二阶奇异周期边值问题解的存在性和多重性结果

本文利用格林函数的正性和Krassnoselιskii不动点定理建立了周期边值问题u' ρ2u=f(t,u),u(0)=u(2π),u'(0)=u'(2π)和-u' ρ2u=f(t,u),u(0)=u(2π),u'(0)=u'(2π)的正解的存在性和多重性结果.     

二阶奇异周期边值问题正解的存在性和多重性

研究了二阶奇异周期边值问题u（″t）＋a（t）u（t）=f（t,u（t））,t∈[0,ω],u（0）=u（ω）,u（′0）=u′（ω）正解的存在性,当允许f（t,u）在u=0和u=c（c〉0）同时奇异时,用锥映射的Krasnoselsk ii不动点定理获得了其正解的存在性和多重性结果.     

实数上限拓扑空间

实数上限拓扑空间u是拓扑学的一个重要反例.在拓扑学中,很多重要结论都要用到它,因此研究u的性质,对我们澄清一些易混淆的错误观点具有非常重要的作用.重点分析拓扑空间u的连通性、可数性和正规性.     

一个非线性三阶微分方程的三个正解

利用LeggettandWilliams定理证明了非线性三阶常微分方程两点边值问题u +f(u) =0 ,u(0 ) =u′(0 ) =0 ,u(1) =0的三个正解的存在性     

非线性退缩抛物型方程的正解

考虑退缩抛物型方程ut=In(1 u)(Δu u)的初边值问题，得出了解的存在性和非负性。     

复合函数单调性的判断

y=f[g（x）]型函数可以看作南两个函数y=f（u）和u=g（x）复合而成,一般称其为复合函数。其中y=f（u）为外函数,u=g（x）为内函数。若内、外函数的增减性相同,则原复合函数为增函数;相反则为减函数,即复合函数,单调性遵从同增异减的原则。在做题过程中,     

一类四阶波动方程的弱解

研究下列初边值问题:utt αΔ2u-bΔut ututr g(u)＝0 in Ω×(0,∞);u(x,0)＝u0(x),ut(x,0)＝u1(x,0),x∈Ω;u＝(u)/(υ), x∈Ω的整体解的存在性和不存在性,以及整体解的惟一性和能量估计.这里Ω是Rn(n≥1)中的有界区域.借助于乘子方程,推出了整体解的能量衰减率.借助于势井理论,得到了在有限时刻内爆破的充分条件.由Galekin 近似方法得到解的存在性.     

关于带第一特征值λ1具Sobolev临界指数2^＊的一类椭圆方程—△u=λ1u＋｜u｜^2^＊—2u＋τ（x,u）

给出了半线性椭圆方程-△u=λ1u |u|^2^*-2u τ(x,u)的Dirichlet问题在对扰动项τ（x,u）增加适当条件后非平凡解的存在性定理，以及方程-△u=λu-|u 2^*-2u h(x),λ∈[λ1,λk]（这里λk是方程-△u=λu的第κ个互不相等的特征值）的非零解的存在性定理。     

三阶非线性微分方程正解的存在性

证明了非线性三阶微分方程u″′ a(t)f(u)=0满足下列条件之一：u(0)=0,u′(0)=0,u(1)=0;u(0)=0,u(0)=0,u′(1)=0;u(0)=0.u′(0)=0．u″(1)= 0;u(0)=0．u″(0)=0,u′(1)=0;u(0)=0,u″(0)=0,u′(1)=0;u(0)=0,u′(0)=0,u′(1)=0;的两点边值问题正解的存在性只需f(u)于两个端点u=0和u= ∞处或是超线性的,或是次线性的。     

一类二阶微分方程正解的存在性

本文借助锥不动点定理证明了带混合两点边值条件的二阶微分方程u‘ m^2u f(t,u)=0,αu(0)-βu‘(0)=0,γu(1) δu‘(1)=0正解的存在性．     

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!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.