三阶段时滞种群生长模型的渐近稳定性

根据种群生长的阶段性,引入时滞建立了一类三阶段结构的时滞种群生长模型:{_1(t)=αx_3(t)-γx_1(t)-αe~(-γτ)x_3(t-τ)_2(t)=αe~(-γτ)x_3(t-τ)-bx_2(t)-αx_2(t),_3(t)=ax_2(t)-cx_3(t)-dx_3~2(t),初始条件:{x_1(t)=φ1(t)≥0,x2(t)=φ_2(t)≥0x_3(t)=φ_3(t)≥0,t∈[-τ,0]。利用微分方程稳定性理论分析了系统的零平衡点和正平衡点的局部稳定性。利用有效的Liapunov函数得到零平衡点和正平衡点的全局稳定性:1)当aαe~(-γτ)(b+a)c时,系统有唯一平衡点E_0,且它是局部稳定的;当aαe~(-γτ)(b+a)c时,E_0是不稳定的,此时系统除了E_0外,还存在唯一正平衡点E_*,且它是局部稳定的。2)当αe(-γτ)≤c,则系统的平衡点E_0是全局渐进稳定的,当αe~(-γτ)≥(a+b/a-b)c,ab,则系统的正平衡点E_*是全局渐进稳定的。所得结论对人工控制种群的发展具有一定的指导意义。     

一类捕食者具有传染病的时滞生态模型

研究了一类捕食者内部传播疾病且带时滞的捕食系统.分析了非负不变集、边界平衡态和正平衡态.当时滞τ足够小时,无病平衡点和正平衡点是局部渐近稳定的,随着时滞的增加,将产生Hopf分支.     

一类捕食者具有传染病的时滞生态模型

研究了一类捕食者内部传播疾病且带时滞的捕食系统.分析了非负不变集、边界平衡态和正平衡态.当时滞τ足够小时,无病平衡点和正平衡点是局部渐近稳定的,随着时滞的增加,将产生Hopf分支.     

具有时滞的食饵-捕食者模型的分支问题

研究一类具有时滞和比率依赖型功能反应函数的食饵-捕食者模型的动力学行为,分析表明系统的渐近稳定关键依赖于时滞.通过选择时滞作为参数,分析了系统从正平衡点处产生极限环的Hopf分支问题,同时得到了系统正平衡点稳定的时滞范围为0＜τ＜τ+,给出数值模拟验证了作者所得结果的正确性.最后给出本文的主要结论:当τ∈[0,τ0)时...     

一类具有时滞的传播系统的渐近稳定性

建立了一类含分布时滞的革新传播系统,研究了分布时滞传播过程的影响,讨论了持久性与正平衡点的存在性和唯一性及其局部与全局的渐近稳定性.证明当分布时滞的核函数取弱核形式时,平衡点是绝对渐近稳定的.     

一类时滞人口模型的全局吸引性

给出了保证时滞人口模型N＇(t)=r(t)N(t)1-N(t-τ)/1-λN (t-τ),t≥0的每一正解N(t)趋于正平衡点N*=1(t→∞)的一族充分条件,改进了相关文献中的一些结论.     

带有扩散和时滞的捕食与被捕食模型的稳定性与Hopf分支

本文考虑一类带有扩散和时滞的捕食与被捕食模型,分析了系统的非负不变性,边界平衡点性质及全局稳定性.在这一系统中,当时滞τ=τ1 τ2适当小时,正平衡点是局部渐近稳定的,随着时滞的增加,正平衡点由稳定变为不稳定,系统在平衡点附近发生Hopf分支.     

一类具有时滞的捕食与被捕食系统的渐近性

研究了一类具有时滞的捕食与被捕食系统,分析了系统的正不变集、边界平衡点性质和全局渐近稳定性及持久生存性.当时滞很小时,得到了系统在正平衡点是局部渐近稳定的充分条件,当τ增加到0τ时,系统在正平衡点附近产生Hopf分支.     

具有多时滞捕食-被捕食流行病模型的稳定性

考虑传染病对捕食-被捕食者都具有致病作用的一类时滞捕食-被捕食模型,分析了系统的非负不变性、边界平衡点的性质和全局稳定性,证明了当时滞u=τ1+τ2适当小时,边界平衡点E3是局部渐近稳定的,随着时滞的增加, E3由稳定变为不稳定,系统在E3附近发生Hopf分支;当时滞τ1+2τ2充分小时,边界平衡点E2=(1,0,0)是全局稳定的.     

含时滞导数项的高阶中立型微分方程的正周期解

研究了高阶中立型时滞微分方程dn'dtn(u(t)-cu(t-δ))+M(u(t)-cu(t-δ))=f(t,u(t),u′(t-τ(t)),…,u(n-1)(t-τ(t)))正ω-周期解的存在性.通过构造一个特殊的锥,运用锥上的不动点指数理论,获得了该问题正周期解存在性的结果.     

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.     

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.     

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