一类具有脉冲作用与饱和治愈率的SIRS模型的分析

研究了一类具有出生脉冲,脉冲接种和饱和治愈率的SIRS传染病模型.首先研究了无病周期解和非平凡周期解的存在性和稳定性,得到了分支存在的条件,其次得到了一个Poincaré映射,运用Poincaré映射和中心流形定理讨论染病周期解的Flip分支.     

三维分片光滑Filippov-型方程Hopf分支周期解的数值计算

给出了三维分片光滑Filippov-型方程广义Hopf分支周期解的数值计算方法,通过在每个光滑区域内构造Poincaré映射,再计算复合的Poincaré映射的不动点得到了相应的广义Hopf分支周期解,并给出了数值算例.结果表明,算法是有效的.     

基于对角广义反射矩阵的线性微分系统及其周期解

为了解决具有对角广义反射矩阵的线性微分系统周期解与稳定性问题,采用通过广义反射函数寻找其Poincaré映射的方法.首先在广义反射函数定义下,给出可交换线性微分系统的反射矩阵的定义及广义反射矩阵的一般形式,得到具有对角广义反射矩阵的线性微分系统的广义反射矩阵,然后通过对角广义反射矩阵找到Poincaré映射,从而得到该类系统的周期解及稳定性,并推得二维线性微分系统的周期解与稳定性.由于广义反射函数解决周期解稳定性比其他方法具有很大的优势,所以,此种方法对研究相关微分系统周期解与稳定性具有一定的参考价值和指导意义.     

Riccati方程的广义反射函数与周期解

为了解决Riccati方程的周期解与稳定性,提出了通过Riccati方程的广义反射函数来寻找其Poincaré映射的方法。结果表明:从微分系统的广义反射函数角度出发,得到了Riccati方程具有线性广义反射函数的条件,从而推出了Riccati方程的线性广义反射函数,得到了Riccati方程的Poincaré映射,以及Riccati方程有周期解的条件与稳定性。由于通过广义反射函数寻找Poincaré映射比较简单可行,所以,Riccati方程的周期解与稳定性的研究成果对其它微分系统的研究也具有指导作用。     

具垂直传染的SIRS传染病模型的脉冲控制和分岔分析

本文研究一个具有脉冲生育、脉冲接种和垂直传染的SIRS传染病模型的动力学行为,给出超临界分岔发生的条件,得到了疾病流行与否的阈值.通过利用Poincaré映射和中心流形定理,讨论了地方病周期解的flip分岔,并给出能验证理论分析的数值结果.     

一类平面分段光滑系统的周期轨的存在性

首先利用光滑子系统的流建立了不连续边界上的截面映射,并将截面映射进行复合从而得到系统的Poincaré回归映射.进一步讨论后继函数的零点,得到系统存在非平凡周期轨的充分条件。     

基于指数型广义反射矩阵的微分系统与周期解

为了解决具有指数型广义反射矩阵的线性微分系统的周期解与稳定性问题,提出通过线性微分系统的广义反射矩阵来寻找其Poincaré映射的方法,研究了具有指数型广义反射矩阵的线性微分系统.x=P(t)x的条件,给出此类线性微分系统的广义反射矩阵的形式和广义反射函数,从而得到该类微分系统的周期解和稳定性.该结果对研究其他微分系统的周期解与稳定性具有一定的参考价值和指导意义.     

具有阶段结构的害虫-天敌模型的脉冲控制

研究了一类具有阶段结构的害虫-天敌系统。当使用杀虫剂消灭害虫时,研究脉冲形式的控制,得到了无天敌时系统存在稳定的周期解。然后利用分支理论,讨论害虫-天敌模型的非平凡周期解,周期解由稳定变成不稳定的。     

一类具混合功能反应函数的三种群捕食链模型分析

提出并研究了一类具有脉冲干扰和混合功能反应的三种群捕食链模型.得到系统存在半平凡周期解.通过脉冲微分方程的Floquet理论和小幅扰动方法,研究了半平凡周期解的局部稳定性.证明了系统所有解是一致最终有界的.最后给出了数值分析实例.     

一类带不变号权函数二阶超线性方程的周期碰撞解

运用相平面定性分析方法, 研究一类带不变号权函数二阶微分方程的碰撞问题. 通过坐标变换将碰撞问题转化为与之等价的定义在全平面上的问题, 在某种超线性条件下对解的动态行为进行分析, 得到了大振幅解的动态行为. 结果表明, Poincaré映射在充分大的圆环边界上具有扭转性, 并通过反复运用推广的Poincaré Birkhoff扭转定理, 得到了无穷多个ω- 周期碰撞解的存在性.     

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.     

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