泛函微分方程的Lipschitz稳定性

本文利用文[1][2]的思想方法,提出了泛函微分方程的(变分)LipschitZ稳定性的若干概念,并借助于积分不等式以及线性(或非线性)常数变易公式,讨论了泛函微分方程的(变分)Lipschitz稳定性,获得了若干新的结果.1.设D为R×C的子集,f:D→R~n是给定的函数,考虑泛函微分方程x′(l)=f(l,x_l)(l.1)x_t_0=φ_0,-r≤θ≤t_0·1.首先,我们给出泛函微分方程的各种(变分)Lipschitz稳定性的定义:定义1.1 称方程(1.1)的零解是Lipschitz一致稳定的,如果存在常数M>0,δ>0,使     

T.A.Burton定理的拓广

设r>0为一给定常数,C_n=C(〔-r,0〕,R~n).对φ∈C_n,定义‖φ‖=sup|φ(s)|,对任意给定常数H>0,记C~H_m考虑泛函微分方程(t)=F(t,x_t,y_t)(1)■(t)=G(t,x_t,y_t)其中F∈C(t, 0, 0)=0,G(t, 0, 0,)=0_0本文证明文的主要定理中,李雅普诺夫函数沿方程的解的导数关于状态变元(x,y)的定负性条件,可用李雅普诺夫函数沿方程的解的导数仅关于部分状态变元y的定负性条件代替.     

一类积分微分方程周期解的全局渐近稳定性

利用Lyapunov泛函方法讨论一类积分微分方程x^.(t)＝gradG(x(t)) f(t,∫-r0H（s)x(t s)ds)的周期解的全局渐近稳定性，得到其简便的判别方法。     

Lurie型的中立型泛函微分方程的绝对稳定性

§1.引言本文用李雅普诺夫泛函的方法建立下面两类Lurie型的中立型泛函微分方程的绝对稳定性的充分性判据. 一类是直接控制系统这里C是[-h,0]→R~n的连续函数全体的集合,其中的模定义为,x_t∈C,即x_1(θ)=x(t θ)(-h≤θ≤0).D(·):[t_0, ∞)×C→R~n.记I≡[t_0, ∞),     

滞后型泛函微分方程可反向延拓的充要条件

本文使用文[1]的有关符号和概念.考虑滞后型泛函微分方程x=f(t,x_t) (1)x∈R~n,x_t∈C=C([-r,0],R~n),r>0,f(t,φ):Ω→R~n”连续,Ω是 R×C 中的开子集,且设 f_φ~″和 f_φ~′在Ω中连续定义(?):[-r-α,0]→R~n,0<α相似文献   

一个具有弱奇异核的积分-微分方程的适定性问题

对下述Cauchy问题:解的适定性问题用丰群的方法讨论,其中函数g满足如下的条件: (Ⅰ)g及其导数[-r.0)上连续; (Ⅱ)当θ∈[-r,0)时,g(θ)>0,g′(θ)>0; (Ⅲ)lim g(θ)=+∝且∫_(-r)~ 0g(θ)dθ<∝.问民(*)是一个具有弱奇异核的积分-微分方程,同时也是非原子的中立型方程,最后得到的结果是:向题(*)存在唯一的连续解并且零解一致稳定。     

具有障碍的二阶Hamilton系统的周期解

二阶Hamilton系统:-=f(t,x)满足初始条件x(t)≥0,t∈R,且当x(t0)=0时,(t0-)=(t0+)=,在一定条件下,等价于系统{-=f(t,|x|)sgn(x),x(0)-x(2π)=(0)-(2π)=0{-=f(t,|x|)sgn(x),x(0)-x(2π)=(0)-(2π)=0本文使用非光滑情形下的一个新临界点定理得到系统(Ⅰ)或(Ⅱ)的一个周期解,进而得到二阶Hamilton系统的一个满足所述初始条件的解的存在性定理.     

脉冲泛函微分方程稳定性的新准则

研究了脉冲泛函微分方程 x'(t)=F(t,x(·)), t≥ 0, t≠ tk,Δx(tk)=I(tk,x(t-k)), k=1,2,.... 的稳定性.采用Liapunov泛函方法和Jensen不等式,通过改进Lyapunov泛函的下界,获得了这类方程的零解一致渐近稳定的新准则,改进了已有文献中的相应结果.     

关于Lotka-Volterra型积分微分方程解的渐近状态

本文考虑形如(t)=diag(x(t)){diag(b)x(t)+(integral from n=-r to 0([dμ(s)]x(t+s)}的Lotka-Volterra型积分微分方程,给出了这类方程的所有正解收敛于零或者发散到无穷的充分条件.     

抽象泛函微分方程解的存在性

设X是一Banach空间,r≥0,f:Ω(?)R×C([-r,0],X)→X考虑泛函微分方程x’(t)=f(t,x_t).主要结果指明:若f满足一定集压缩性条件,则初值问题“x’(t)=f(t,x_t),x_ο=(?)”有解.所用的主要工具是Kuratowski非紧测度.     

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