键合图理论在PEMFC建模的应用

基于汽车控制系统的实时性要求,控制模型必须在保证准确性的同时具有运算简单的特点.质子交换膜燃料电池（PEMFC）被誉为最有前途的车用燃料电池,对其模型的研究是不可或缺的.本文根据车用实时控制的要求结合PEMFC工作原理,利用键合图方法和20-sim软件,建立PEMFC的稳态模型.通过比较仿真结果与实验结果,验证了模型的...     

PEMFC流场的数学模拟

质子交换膜燃料电池（PEMFC）流场是影响其电池性能的重要因素．建立了针对PEMFC流场分析的数学模型，并对5种常见形式的流场进行了模拟计算，考察了其中气体流速及电流密度等物理量的分布情况．模拟结果显示，流场形式对电流密度分布影响很大，适当拉近上游和下游流场之间的距离可以促进电流密度的均匀分布．所建方法可以用来评价流场，对流场形式的设计有指导作用。     

PEMFC内薄膜温度传感器动态特性的数值模拟

通过数值模拟和系统辨识建模,研究了质子交换膜燃料电池（PEMFC）薄膜温度传感器的动态特性,并根据传感器在PEMFC中的位置,建立了传感器的一维瞬态传热模型。采用COMSOL软件的仿真和系统辨识方法,得到了系统动态数学模型、动态性能指标和动态误差。对于绝缘层厚度为1、2、3、5、10 μm的薄膜温度传感器,确定了其工作频带、延迟时间、上升时间及动态误差峰值等指标参数,并且通过实验手段制作和校准了一个薄膜温度传感器。结果表明,随着绝缘层厚度的增加,传感器的动态性能降低。提出通过模型仿真来判断PEMFC内温度传感器能否满足动态测温要求,这将有助于PEMFC内部瞬态温度的实验研究,也可为传感器的参数选择和结构设计提供参考。     

质子交换膜燃料电池电堆温度特性的模糊建模

根据PEMPC电堆温度控制的需要,建立了PEMFC电堆的工作温度与运行参量之间的定量关系模型,为建立面向控制的PEMFC温度非线性模型提供了一种新思路.在建模过程中,采用模糊辨识方法建立PEMFC控制系统的模糊模型,仿真和实验结果表明,该模糊辨识方法对质子交换膜燃料电池电堆的建模和控制提供了一条可供参考的途径.     

电动汽车燃料电池的关键技术和发展趋势

电动汽车燃料电池技术已经成为各国争相研究的热点.质子膜燃料电池(PEMFC)作为新一代发电技术,其广阔的应用前景可与计算机技术相媲美.本文介绍了燃料电池(FC)的工作原理及分类;重点分析了PEMFC的关键技术及其研究现状,并对PEMFC的前景进行预测,并提出相应的发展措施.     

基于Matlab/Simulink和AMESim的PEMFC冷却系统联合仿真

为研究质子交换膜燃料电池发动机冷却系统控制策略,针对45kW PEMFC发动机设计了综合型冷却系统,运用Matlab/Simulink和AMESim软件建立了冷却系统联合仿真模型,模型主要由冷却循环泵、冷却水管路、膨胀水箱、旁路分流阀、散热器和中冷器组成.利用该模型对PEMFC在各工况点的冷却特性进行了仿真,分析了冷却系统各部件对冷却效果的影响,为制定PEMFC发动机温度控制策略提供了依据.     

PEMFC阴极催化层电化学性能的数学模拟

质子交换膜燃料电池(PEMFC)的膜电极中包含多种传输过程,且传输过程与电化学反应过程在相互交错的区域内进行,本文建立了质子交换膜燃料电池的阴极数学模型,运用MATLAB和C语言编写了模拟程序,探讨了电极结构和电极制备工艺对电极电化学性能的影响.     

质子交换膜燃料电池冷启动动态数值模型

利用数值仿真的方法,建立了一种质子交换膜燃料电池(PEMFC)的分层集总多相数值模型,全面考虑了燃料电池冷启动过程中的水热传递和水的相变过程。作为一维多相模型的简化,能够在显著提高计算效率的同时也能保证仿真结果和实验结果较好地拟合。利用该模型,研究了PEMFC电堆在冷启动过程中的温度不一致性和高次型电流加载的冷启动策略,降低了燃料电池成功冷启动的最低温度。此外,提出了一种全新的仿真燃料电池零下环境中极化曲线的方法,能有效评估燃料电池零下环境中的输出特性。     

质子交换膜燃料电池建模研究评述

车用动态工况下,质子交换膜燃料电池(PEMFC)内部压力、温度和气体浓度直接影响整个系统的性能和耐久性,因此需要借助数学模型分析电池内部传质、传热和化学反应过程,以优化燃料电池系统设计及控制。然而,燃料电池是一个非线性、多输入、强耦合的系统,模型的建立涉及从原子分子级尺度,到材料晶格结构级尺度,再到部件、电堆和系统级尺度。针对多尺度建模问题,从关键部件、单体、电堆及系统等角度,对不同尺度的建模方法进行全面梳理,并阐述了未来建模的挑战及发展趋势。     

基于模糊PID的质子交换膜燃料电池输出电压控制

为了保持质子交换膜燃料电池(PEMFC)的输出电压稳定,该文提出了一种电压动态控制模型.设计了一种自适应模糊比例积分微分(PID)控制器.通过3个模糊控制器实时地整定PID控制器参数.当电池负载发生变化时,通过调节氢气流速控制PEMFC电堆的输出电压.仿真结果表明,所建模型能较好地反映PEMFC的动态性能.与PID控制器相比,自适应模糊PID控制器可以使电池的输出电压快速平滑地过渡到设定值.     

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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