一类微分方程单支θ-方法的稳定性分析

改进了文献[2]中的一些结论，得到了：（1）单支口方法是（0，0，q）一代数稳定的充要条件；（2）如果β，p，q中有一个等于1，则单支θ-方法不可能是（β．p，q）一代数稳定的；（3）若q=0，β≤（2θ-1）／θ^2，p≤β（θβ-1）则单支θ-方法是（（β，p，q）一代数稳定的。并对单支θ-方法的数值稳定性进行了一定的分析。     

分布式延迟微分方程BDF方法的稳定性分析

本文讨论了二阶BDF方法应用于一类分布式延迟微分方程的延迟依赖稳定性.首先依据文献资料,在参数平面上画出了解析稳定区域,其次获得了数值稳定区域包含解析稳定区域的必要条件,由此得到BDF方法的相容性结果,最后给出了数值例子.     

积分型延迟微分方程隐式欧拉方法的稳定性分析

讨论了隐式欧拉方法应用于一类积分型延迟微分方程的延迟依赖稳定性。首先依据文献资料,在参数平面上画出了解析稳定区域,获得了数值稳定区域包含解析稳定区域的必要条件,由此得到隐式欧拉方法的相容性结果,最后给出了数值例子。     

多滞量时滞微分方程数值方法的非线性稳定性

对具有多个滞量的非线性时滞微分方程给出了其理论解渐近稳定的充分条件及数值方法的非线性稳定性概念,证明了隐式Euler方法是所谓NCR2-稳定的。     

二阶延迟微分方程单支θ-方法的渐近稳定性

考虑二阶微分方程单支θ-方法的稳定性质,证明当θ=1时数值方法将保持此时滞系统解析解的稳定性。     

Runge—Kutta方法稳定性的代数条件

就求解常微分方程的Runge-Kutta方法引入了若干新的稳定性概念并给出了蕴涵方法稳定性的代数条件。所获结果不仅揭示了方法的线性与非线性稳定性间的本质联系,而且即适用于隐式方法又适用于显式方法,为构造高效稳定的数值方法提供了新的依据。     

线性连续切换正系统的渐近稳定性

主要讨论了含有不稳定子系统的切换正系统的一致渐近稳定性问题,建立持续驻留时间模型,利用多余正Lyapunov函数给出系统稳定性的充分条件,并计算出持续驻留时间的具体数值,进一步将此方法推广至切换区间正系统,并给出其鲁棒稳定的充分条件。     

偏微分方程组数值解奇异性特征分析

通过对动力学系统微分方程组解的特征研究 ,发现应用数值方法求解微分方程组的解时 ,其解的稳定性由初始条件、系统函数和迭代步长共同决定 .当三者取值合理时 ,将会产生混沌现象 ,否则将得不到稳定的数值解     

Lorenz系统的一个线性反馈控制

研究了Lorenz系统的混沌控制问题,利用线性反馈控制方法设计了一种基于状态变量的线性反馈控制器,通过变量x,y的相互作用实现了不稳定平衡点的稳定控制,并用李雅普诺夫方法证明了在混沌控制器作用下,控制系统的稳定性.数值仿真结果验证了混沌控制器的有效性和鲁棒性.     

奇异系统重置观测器的稳定性分析简

研究了奇异系统重置观测器的稳定性问题．通过构造李雅普诺夫函数。结合线性矩阵不等式和S-Procedure方法,给出了奇异系统重置观测器二次稳定和输入输出稳定的充分条件．最后数值算例表明了结论的有效性．     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

胡主席在印度,我却在中国

Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer.