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.     

鲁西北地区农民商业保险消费滞后的原因与解决对策

针对当前经济社会改革过程中农民生活的风险含量不断增大的事实,主要考证农业地区商业保险在农民规避风险中所起的作用,发现商业保险介入农民生活的力度还不强,由此分析其原因,并给出解决的对策。之所以选择鲁西北地区作为研究样本,是因为该地区农民以农业生产为主,属经济欠发达地区,与我国大部分农业地区的经济发展情况大体相当,对研究以农业生产为主的农村地区农民的保险消费情况具有一定的代表性。     

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.     

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。     

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。     

冷拉拔对LY12铝合金小棒组织和性能的影响

研究了淬火前不同冷变形量对ＬＹ１２铝合金挤压小棒组织和性能的影响．结果表明：不同的冷拉拔量对ＬＹ１２铝合金组织和性能有明显的影响；适当的冷变形量能减少或消除该合金挤压棒材的粗晶环．作者还对粗晶环的形成原因及其消除方法进行了讨论．     

杉木基因型遗传稳定性的空间模型分析

对来自南方１４个杉木种子园的１１２个优良家系在８个测试点进行了生长的遗传稳定性评定，在材积ＡＭＭ１模型分析基础上所作的空间分析结果表明，参试家系在生长性能和遗传稳定性方面有着明显的差异，但具广播稳定性且生长表现卓越的家系所占的比例较少，并且大多来自广西区种子园，因此在作家优良家系选择和推广时，必须先试验后推广，因地制宜。