具有Friction边界条件的Navier-Stokes方程的两重牛顿校正算法

基于压力投影稳定有限元方法,给出一个求解具有Friction边界条件的Navier-Stokes方程的两重牛顿校正算法.从获得的误差估计可以看出,如果细网格尺度满足h=O(H4),那么该两重牛顿校正算法与一重稳定有限元方法具有相同的收敛阶.与有关文献相比,该算法的计算效率更高.     

一类修正阻尼牛顿算法

对一般目标函数极小化问题,提出一类新的修正阻尼牛顿法.若Hessian矩阵正定且目标函数梯度不为零,则搜索方向取牛顿方向;若Hessian矩阵不正定且非奇异,且目标函数梯度的转置和牛顿方向的数量积大于零时,搜索方向采用负牛顿方向;若Hessian矩阵奇异或者目标函数梯度的转置和牛顿方向的数量积等于零时,搜索方向则采用负梯度方向.因此该算法能保证搜索方向始终为下降方向,并证明对一般的非凸目标函数,该算法全局收敛.     

解非线性方程的免导数牛顿算法

通过函数值的运算近似牛顿法中的导数项,构造了一个免导数的牛顿法.该算法与牛顿法一样,具有二阶收敛速度,但不需要用到函数的导数.通过与二分法结合,实现该算法的全局收敛性.数值结果表明该算法是有效的.     

改正的牛顿迭代法

给出一种改正的牛顿迭代法,证明了其是二阶收敛的,数值例子表明,改正的牛顿迭代法的迭代速度优于牛顿法及弦截法。     

数值分析中牛顿迭代法的引入方法探讨

数值分析中牛顿迭代法是求解非线性方程的基本方法.与一般教材上牛顿迭代法的引入方法相比,用积分方程引入牛顿迭代法更能体现数值计算中的＂近似＂和＂构造＂思想,便于进一步介绍牛顿法的各种改进形式,有利于学生＂创新＂算法能力的培养和创新意识的形成.     

几种修正拟牛顿法的比较

拟牛顿法是所有利用一阶导数求解无约束优化问题的方法中最有效的一类计算方法,如何提高实际计算中的运算效率,如何使得对非凸目标函数保持局部超线性收敛的同时具有全局收敛性,是对拟牛顿法进行研究的两个方向.对近年来相关文献的几种修正拟牛顿法进行分析比较,并提出和分析了一个修正BFGS拟牛顿法的收敛性.     

一类等式约束优化问题的改进牛顿算法

提出了牛顿方法与预优广义共轭梯度方法相结合的方法(简称为Newton-PGCG)求解库恩-塔克方程组。给出Newton-PGCG算法中预优广义共轭梯度法中预优阵的选取问题及其步数参数的确定原则，并在保证牛顿方法恰二阶收敛的条件下，证明了此算法也具有恰二阶收敛的优点。     

求解非线性方程组的改进牛顿法

对传统牛顿法进行了改进,提出了求解非线性方程组的改进牛顿法。在一定的假设条件下,证明了该算法的全局收敛性和超线性收敛。     

一个八阶收敛的修正牛顿法

给出了一个求解非线性方程的新算法,并证明了它具有八阶收敛速度。同时给出数值试验,通过与牛顿法及其他算法比较,说明了新算法具有一定的优越性。     

一类具有五阶收敛的牛顿改进法

利用牛顿定理,给出了一类具有五阶收敛的牛顿迭代改进方法,讨论了它的收敛性和误差估计,并给出数值算例。     

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,     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

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…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.