共查询到20条相似文献,搜索用时 46 毫秒
1.
梁伟 《四川大学学报(自然科学版)》1993,30(3):408-412
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 相似文献
2.
吴建宏 《湖南大学学报(自然科学版)》1987,14(1)
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. 相似文献
3.
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。 相似文献
4.
阮炯 《复旦学报(自然科学版)》1984,(1)
§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, ∞), 相似文献
5.
王克 《东北师大学报(自然科学版)》1984,(4)
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
6.
李平 《北京化工大学学报(自然科学版)》1992,(3)
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。 相似文献
7.
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. 相似文献
8.
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. 相似文献
9.
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. 相似文献
10.
胡适耕 《华中科技大学学报(自然科学版)》1993,(Z1)
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. 相似文献
11.
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. 相似文献
12.
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. 相似文献
13.
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。 相似文献
14.
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. 相似文献
15.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
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- 相似文献
16.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
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- 相似文献
17.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
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 相似文献
18.
《上海师范大学学报(自然科学版)》2014,(5):550
<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 相似文献
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20.
《吉林大学学报(理学版)》2014,(5):1105
<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has 相似文献