具有时滞的周期微分系统的周期解

考虑周期微分系统x·(t)=A(t,x(t-r1))x(t)+f(t,x(t-r2))的T-周期解的存在性问题,其中(t,x)∈R×Rn,A(t,x)是n×n连续矩阵函数,f(t,x)是n维连续向量函数,A(t+T,x)=A(t,x),f(t+T,x)=f(t,x),且T>0,r1,r2∈R.利用不动点方法,建立了保证系统存在T-周期解的充分条件,改进和推广了文[1～4]的相关结果.     

具周期贮存率的两种群竞争的Lotka-Volterra斑块系统的周期解

讨论具周期贮存率的两种群竞争的Lotka-Volterra时滞斑块系统：{x′1(t)=x1(t)[r1(t)-α1(t)x1(t)-b1(t)y(t)] D1(t)[x2(t)-x1(t)] S1(t) x′2(t)=x2(t)[r2(t)-α2(t)x2(t)] D2(t)[x1(t)-x2(t)] S2(t).y′（t)=y(t)[r3(t)-b2(t)x1(t)-α3(t)y(t)-β（t)∫-t^0k(s)y(t s)ds] S3(t)其中ri(t),αi(t)(i=1,2,3),Di(t),bi(t)(i=1,2)和β（t)均为正的连续周期函数，Si(t)(i=1,2,3）是非负连续周期函数。利用新的方法，得到了该系统正周期解存在的充分条件。我们的结果大大推广了相应的结果。     

周期系数的Riccati方程的周期解

本文提出了周期系数的Riccali方程存在周期解的一个充要条件,针对“示性方程”A(x)y~2+B(x)y+C(x)=0的“判别式”B~2(x)-4A(x)C(x)不定号情形,给出了一些新的判定方法,举例说明了本文结果的应用.     

具有变量时滞的高维周期系统的周期解

考虑高维周期系统x·(t) =A(t,x(t-r1(t) ) )x(t) +f(t,x(t-r2 (t) ) )的T -周期解的存在性问题 ,其中 (t,x)∈R×Rn,A(t,x)是n×n连续矩阵函数 ,f(t,x)是n维连续向量函数 ,时滞ri(t) (i=1,2 )是连续函数 ,且A(t+T ,x) =A(t,x) ,f(t+T ,x) =f(t,x) ,ri(t+T) =ri(t) (i=1,2 ) ,常数T >0 .利用不动点方法 ,建立了保证系统存在T -周期解的充分条件 ,所得结论推广了一些学者的相关结果     

离散logistic方程的伪概周期解

利用伪概周期函数的定义与性质得到了下列离散系统x(n+1)=α(n)x(n)/1+β(n)k(n) (1)正的伪概周期解的存在性的充分条件.这里,α(n)、β(n)都是伪概周期序列.     

离散logistic方程的伪概周期解

利用伪概周期函数的定义与性质得到了下列离散系统x(n 1)=α(n)x(n)/(1 β(n)k(n))正的伪概周期解的存在性的充分条件。这里,α(n)、β(n)都是伪概周期序列。     

一类二阶周期边值问题的正解

主要研究了具有奇异正定超线性周期边值问题正解的存在性问题,利用Leray-Schauder抉择定理给出了奇异正定超线性周期边值问题-(p(t)x′)′ q(t)x=f(t,x),t∈I=[0,1],x(0)=x(1),x[1](0)=x[1](1).(1.1)的正解的存在性,其中非线性项f(t,x)在x=∞点处超线性,在x=0处具有奇性。     

一类二阶周期边值问题的正解

主要研究了具有奇异正定超线性周期边值问题正解的存在性问题,利用Leray-Schauder抉择定理给出了奇异正定超线性周期边值问题{-(p(t)x′)′ q(t)x=f(t,x),t∈I=[0,1],/x(0)=x(1),x[1](0)=x[1](1).(1.1)的正解的存在性,其中非线性项f(t,x)在x=∞点处超线性,在x=0处具有奇性.     

一类高阶时滞微分方程的周期解

用重合度理论研究高阶时滞微分方程x(m) am-1x(m-1)(t-τm-1(t)) … a1(t)x′(t-τ1(t)) g(t,x(t-0τ)(t)))=0的周期解存在性,得到了该方程存在T(T>0)周期解的充分性定理。     

多时滞微分差分方程的周期解

文章研究多时滞微分差分方程x′(t) =-γx(t) f (x(t- 1) ,x(t- 2 ) ,… ,x(t- m) ) ,得到了方程存在非常数周期解的充分条件 ,推广了 Hadeler,Tomiuk相关的结论     

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.     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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