一个新混沌系统的Hopf分岔分析及其电路实现

通过非线性动力学理论,分析了一个混沌系统的平衡点的稳定性,对该系统的平衡点进行了Hopf分岔分析,得出Hopf分岔的参数条件.经过计算系统在平衡点的第一Lyapunov系数判断了分岔的方向及其稳定性.最后进行了仿真模拟与实际电路的设计,实验结果与理论推导吻合.     

超音速气流中受热壁板的非线性动力学分析

研究了超音速气流中受热壁板的非线性动力学行为.用规范型方法研究了受热壁板由于Hopf分岔产生的颤振.数值模拟验证了理论分析的结果.利用Runge-Kutta方法对系统进行了计算,给出了系统的相图、分岔图,发现该模型存在混沌运动.当系统参数变化时,该系统可经过倍周期分岔进入混沌或产生阵发性混沌.     

电动汽车非线性悬架系统混沌特性

在分析电动汽车非线性因素的基础上,建立八自由度非线性模型.在正弦路面激励下,得到系统动力学响应,计算分岔图、庞加莱(Poincaré)截面和最大李雅普诺夫(Lyapunov)指数.分析结果表明该系统存在混沌运动,并发现了系统通过周期、拟周期进入混沌运动的演化过程.计算分岔图特殊点处的悬架动挠度,发现利用悬架动挠度的变化,能较好地反映系统的动态行为发生的变迁.     

一个新混沌系统的混沌分析及电路仿真

提出了一种新型混沌系统,该系统与Lorenz,R sslor,Chen系统不同,每个方程含有一个非线性乘积项,该系统具有较复杂的动力学特性,利用理论推导、Lyapunov指数、功率谱图和相图验证该系统在适当参数下处于混沌运动,随后用数值模拟系统的全局分岔图、全局李雅普诺夫指数谱和庞加莱映射图准确刻画出系统的周期运动和混沌运动,揭示了该系统的全局分岔行为与混沌形成过程,给出运用非线性耦合同步方法实现混沌同步的条件,同时运用Lyapunov方法对所得的条件进行理论证明,运用数值仿真证实控制方法的有效性.最后,通过对实际电路参数的计算以及模型参数的理论分析,验证了实验结果与计算机仿真结果的一致性.     

一类非线性周期振荡电路的混沌控制

研究了一类非线性振荡电路系统的复杂动力学行为.基于基尔霍夫定律建立了一类非线性周期振荡电路的动力学方程.利用Poincaré映射图分析了系统混沌吸引子的特性,通过分岔图和Lyapunov指数谱揭示了此类系统由倍周期分岔通向混沌的过程,并且验证了该系统的分岔图与Lyapunov指数谱是完全吻合的.最后,通过非线性反馈控制方法对非线性电路系统中的混沌状态进行了有效的控制,结果表明,通过选取适宜的控制参数可以将系统控制到不同的稳定的周期轨道.     

类椭圆非线性迟滞隔振系统的动力学模型

应用类椭圆函数建立了非线性迟滞隔振系统的动力学模型，并导出了系统动力学模型的实用表达式.该模型由非线性刚度和非线性阻尼构造而成，模型中各个参数具有明确的物理意义，各阶刚度系数能很好地描述系统中存在的线性和非线性特性，而阻尼函数能很好地描述系统的迟滞和耗能特性.模型中含有待辨识的阻尼成分函数，该函数能反映系统中可能存在的高阶阻尼、粘性阻尼和干摩擦阻尼等各种阻尼成分.由于在模型中将阻尼项表示为位移的函数，因而减少了测量工作量，方便了数值计算.应用动力学模型重构了非线性迟滞隔振系统的恢复力-位移回线，结果表明理论回线与实验回线吻合得很好.     

带摩擦的Rikitake双盘发电机模型的混沌与同步

利用非线性动力学理论讨论了带摩擦的Rikitake双盘发电机模型的混沌特性.通过数值计算得到该模型的定态解,并分析了该定态解的稳定性.利用数值仿真,得到在一定参数和初始状态下的吸引子和分岔图.为了实现该系统的混沌同步,选用耦合同步法,并选择了合适的耦合参数进行数值计算和计算机仿真.结果表明,该系统快速地达到了混沌同步.     

Duffing隔振系统中的混沌特性研究

文章基于混沌隔振原理,利用Duffing系统在混沌状态下的特殊性能进行隔振,通过对周期激励Duffing系统的相图、全局分岔图、庞加莱映射图的分析,说明了混沌的存在,以及混沌运动与各参数之间的关系,并给出了特定Duffing系统的混沌隔振效果.     

一维复Ginzburg-Landau方程的分岔及其精确行波解

利用动力系统分岔理论,研究了一维复Ginzburg-Landau(CGL)方程的分岔及其精确行波解.通过行波变换将非线性发展方程转化为二维平面动力系统,利用定性分析的方法,得到了该系统在不同参数条件下的所有分岔相图.借助非线性偏微分方程的行波解与对应的常微分方程的轨道的关系,通过行波系统的首次积分,获得了一维CGL方程的所有有界行波解的显示参数表达式.     

含中间质量改进三参数隔振器动力学特性研究

通过在含X形机构非线性三参数隔振器中引入中间质量,提出一种改进三参数隔 振器并建立其理论模型 . 采用谐波平衡法得到隔振系统的稳态解析解,利用四阶龙格库塔法 和多体动力学软件 ADAMS验证其正确性 . 将力传递率作为评价隔振系统动态性能的技术指 标,与传统三参数隔振器以及含X形机构非线性三参数隔振器进行对比,结合工程实际,分别 给出3种类型隔振器在多频稳态激励下的时域位移响应,并进行对比研究. 分析了该隔振系统 的功率流特性以及能量特征,选择隔振系统部分关键设计参数进行影响因素分析 . 从动力吸 振器的角度,讨论了所提模型中非线性连接方式对其减隔振效果的影响. 计算结果表明,合理 选择中间质量可以在原隔振系统谐振频率附近形成一个反共振低谷,且系统固有频率向低频 移动,使隔振系统有效隔振频带变宽;相比于传统三参数隔振器和含X形机构非线性隔振器, 隔振系统在低频和高频的隔振性能均得到有效提升;通过力传递率评估设计参数,结果表明 各参数均存在最优值;将线性动力吸振器与接地X形机构连接,可进一步改善其减隔振效果.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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