A Novel Polymethyl Methacrylate （PMMA）TiO2 Nanocomposite and Its Thermal and Photic Stability

A new kind of polymethyl methacrylate （PMMA）-TiO2 nanocomposite was synthesized through polymerization. The thermal and photic stability of this PMMA TiO2 nanocomposites were investigated. The as prepared samples were characterized by scanning electron microscopy （SEM）, UV-Vis spectroscopy, differential thermal analysis （DTA） and the photo-induced weight loss, The results show that the photostability of the PMMA-TiO2 nanocomposite is higher than that of the pure PMMA under UV-light irradiation, The weight loss of the pure PMMA reaches 30 % after 300 h UVirradiation, while the composite only 0.3% under the identical experimental condition. The glass transition temperature （TR） of pure PMMA is only 80℃, while the Tg of the composite reaches 258℃. Compared with pure PMMA, the thermal stability of the composite is greatly enhanced.     

PEAK COVARIANCE STABILITY OF A RANDOM RICCATI EQUATION ARISING FROM KALMAN FILTERING WITH OBSERVATION LOSSES

We consider the stability of a random Riccati equation with a Markovian binary jump coefficient. More specifically, we are concerned with the boundedness of the solution of a random Riccati difference equation arising from Kalman filtering with measurement losses. A sufficient condition for the peak covariance stability is obtained which has a simpler form and is shown to be less conservative in some cases than a very recent result in existing literature. Furthermore, we show that a known sufficient condition is also necessary when the observability index equals one.     

有限个一致李普希兹渐近拟非扩张映像强收敛定理

在任意Banach空间中,给出了有限个一致李普希兹渐近拟非扩展映像强收敛于其公共不动点的问题,此结果推广了以前的结论.     

东露天铁路专线采空区治理对策研究

针对东露天铁路专线所经过的采空区特点,分析了典型采空区上覆岩层的稳定性和上覆岩层移动形式,提出该地区采空区的治理措施。     

无缝线路稳定性探讨

从无缝线路稳定性研究意义、研究理论着手,分析探讨了影响稳定性的因素,提出提高无缝线路稳定性的措施。     

复系数区间系统的Hurwitz稳定性

将Hurwitz稳定性概念推广到复系数区间系统,并对二阶复系数区间系统的Hurwitz稳定性和Hurwitz不稳定性分别给出了2个充分条件,最后给出了一些实例说明结论的有效性.     

关于L——函数的积分均值公式

利用 Hurwitz zeta—函数的函数方程及其解析方法给 Dirichlet L—函数的二次均值的一个较强的渐近公式.     

一种由负定函数dV（x）／dt判定动态系统原点稳定性的方法

提出一种由负定导函数判定动态系统稳定性的方法，给出在已知导函数为负定的情况下系统稳定或者不稳定的充要条件，以及一组使用该方法的例子。     

部分线性模型的渐近性

考虑Ｙｉ＝Ｘ＾ｔｉβ＋ｇ（ｔｉ）＋εｉ，１≤ｉ≤，忱里Ｘｉ是一固定设计点列，ｔｉ是独立同分布随机变量并且服从［０，１］上均匀分布。