A SISO mixed H_2/l_1 optimal control problem and its solution

INTRODUCTIONOneofthemethodsforsolvingoptimalregu lationandtrackingproblemsinlinearsystemsistheH2 optimalcontrolscheme,wherethecon trollerminimizestheexpectedvalueofanH2normcriterion .Itiswellknown ,however,thattheperformanceoftheH2 optimalcontrollersmaybehighlysensitivetoparameteruncertainty(Doyle,1982 ) .ThisiswhyalternativemethodsthathavebeentriedmayprobablybesuboptimalwithrespecttotheH2 normcriterionofthenom inalsystemononehand ,butwillguaranteesomekindofrobustnesswithrespecttothelarg…     

解两类非线性微分方程的常数变易法

常数变易法是求解非齐次线性微分方程的一种有效方法。本文利用常数变易法来求解两类非线性微分方程,从而推广了有关文〔1〕、〔2〕、〔3〕、〔4〕、〔5〕、所研究的可解方程类型;同时还改进、简化了文(4)、(5)某些方程的求解方法。     

A SISO mixed<Emphasis Type="Italic">H</Emphasis><Subscript>2</Subscript>/l<Subscript>1</Subscript> optimal control problem and its solution

Study of the SISO mixedH ₂/l₁ problem for discrete time systems showed that there exists a unique optimal solution which can be approximated within any prescribed missing error bound inl ₂ norm with solvable suboptimal solutions and solvable superoptimal solutions. Project supported by the National Natural Science Foundation of China (No. 60174026) and the Scientific Research Foundation for Returned Overseas Chinese Scholars of Zhejiang Province (No. J20020546)     

Riccati方程的一个新的可解定理

本文研究著名的Riccati微分方程的解法,引入了对偶Riccati方程和特征常数的概念,得到Riccati方程的一个新的可解定理,推广了前人的可解结果,然后给出一系列新的实用的可解充分条件,使得求解某些Riccati方程的棘手问题得到满意的解决。     

可换四元数分析中广义正则函数的Riemann-Hilbert边值问题

研究了可换四元数空间的正则函数、广义正则函数,提出了它们的某些R iem ann-H ilbert边值问题,并得到了它们的可解条件,解的表示以及唯一性.     

双解析函数的线性共轭边值问题

本文研究双解析函数的线笥共轭边值问题 ,讨论可解性条件并得出解的封闭形式     

二阶方程y″ py′ qy=f(x)通解的公式解法

用常系数p、q及函数f(x)直接给出二阶常系数线性微分方程通解的求解公式,并由此直接推出含参数又的二阶线性微分方程的解法。     

例外簇元与集值互补问题

在文献［5-10］中Isac等人发现当多值互补问题无解时,与之相联系的映象一定存在一个序列满足一组条件,Isac等人称这个序列为例外簇,另一方面,当多值互补问题有解时,与之相联系的映象一定不存在例外簇。该文证明了几类互补理论所涉及的非线性映象没有例外簇元,并得出与之相联系的集值互补问题（MCP）是可解的。     

单位圆周上的周期Hilbert边值逆问题的研究

文章介绍了解析函数的周期Hilbert边值逆问题在单位圆周上的数学提法,应用周期延拓、保形变换等方法将问题转化为经典的Riemann边值问题和Hilbert边值问题,并依据它们的经典理论,讨论了此类边值问题的可解性,给出了该类边值问题的可解条件及其在正则情况下的一般解.     

例外簇元与集值互补问题

在文献［5-10］中Isac等人发现当多值互补问题无解时,与之相联系的映象一定存在一个序列满足一组条件,Isac等人称这个序列为例外簇,另一方面,当多值互补问题有解时,与之相联系的映象一定不存在例外簇。该文证明了几类互补理论所涉及的非线性映象没有例外簇元,并得出与之相联系的集值互补问题（MCP）是可解的。     

二阶非线性微分方程解的有界性

研究了一类二阶非线性方程解的有界性 ,并给出了方程一切解有界或一切解是L2 -解的充分条件     

Non-E 2 class of strongly nonlinear generalised R-H boundary value problems for second-order elliptic system

In this paper, a class of strongly non-linear generalised Riemann-Hilbert problems for second-order elliptic system is studied. By means of the theory of integral equations and using an explicit form of the solution, a reduction is made to a nonlinear boundary value problem for two holomorphic functions. And using an approximation dealing with a solvable perturbed problems and suitable prior estimates, we prove that the problems possess solution in Hardy class, the solution w(z) belongs to , p>2. Project supported by the National Natural Science Foundation of China (19671056) and Shanghai Scientific Foundation (96ZA14020)     

关于费马解的一个同余方程

设p为奇素数,a为整数,若ap-1≡(1mod p2),则a名为费马解。根据华罗庚给出的几个特殊的费马解,可以探求费马解的一般方法。利用初等方法及原根的性质研究同余方程xp-1≡(1modpl),l≥1的可解性,可以得到该同余方程的一切正整数解和费马解。     

一类二阶变系数微分方程的求解

研究了二阶变系数微分方程y″+P(x)y=Q(x),在适当条件下将其转换为二阶线性常系数微分方程,并得到其通解。应用该方法,可求出许多变系数微分方程的通解。     

可解BCI-代数(Ⅰ)(英文)

本文引进了BCI-代数的换位理想和可解BCI-代数等概念,并用换位理想刻划了p-半单BCI-代数和结合BCI-代数。进而解决了可解BCI-代数的构造问题。     

主理想整环上线性方程组的矩阵解法

利用主理想整环D上矩阵的初等变换理论确定了D上线性方程组可解的判别准则,并且对于D上可解的线性方程组结出了其解的结构和求解方法.     

一类可解子群的结构与Fuchs方程的可积性

给出了SL(3k,C)中一类特殊的具有两个生成元的可解子群的结构定理.由单值群的可解性与Fuchs方程的可积性之间的关系,研究环面上只有一个正则奇点的3k阶的Fuchs系统的可积性     

最高阶元素个数对有限群结构的影响

我们讨论了群的最高阶元素个数为4p2的有限群G,得到：设M（G）I=4p2,n=2p或者n=2P2,其中p是素数,则G是可解群．     

中立型方程振动的充分必要条件(英文)

我们讨论中立型时滞微分方程 这里得到了方程(1)的一切解振动的充要条件,解决了B.G.Zhang在文[1]中提出的问题(12)我们还得到了方程振动的充分条件。     

No one way: Differentiating school district leadership and support for school improvement

This article examines findings from a qualitative investigation of how school district administrators in four mid to large sized urban school districts (10,000–50,000) identify and address differences in school performance. The analysis explores the interaction between district policies and actions that centralize and standardize expectations for teaching, learning, and leadership, and those that lead to the differentiation of district support to schools depending upon their identified needs. The findings demonstrate variability in district orientation and capacity to understand school needs to improve performance, as well as in district strategies for actually differentiating support to schools. Differentiated assistance can focus both on strengthening implementation of district expectations in order to improve school performance, and on supporting experimentation with non-standard solutions to performance challenges that are not solvable through use of established programs and practices.