态保持在稳定的容量范围内,整车燃油经济性得到改善。因此该控制策略具有较强的工程实用性。     

基于遗传算法的城域交叉路口两级模糊控制

分级模糊控制能有效减少模糊规则数,易于提取模糊规则,适合于交通状况复杂的城域交叉路口的交通控制,但它存在难以由人工合理定义全部模糊隶属度函数的问题.为此,提出了一种面向城域单交叉路口的自适应两级模糊控制系统,并采用遗传算法对两级模糊控制器中模糊隶属度函数进行优化调整.该控制系统具有分级模糊控制的优点,同时可以让模糊隶属度的选取更为合理,使模糊隶属度函数在不同交通情况下自适应地变化,从而改善控制效果.对一个两相位孤立交叉口进行仿真.结果表明该法能有效降低通行车辆在交叉口的平均等待时间.     

模糊自整定PID算法在应力速度控制系统设计中的应用

选用高斯函数作为模糊子集E,ΔE,U隶属度函数,确定了模糊控制规则。设计出的基于模糊自整定PID的控制器在研制的材料测试机集成数据采集及控制系统的应力速度控制系统中进行了应用验证。验证结果表明,应力速度控制得到实现,且集成度高、稳定性好。     

汽油发动机空燃比PID控制及其实验研究

针对汽油发动机气缸进气量变化引起空燃比变化的问题,设计一种基于PID的反馈控制器保证空燃比能够快速恢复到理想值。首先给出一种基于模型的进气量估计算法,在此基础上设计了空燃比前馈控制器;然后将前馈控制与PID反馈控制相结合实现发动机喷油量的调节,利用基于实际实验数据构建的仿真器对提出的算法进行数值仿真研究与分析;最后通过发动机实时控制实验平台验证了控制算法的有效性。     

基于模糊神经网络的参数自整定PID控制系统设计

利用多层神经网络构建模糊自适应PID控制器，通过神经网络自学习能力在线提取模糊控制规则，优化控制器隶属度函数，根据不同时刻的误差e和误差变化ec运用模糊推理在线自整定PID参数。仿真实验表明，该控制系统具有优良的控制性能。此外，通过遗传算法对模糊神经网络的学习速率和惯性系数等进行了优化，为控制系统实现最优控制提供了有力保证。     

汽油发动机空燃比控制系统

对于化油器式发动机 ,为降低其排放污染 ,较为有效的措施是采用空燃比闭环控制加三元催化转换器。本系统采用 PIC单片机和模糊控制算法 ,依据 GB1 4761—1 999规定的 1 5工况法在桑塔纳、捷达、夏利、富康、奥拓几种轿车上对控制系统进行了实车实验 ,结果表明在稳定工况下空燃比被控制在理论值附近 ,尾气排放量在规定的限值以内 ,系统鲁棒性好 ,算法易于实现。     

基于改进模糊PID算法的空燃比控制策略研究

对发动机瞬态工况空燃比进行控制时,由于单缸汽油机本身固有的非线性和时滞环节,传统PID控制很难取得满意的效果,本文构造了一种带动态补偿的模糊PID控制器.首先搭建了单缸机仿真模型,并将模糊PID控制算法应用于空燃比控制中,以适应系统的非线性;然后针对单缸机系统中固有的时滞环节提出一种动态时滞补偿器,以降低时滞环节对系统的影响;再将该时滞补偿器耦合于模糊PID控制器中,应用于单缸机瞬态工况下的空燃比控制.仿真结果表明,改进的模糊PID控制器不仅能补偿系统中时滞环节带来的非最小相位影响,而且能很好地适应发动机系统的非线性特征,从而使控制系统的稳定性、准确性、快速性均得到了很大的改善.     

自适应模糊PID轧机液压AGC系统特性研究

针对液压厚度自动控制系统(Automatic Gauge Control,简称AGC)存在时滞性、时变性的问题,以及传统PID控制器的PI参数无法在线实时修改的局限性,提出了结合模糊控制理论,设计构造模糊自适应PID控制器的解决方法。即确定输入和输出变量,定义各变量的隶属度函数,求解输入变量和输出变量的比例因子,建立系统的模糊规则表,利用重心法解模糊后,实现实时在线调整PI参数的目的。通过MATLAB仿真实验,对系统的时域特性及频域特性进行分析,得到模糊自适应PID控制器比传统PID控制器能够更快速的达到稳定,系统无超调量,无稳态静差,抗干扰能力强,取得了较好的控制效果。     

MATLAB在电液伺服模糊控制系统仿真中的应用

以MATLAB6.1为基础, 简要介绍了模糊控制工具箱的基本函数及simulink工具箱的功能,同时结合电液伺服模糊控制系统实例,详细阐述了利用simulink交互式仿真模块库建立系统框图、利用fuzzy工具箱创建模糊推理关系、设置隶属度函数、建立模糊控制规则,实现对模糊控制器设计的具体步骤及借助MATLAB对控制系统进行仿真研究的方法.     

模糊自适应控制算法在水轮机调速器建模中的应用

在模糊控制器的设计中,模糊规则的提取,比例、量化因子和隶属度函数的确定都具有一定主观性;针对这种情况,提出改进的模糊自适应PID控制算法(IFPID),利用微粒群算法对经过预处理的隶属度函数进行优化.在水轮机调速器仿真实验中,与简单PID控制算法和一般模糊控制算法相比,基于改进模糊自适应PID算法的系统在响应频率扰动和负荷扰动时有着更短的调节时间和更小的超调量.     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has