非线性系统时变时滞和参数的在线联合估计

为了解决非线性系统的时滞和参数的在线联合估计这一问题 ,提出了一种基于遗传算法的非线性系统时变时滞和参数的在线联合估计方法。将遗传算法的二进制编码改进为十进制编码。对于系统输入带有纯时滞的非线性系统 ,采用改进的遗传算法对系统时滞和参数进行在线联合估计。此方法能够有效地在线联合估计非线性系统的时变时滞和参数 ,并具有一定的抗噪声能力。仿真实验结果验证了此方法的有效性     

四维L.C振子的超混沌系统的参数辩识与同步

针对系统参数不匹配下的两个超混沌系统间的同步问题，提出了相应的参数辩识方法和参数补偿方法。理论分析和数值模拟结果表明，使用改进的参数辩识方法并结合参数补偿，可以实现参数不匹配下两个L.C振子超混沌系统的同步。     

基于差分进化算法的辅助燃油系统燃油转输参数优化

为了选取和优化辅助燃油系统燃油转输参数,通过对差分进化算法进行改进,发展了辅助燃油系统燃油转输参数优化计算方法,对燃油转输参数方案进行了优化计算分析。结果表明:发展的改进差分进化算法对燃油转输参数方案的优化问题求解有效;与给定的燃油转输策略的计算结果相比,燃油转输参数优化方案可以保证双发运行情况下和单发运行情况下的性能最优。     

基于CPI的船载高功放水冷系统改进设计

在雷达应用中,冷却系统是整个发射系统不可或缺的组成部分.对于船载雷达系统而言,水冷方式与其他冷却方式相比有着更好的效能比和应用价值.通过对船载大功率放大器水冷系统工作现状以及其局限性的分析,提出了改进方法.以现有设备为依托、以设备主要的参数指标为依据,从工作原理、流量计算、控制保护系统的设计改进等几方面详细描述了整个改进方案,并指出了一些需要注意的关键环节和细节问题.以船载高功放水冷系统为原型,对各类雷达水冷系统的改进都有着一定的借鉴作用.     

中央空调冷却水系统故障诊断与排除

针对中央空调冷却水系统实际运行中出现冷却塔水盘溢水问题,通过对设备运行参数分析,计算冷却水系统运行时候水盘不溢水所需要的水头,以理论数据为依据,改进冷却水管路系统,增加进出水点的落差,解决了水盘溢水问题,保证冷却水系统正常运行。     

六自由度电磁跟踪系统位置参数求解算法的改进

为了获得精度较高、稳定性较好的六自由度电磁跟踪系统目标参数求解算法,在分析原参数求解算法误差产生原理的基础上,引入特征值和特征向量的概念,提出了一种结合特征向量法和单位指向矢最大分量跟踪法的改进算法来求解目标的位置参数,并对改进算法的稳定性进行了分析。通过数值模拟和实验验证,算法很好地解决了原跟踪算法在位置参数α、β角度较小区域将误差放大的问题,提高了算法的稳定性和系统定位计算的精度。     

具有连续分布时滞的切换分布参数系统反馈控制

本文针对一类具有连续分布时滞的切换分布参数系统的反馈控制问题进行了研究。通过构造切换Lyapunov-Krasovskii函数,利用Poincare不等式、Jensen不等式,采用线性矩阵不等式(LMI)方法,得到了该闭环系统渐近稳定的条件并设计了状态反馈控制器以及切换规则。和已有具有连续分布时滞的分布参数系统的结果比较,本文充分考虑了该类具有连续分布时滞的分布参数切换系统中Laplace算子系数对系统的影响。本文结果是已有具有连续分布时滞的分布参数系统反馈控制结论的改进和推广。最后,给出了数值例子说明所给设计方法的有效性和优越性。     

大系统的稳定性参数区域

本文利用部分变元稳定性理论研究大系统的稳定性参数区域,改进了叶伯英建立的辅助系统方法。     

大时滞系统全参数自适应预测控制策略

针对大时滞系统纯滞后时间长、参数时变的特点,提出一种基于改进的粒子群优化的自适应预测控制算法.利用改进的粒子群优化算法对时变大时滞系统模型的全部参数进行辨识,从而克服预测模型失配对系统控制性能的影响,并且将粒子群优化算法用于预测控制滚动寻优,有效解决系统存在约束条件下的最优值求解问题.仿真结果验证所提方法的有效性和优越性.     

遗传算法在系统辨识中的应用

基于遗传算法,采用改进的遗传算子,提出了一种辨识系统参数的方法,该方法能有效地克服有色噪声的干扰,获得系统参数的无偏估计。仿真结果说明了该方法的有效性。     

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