齐次型方程及其求解

对一阶常微分方程中的齐次方程的推广形式——齐次型方程进行了研究,并将齐次方程的“变量变换”法求解过程推广应用到齐次型方程,从而证明了齐次型方程是可积方程,得到了一阶微分方程的几种新的可积类型,其中也包括部分黎卡提方程和贝努利方程。     

齐次方程及其求解

通过对一阶常微分方程中的齐次方程的推广形式——齐次型方程进行研究,并将齐次方程“变量变换”法求解过程推广应用到齐次型方程,从而证明了齐次型方程是可积方程,得到了一阶微分方程的几种新的可积类型,其中包括部分黎卡提方程和贝努利方程．     

二阶变系数线性齐次微分方程的可转化条件

二阶常系数线性微分方程的可解性及解的结构已有详尽讨论。而对于变系数线性微分方程,除了几种特殊类型的方程可积分外,关于其可积类型的讨论仍是一个值得研究的课题。本文通过变量替换的方法,推导出二阶交系数齐次线性微分方程y″ P(x)y′ Q(x)y=0可转化为常系数微分方程或一些已知的可求解类型方程的充分条件。     

常微分方程几个新的可积类及其范畴

以极平凡的方法得到了一个二阶线性微分方程以及相应Ｒｉｃｃａｔｉ方程的新可积类，指出了这类二阶线性可积方程的范畴，并由此推出几个新的可积型，同时也指出相应前人的结果是其特例。     

一类新二阶非线性微分方程的可积判据

先通过类比名的Bernoulli方程，提出了一类新二阶非线性微分方程，然后对它引进特征方程的概念，给出了一个实用的可积充分判据及其通解的积分表达式；在退化情形下，导出了经典的二阶常系数线性非齐次微分方程的通解表达式及二阶变系数线性齐次微分方程的一个新的可积类型。     

变系数二阶线性齐次微分方程的可积条件

在变系数二阶线性齐次微分方程具有某种特殊解结构的情形下,进行了可积性判据研究,获得了这些方程可积的充分条件.     

常微分方程的一个新的可积类型

在一定的条件下，通过函数变换将形如“S’(y)y’ p(x)s^2(y) q(x)s(y) r(x)=0”的微分方程化为我们所熟悉的可积方程，得到一个新的实用的可积类型，推广了可积性结果,扩大了微分方程封闭求积的范围。     

一类新Riccati型方程的可积性及其应用

对一类新Riccali型微分方程，在平凡情形下，证明了它是可积的；在非平凡情形下，给出了可积的一个实用的充分判据及其通解的表达式。作为应用，导出了一类新二阶变系数线性齐次微分方程的可积性。     

一类可积的Riccati型方程

利用齐次微分方程变换u=y/x，给出一类可积的Riccati型方程。     

关于线性非齐次微分方程的“基本解组”

相对于线性齐次微分方程的基本解组，本提出了线性非齐次微分方程的“基本解组”的概念，证明了线性非齐次方程也存在“基本解组”，且得到了一个有用的结论。     

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.