具有时滞和阶段结构的捕食系统的分析

建立了一类具有时滞和阶段结构的捕食系统。首先分析了系统的非负不变性、边界平衡点及正平衡点的局部稳定性;其次讨论了边界平衡点的全局渐近稳定性。当时滞τ由0变化到τ0时,系统在平衡点附近发生Hopf分支,即当τ增加通过临界值τ0时,该系统从正平衡点处分支     

一类具有阶段结构和时滞的捕食者-食饵模型分析

研究一类具有时滞和阶段结构的捕食食饵系统.通过对特征方程的分析得到了正平衡点及边界平衡点的局部稳定性,进一步地给出了当τ增加到τ0时,系统在正平衡点附近产生Hopf分支.最后,对保持稳定性的时滞长度进行了估计.     

一类具有阶段结构的捕食-被捕食系统的渐进性质

文章研究了一类具有时滞和阶段结构的捕食与被捕食系统.讨论了系统的正不变集,非负平衡点的渐进性及持久生存性.证明了当时滞τ很小时,系统在正平衡点是局部渐进稳定的,当τ增加到τ0时,系统在正平衡点附近产生Hopf分支。     

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.     

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.     

具有收获和Beddington-DeAngelis功能反应的捕食-食饵模型

研究食饵具有阶段结构,捕食者具有收获和时滞的Beddington-DeAngelis功能反应的捕食-食饵模型.选取合适的收获率,通过分析相应平衡点处的特征方程,得到各平衡点局部渐近稳定的条件.以时滞τ为分支参数,运用Hopf分支理论,得到当τ经过临界值τ₀时系统出现Hopf分支.最后,用Matlab软件进行数值仿真,并验证结论的正确性.     

时滞捕食系统的全局稳定性与Hopf分支

考虑具有追捕时滞与捕食者成熟期时滞的双时滞捕食系统.通过分析特征方程根的情况,得到平衡点的局部稳定性与Hopf分支产生的充分条件.运用迭代方法与比较原理研究了正平衡点全局吸引的充分条件.     

具有时滞的Logistic模型的分支问题的频域分析

研究一类具有时滞的Logistic模型。运用频域法并分析该模型对应的特征方程,得到了系统Hopf分支点,通过选择时滞τ作为参数,发现当参数通过某一临界值时,Hopf分支产生,Hopf分支产生,同时得到了系统正平衡点稳定的时滞范围处于零与某个正常数之间,数值模拟验证当时滞τ=τ0时,系统的正平衡点是局部稳定的,当τ>τ0时,系统的正平衡点是不稳定的。     

一类捕食与被捕食系统的渐近性

考虑了具有第Ⅱ类功能性反应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、全局渐近稳定性和持久生存性．当时滞τ很小时,系统在正平衡点是局部渐近稳定的,当τ从0增到τ0时,系统在正平衡点附近产生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.     

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     

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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