单端初级电感变换器的分数阶建模与仿真分析

出于电感和电容本质上是分数阶的实际情况考虑，针对单端初级电感变换器(Single ended primary inductor converter, SEPIC)的分数阶建模问题进行研究，建立了更准确的分数阶模型。在分数阶微积分的理论基础上，使用状态空间平均法，建立了电流连续模式下SEPIC的分数阶数学模型，推导了分数阶模型的静态工作点、电感电流纹波、电容电压纹波和传递函数表达式。采用分抗电路拟合的方法，实现0.9阶电感和0.9阶电容，用它们替换变换器中的整数阶元件，得到了SEPIC的分数阶电路模型。在MATLAB/Simulink仿真软件中，对SEPIC的分数阶数学模型和电路模型进行了仿真，并与理论计算值进行比较，仿真结果与理论计算基本一致，充分验证了分数阶模型的正确性。对比了分数阶模型与整数阶模型的差异，分数阶模型会产生更大的纹波，但具有更好的动态性能：响应速度更快，超调量更小，到达稳态的时间更短。     

异步电机全分数阶矢量控制系统的设计与实现

为实现异步电机的高性能控制,提出了一种基于全分数阶PIλDμ控制器的矢量控制系统设计方法。根据分数阶控制器的数学特征,确定矢量控制系统中分数阶电流环控制器和分数阶电压环控制器的形式;根据相位裕量、幅值及增益鲁棒性准则求出分数阶控制器的参数;在数值仿真中,采用Oustaloup递归滤波器来实现分数阶算子的近似和有理化,对比了同样设计标准下整数阶控制器和分数阶控制器在横转速、转速变化和负载突变下的动态性能。对所提控制方法进行了实验验证,结果表明:相较于采用整数阶PID控制器系统,采用电流转速双闭环全分数阶PIλDμ控制器系统的跟随性能和抗扰性能更优,使用分数阶的矢量控制系统能使阶跃响应的超调量和调节时间分别下降24.84%和7.35%,在输入变化的系统中分数阶的动态降落为整数阶的22.5%。研究结果表明,所提分数阶控制器的设计方法可用于异步电机高性能矢量控制系统。     

基于分数阶微积分的模糊分数阶控制器研究

在分析分数阶微积分的基础上,提出了一种新型模糊分数阶比例积分微分控制器.分数阶微积分将传统控制器中的积分和微分的阶数扩展到任意实数,为控制器的设计提供了比传统整数阶更好的性能扩展.结合分数阶比例积分微分控制器和模糊控制逻辑,用分数阶比例积分微分单元代替传统的模糊比例积分微分控制器中的比例积分微分单元,构建了模糊分数阶比例积分微分控制器的结构,采用模糊逻辑推理和Tus-tin离散方法实现了模糊分数阶比例积分微分控制器的计算.最后,用数字仿真方法和不同条件下的对比分析验证了新型模糊分数阶比例积分微分控制器的优良控制特性.研究结果表明,设计的新型模糊分数阶比例积分微分控制器对非线性和参数不确定性具有较强的鲁棒性.     

分数阶混沌系统参数调制数字通信及电路仿真

利用自适应控制方法,给出了比整数阶混沌系统的动力学行为更为复杂的分数阶混沌同步控制器的解析式,并对其进行了理论研究以及实验仿真.基于参数调制原理,利用分数阶混沌系统,提出了一种数字通信方案,对电路进行了仿真,结果显示接收信息和发送信息符合完好,验证了所提方案的有效性和可行性.     

电机分数阶PI控制及DSP实现

为了提高永磁同步电机的转速控制性能,引入分数阶控制器.针对永磁同步电机电流和速度的双闭环系统,建立电机模型并推导其传递函数;根据Flat Phase原则,在电机速度环中设计分数阶PI~λ控制器,对分数阶控制器和整数阶控制器分别进行多种转速试验对比.试验结果表明,分数阶PI~λ控制器的控制效果要优于整数阶PI控制器,降低了电机转速的均方根误差,提高了电机的转速控制精度.     

无平衡点分数阶混沌系统的动力学行为分析及有限时间同步

针对整数阶动力系统无法描述实际生活中的一些复杂现象,分数阶微分方程对动力系统能够进行更准确、更有效的描述,且在众多高精尖领域被广泛应用。本文研究了一类特殊的无平衡点分数阶混沌系统,首先通过预测校准算法将整数阶系统转化到分数阶,并分析了该系统的基本动力学特性。其次应用分数阶有限时间稳定性理论设计控制器,对系统进行有限时间同步控制。最后通过数值仿真实验验证了所设控制器的有效性。     

电机位置系统的分数阶PID控制

采用了增益鲁棒规则设计了分数阶PID(FOPID)控制器,并对电机位置系统进行了仿真,仿真结果表明分数阶PID控制器的鲁棒性及动态响应性能要优于传统的整数阶PID(IOPID)控制器,从而验证了该控制器的有效性与合理性。     

基于占空比分配的交错并联Boost PFC仿真研究

传统交错并联Boost PFC电路的平均电流控制法基于均流控制,但实际应用中无法确保元器件的参数一致,无法实现均流控制;针对上述问题,提出了占空比分配法实现交错并联Boost PFC的均流,该方法将总电感电流平均值的1/2与各相电感电流平均值进行比较,根据比较后的结果确定各相的占空比;通过对电路各元件参数的计算,实现了400 V/200 W交错并联PFC电源的设计;最后,利用MATLAB进行仿真验证,仿真结果表明,所提出的占空比分配法能够实现输入功率因数高和两路电感均流。     

基于分数阶PI~λ控制器的单容水箱液位控制

讨论分数阶PIλ控制器在单容水箱液位控制中的应用问题,给出了一种基于图解稳定性准则的PIλ控制器的设计方法.研究了PIλ控制器的参数稳定域,然后在稳定域内进行系统性能的设计,并提出具体的设计算法.通过Matlab仿真和水箱液位控制系统的实际操作实验,对分数阶PIλ控制器、整数阶PI控制器和常规Ziegler-Nichols参数整定方法进行比较,说明了本文设计方法的有效性和分数阶PIλ控制器的优越性.     

基于分数阶微积分的风力发电机的变桨距控制方法研究

在分数阶微积分理论的基础上,研究了风力发电机变桨距液压控制系统控制策略,并运用Matlab的Simulink工具仿真,分析各个控制策略对风力发电机的变桨距液压控制效果。仿真结果表明,与整数阶PID控制器相比,该系统在分数阶PIλDβ控制器控制下整个闭环系统具备较好的动、静态性能,说明分数阶PIλDβ控制器控制性能的优越性。     

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     

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