一类NFDE全时滞渐近稳定的代数判据

本文给出了一阶 n 维中立型微分方程(t)+A(t-τ)+Bx(t)+Cx(t-τ)=0 (1)全部特征根为负的充要条件(对Vτ≥0)。特别地,对 n=1.2的情形,给出了(1)之解全时滞渐近稳定的代数判据。     

具周期系数时滞差分方程的全局渐近稳定性

考虑具周期系数非线性时滞差分方程xn 1-xn pnxn-k=pnf(x[n/τ]τ-l），n=0，1，2，…，其中{pn}为T周期正数列，即Pn τ=pn，k=sT，k，s，T为自然数，通过讨论对应的齐次线性差分方程的性质，获得了关于零解全局渐近稳定的充分必要条件。     

n阶常系数线性时滞微分方程无条件稳定的代数判据

本文给出了关于方程 (t)+sum from k-1 to n a_K (t)+sum from k-1 to n b_K X(t-τ)=0 对一切时滞τ≥0零解都是渐近稳定的一些等价的定理以及充分必要的代数判定准则。     

一类重尾分布下的随机游动及其在保险理论中的应用

研究了一类推广的随机游动即Sn=sum from i=1 to n Xi,其中Xi(i≥1),为一列独立同布的具有有限负均值的随机变量序列,Xi～F(i≥1),且-∞<μF<0.主要研究了F属于控制变化尾族时,P(Au>x)的渐近性质,其中Au=sum from k=1 to τοu Lk-u及τuο={n:τn=Tu},并应用其在保险理论中得到一些结果.     

τ-拓扑下的不动点定理

τ是X的一个线性H ausdorff拓扑,在一致τ-O p ia l或τ-UKK条件下,给出了渐近非扩张型映照的不动点定理.由于L1(μ)并不具备通常的O p ia l条件,但是在L1(μ)赋予抽象测度拓扑τ下,(X,τ)满足一致τ-O p ia条l件,从而给出L1(μ)中渐近非扩张型映照的不动点定理.     

Hopfield型时滞神经网络模型的K-稳定性

研究具有时滞的Hopfield型神经网络模型｛Cidui(t)/dt=-ui(t)/Ri n↑∑↑j=1～↑Tijfi(uj(t-τ）） Ii，ui（s）=ψi(s),s∈[-τ，0],i=1,2,…，n平衡点的K－全局渐近稳定性与K－全局指数稳定性，通过使用不等式分析技巧和微分方程性质，得到了这类模型K－稳定性的易于验证的时滞相关充分条件，并举例验证其有效性。     

n重迭代Brown运动关于球面的首中时与末离时的矩

设τi^(n),σr^(n)分别为n重迭代布朗运动关于球面的首中时与末离时，得到了Eτ^(n)与Eσr^(n)递推公式及一般公式。     

一类非线性时滞微分方程解的渐近性

研究非线性时滞微分方程x(t) n∑i=1 pi(t)f(x(τi(t))=r(t)的解的渐近性,得到了方程的所有解x(t)当t→∞的趋于0的充分条件,推广和改进了燕居让的结果。     

一类变时滞的中立型微分方程的稳定性

利用Lyapunov函数及不等式,研究了一类变时滞线性中立型微分方程[xi(t)-n∑j=1aijxj(t-τj)]’=bixi(t)+n∑j=1cijxj(t-δj(t))+n∑j=1dijxj(t-ξj)的稳定性,并得到该方程的零解渐近稳定的充分条件.     

一类时滞微分方程滞后量的估计

考虑时滞微分方程 x(t)=A(t)x(t)+B(t)x(t—τ)和 x(t)=A(t)x(t)+B(t)x(t—τ)+H((x(t),x(t-τ)),其中 A(t)和B(t)是n×n矩阵,关于t连续,H:R~?×R~?→R~?是非线性连续函数,是后一系统的扰动函数。本文中,对两个系统分别给出了滞后量的估计τ_0,使得当 0≤τ≤τ_0时,前系统渐近稳定,后系统在经常扰动下是稳定的。估计中运用了新的方法,因此,估计较少保守性。改进和推广了有关文献中的结果。     

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.     

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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