一个三阶自治混沌电路的分析

对一个三阶自治电路进行了研究，建立了数学模型，并根据模型对其进行了仿真研究，分析形成混沌的过程。用分岔控制方法实现了混沌的控制，对受控系统做出了控制参数的系统分岔图，由分岔图可以得到控制到np的周期轨道的取值范围，在这些范围内适当选择数值，将电路系统控制到1p，2p等周期轨道，并且只需将系统的单个状态变量反馈到系统的一个子系统就可以达到控制的目标，在电路中比较容易实现。     

利用非线性反馈控制Henon混沌系统的低周期态

对混沌系统实施有效控制是利用混沌的重要环节,提出1种利用非线性反馈控制Honen系统混沌运动的方法．根据混沌系统稳定性理论,确定反馈系数的取值范围;利用描绘系统分岔图和计算Lyapunov指数数值研究方法,验证理论分析的正确性．采用连续控制不仅可以实现不动点的镇定,而且可以将混沌系统控制到二周期态;使用间歇控制可以将混沌系统控制到三周期态．该方法控制目标明确,反馈增益的取值范围容易确定。     

一个新超混沌系统及其控制

用时间响应图和分岔图分析了一个新的超混沌系统由周期运动到超混沌运动的转迁过程,发现该超混沌系统具有丰富的动力学行为。推广了一种控制方法,即x∣x∣控制方法也可以将超混沌运动控制到稳定的周期轨道。     

一类非线性周期振荡电路的混沌控制

基于基尔霍夫定律建立了一类非线性周期振荡电路的数学模型,利用分岔图和Lyapunov指数谱分析了周期激振力改变时对系统动力学行为的影响,准确的刻画出系统的周期运动和混沌运动,揭示了此类系统倍周期分岔通向混沌的过程与系统的动力学行为的复杂性.利用Poincaré映射图分析了系统混沌吸引子的特性,通过Kaplan-yorke猜想,计算了系统的不同的混沌吸引子在时间序列的分数维.最后应用两种有效的反馈控制方法对此类非线性电路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,这两种控制法都可以将系统控制到稳定的周期轨道.     

上田振子系统的混沌及其混沌控制

研究了上田振子系统的混沌及控制方法,分析了该系统的动力学特性,给出了Poincare截面图、时间响应图及随系统单个参数变化的分岔图和Lyapunov指数图,采用反馈线性化方法来控制该系统的混沌.在不稳定平衡点数值仿真表明,设计线性反馈控制器可以将混沌控制到稳定的周期轨道.     

Sprott-F系统的混沌控制研究

利用非线性动力学理论,讨论了改进的Sprott-F系统的混沌特性.在参数区b E[0,0.5]上,利用全局分岔图,Lyapunov指数谱准确的表征了系统在此区间内的丰富的非线性行为.应用时滞反馈法、比例微分器控制法和x|x|法对系统的混沌控制进行了详尽全面的理论分析和数值模拟.结果表明,选择适当的反馈系数,通过以上三种控制法,可将系统的混沌运动控制到稳定的低周期状态.     

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.     

一类Mathieu方程的混沌控制

用数值方法揭示了非线性Mathieu方程的分岔现象和混沌行为。利用全局分岔图揭示了系统通向混沌的途径,并利用相图、响应图和Lyapunov指数图来分析系统的动力学特性。通过分岔图来选择适当的控制参数,利用耦合反馈控制和x|x|控制两种控制方法将系统的混沌行为有效地控制到不同的周期轨道。     

扁锥壳结构的分岔研究

利用伽辽金法建立了考虑薄膜张力的扁锥壳结构的动力学方程,利用系统的相图和Poincare映射图分析了系统的分岔行为和混沌形成过程.利用直接变量反馈控制方法实现了系统混沌的控制,将系统的混沌行为利用适当的控制强度控制到稳定的周期轨道。     

时滞反馈法控制一个自治混沌系统

利用非线性动力学理论,讨论了带有一个三维自治系统的混沌特性.利用数值方法得到系统在参数取不同值时的混沌吸引子和周期态.在区间a∈[0.05,0.3]上,利用全局分岔图和庞加莱截面图准确地表征了系统在此区间内的丰富的非线性行为.通过局部放大的全局分岔图发现,系统发生了倍周期分岔和倒倍周期分岔现象.最后,应用延迟反馈法对系统的混沌运动进行了控制,结果表明,通过此控制法可将系统的混沌运动控制到稳定的周期运动状态.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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