混合动力挖掘机的建模与控制策略研究

以实现节能为目的,提出了一种应用于并联式混合动力液压挖掘机动力系统的控制策略。分析了该系统各个部分的结构,用AMEsim软件建立了其仿真模型,在MATLAB/Simulink中建立其动力系统控制策略模型,并进行联合仿真。该控制策略以发动机燃油经济性为优化变量,在工作中通过比较SOC值以及负载功率与发动机功率限值来确定发动机工作功率。仿真结果表明,该控制策略在轻载及重载两种工况下均能使发动机保持较好的燃油经济性,有利于系统的高效稳定工作。     

采用功率内环和电压平方外环的电压型PWM整流器

根据电压型PWM整流器在同步旋转dq坐标系中建立的整流器功率控制数学模型,基于功率前馈解耦,解决了有功功率和无功功率互为耦合问题.为克服整流器电流控制策略、直接功率控制策略及非线性控制策略的不足,提出了采用功率内环、直流电压平方外环电压型PWM整流器的新控制策略.由于采用直流电压平方外环,提高了整流器直流电压跟踪和功率跟踪能力,使系统具有响应快、稳定性好、抗负载扰动能力强及结构简单的优点.给出了系统控制器的设计方法.通过正常负载及负载扰动情况下的计算机仿真,证明了新控制策略的可行性.     

三相PWM整流器幅相控制策略

介绍一种三相PWM整流器的幅相控制方法,通过实时检测功率因数角和直流母线电压,来控制整流器输入端电压相对于三相电源电压的滞后角及调制深度,并将该算法进行线性化处理,实现解耦控制和单位功率因数运行.分析了系统稳定工作时参数的变化范围、约束条件及负载扰动时系统的调节过程, 并对三相PWM整流器进行了谐波分析.本控制策略算法简单易行,并得到了实验验证.     

三相PWM整流/逆变系统的李亚普诺夫控制

针对集成的三相PWM整流/逆变系统,提出了一种基于李亚普诺夫直接法的一体化瞬时功率控制策略.主要思想是:选择合适的整流器状态变量构造一个李亚普诺夫函数,从李亚普诺夫渐近稳定性出发,设计两个控制变量用于整流器的控制.该策略将逆变器的瞬时功率动态自然地嵌入到整流器的控制当中,在保证整流器渐近稳定的同时,使得三相PWM整流/逆变系统的直流储能电容可以大大减小.在Matlab/Simulink环境下对采用这种控制策略的系统进行了仿真,仿真结果验证了该策略的有效性.     

基于ECMS混联式混合动力客车工况识别控制策略

由于城市特殊的运行工况,单纯的基于规则控制策略很难从城市复杂的工况中获取最佳燃油经济性.以提高一款新型混联式混合动力客车燃油经济性为目的,为了更好地适应城市复杂的行驶工况,制定了一种工况自适应实时优化控制策略.根据等效燃油最小控制策略思想结合新型混联式混合动力客车的结构特点构建发动机与电池间的功率分配实时优化算法,针对城市循环工况的特点选定了4种典型的工况类型,并获得不同行驶工况和等效燃油转换系数及油耗的关系,经分析发现每一行驶工况都存在相应的等效燃油系数使得其油耗最低,因此采用LVQ神经网络模型对各工况特征参数进行学习训练以进行实时工况识别,利用工况识别的方法获取当前运行的工况类型并选择相对应的等效系数进行周期性更新以期达到最佳燃油经济性,从而实现对不同工况的适应性.仿真结果表明:其燃油经济性比单纯的能量管理优化控制策略提高了8.55%,同时电池SOC能够控制在预定的范围内运行.     

基于哈密顿理论的电压型PWM整流器无源控制

为了提高电压型PWM整流器的性能,提出了基于哈密顿理论的无源控制策略.根据电压型PWM整流器主电路拓扑结构,建立了端口受控的耗散哈密顿(PCHD)系统模型.基于PCHD模型,采用能量成型的方法,设计了PWM整流器无源控制器.该控制器能够使整流器能量函数最小值稳定在期望的平衡点,从而提高了整流器的稳态性能和抗负载扰动能力.仿真结果表明该控制策略的可行性.     

燃料电池混合动力轿车控制策略与参数优化

以某国产经济型轿车为平台,对其动力总成进行了燃料电池混合动力驱动系统的虚拟改装．为提高其整车的经济性和动力性,使用ADVISOR软件对整车性能进行仿真分析,研究了燃料电池混合动力驱动系统开关控制模式和功率跟随控制模式的特性,确定功率跟随控制模式为适合该车型的控制策略．分析了4种典型驱动工况下不同混合动力度的整车经济性及动力性,其中50％的混合动力度是适用于该车型燃料电池混合动力驱动系统最优配置．在此最优配置下,以最小氢气燃料消耗为目标,优化主减速比、燃料电池的最大和最小工作功率以及蓄电池的充电功率,得到了燃料电池混合动力系统的最佳工作点．     

基于FA的等效燃油消耗最小控制策略优化

为了提高混合动力汽车的燃油经济性,研究了基于萤火虫算法(firefly algorithm, FA)优化的等效燃油消耗最小控制策略(equivalent fuel consumption minimization strategy, EFCMS).以并联式混合动力汽车为研究对象,运用萤火虫算法对等效燃油消耗最小控制策略的等效因子以及电池荷电状态(state of charge,SOC)进行优化,实现了并联式混合动力汽车的能量优化控制.在Matlab/Simulink中搭建整车模型进行仿真,结果表明:UDDS(urban dynamometer driving schedule)、NEDC(new European driving cycle)、HWFET(highway fuel economy test)这3种工况下,与优化前相比,节油率分别达到了28.5%、25.5%、16.9%;基于FA的等效燃油消耗最小控制策略相比于传统的等效燃油消耗最小控制策略,可以有效提高燃油经济性,电池SOC可以更好地维持在目标值附近.     

HEV再生制动过程中CVT速比控制策略

考虑混合动力汽车制动安全性和燃油经济性,提出了一种基于电池SOC值和制动强度的再生制动力控制策略.提出了通过调节CVT的速比及控制电机工作在高效区来提高电机发电效率的再生制动控制方法.进行了整车再生制动系统建模和典型城市驱动循环工况下的仿真,结果表明,提出的CVT速比控制策略能使以CVT为变速器的混合动力汽车比以MT为变速器的混合动力汽车在ECE EUDC驱动循环工况下的再生制动能量回收率提高2.86%.     

基于交通信号灯信息的混合动力汽车节能预测控制方法

针对传统混合动力汽车控制方法不考虑已知道路交通信号灯信息对车辆能量管理影响的问题,提出了基于交通信号灯信息的混合动力汽车节能预测控制智能优化策略。通过建立混合动力汽车系统的简化模型,并采用连续广义最小残量方法求解模型预测控制问题。运用MATLAB/Simulink进行仿真,仿真结果验证了交通信号灯信息模型的有效性,以及所设计的模型预测控制算法大幅度提高混合动力汽车的燃油经济性的能力和实时控制性能。研究结果表明所提出的控制策略可以实现车辆行驶轨迹的优化控制,显著提高了车辆的燃油经济性,并满足系统的实时最优控制要求。     

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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