一类三阶非线性控制系统的概周期解

本文研究了一类三阶非线性控制系统（１）的一致概周期解的存在性，得到了简洁的充分条件，并对保证有一致概周期解存在的参数范围及其与系统系数间的关系作出了估计。     

吕卡提方程的周期解

本文研究带周期系数的吕卡提方程的周期解.当A(x)>0时,结出一个存在周期解的充分条件,指出秦元勋所著《周期系数的吕卡提方程的周期解》一文中的示性方程在[0,2π]上不处处有解时,仍可能存在周期解.例1说明了这一点,同时给出了周期解不存在的充分条件,它比上文中相应的条件弱.     

自适应鲁棒控制系统研究

本文提出了一种自适应鲁棒控制方法,该方法在一般鲁棒控制系统结构的基础上,将鲁棒控制器中的部分增益矩阵改为在线调整的自适应增益,使得自适应机构在系统出现大误差时作用、小误差时切除,并在保留了常规鲁棒控制系统的优良品质之前提下,进一步改善了这类系统的动态品质、提高了鲁棒性.文中给出了相应的定理,分析了各变量的有界性,并进行了实时仿真.     

Young measures generated by a class of integrands: a narrow epicontinuity and applications to Homogenization

Given a subset E of convex functions from into which satisfy growth conditions of order p>1 and an open bounded subset of , we establish the continuity of a map μΦ_μ from the set of all Young measures on equipped with the narrow topology into a set of suitable functionals defined in and equipped with the topology of Γ-convergence. Some applications are given in the setting of periodic and stochastic homogenization.     

Generalized One-Sided Laws for the Larger Observations of a Triangular Array

Consider independent and identically distributed random variables {X,X _nj , 1jn,n1} with density f(x)=px ^–p–1 I(x1), where p>0. We show that there exist unusual generalized Laws of the Iterated Logarithm involving the larger order statistics from our array.     

Soft almost disjoint families

An almost disjoint family is said to be soft if there is an infinite set that meets each in a nonempty but finite set. We consider the associated cardinal invariant defined to be the minimal cardinality of an almost disjoint family that is not soft. We show that this cardinal coincides with J. Brendle's cardinal .

     

一类含扩散与时滞的竞争型Lotka-Volterra系统的周期解

研究一类含扩散与周期时滞的生态模型,通过特征值问题以及模型自身的特点来构造上下解,应用比较原理得到了周期解存在与全局渐近稳定的一个充分条件.     

可定向闭曲面上最大阶保定向周期映射的唯一性

A．Wiman和W.J.Harvey证明了在亏格为g,g≥2的可定向闭曲面上，保定向周期自同胚的最大阶是4g 2。本文中我们研究了这样的映射的唯一性。我们证明曲面的自同构群的由这样的映射生成的4g 2阶循环子群在共轭意义上是唯一的。     

On the dimension of almost -dimensional spaces

Oversteegen and Tymchatyn proved that homeomorphism groups of positive dimensional Menger compacta are -dimensional by proving that almost -dimensional spaces are at most -dimensional. These homeomorphism groups are almost -dimensional and at least -dimensional by classical results of Brechner and Bestvina. In this note we prove that almost -dimensional spaces for are -dimensional. As a corollary we answer in the affirmative an old question of R. Duda by proving that every hereditarily locally connected, non-degenerate, separable, metric space is -dimensional.