Controllability results for a class of one-dimensional degenerate parabolic problems in nondivergence form

We give null controllability results for some degenerate parabolic equations in non divergence form on a bounded interval. In particular, the coefficient of the second order term degenerates at the extreme points of the domain. For this reason, we obtain an observability inequality for the adjoint problem. Then we prove Carleman estimates for such a problem. Finally, in a standard way, we deduce null controllability also for semilinear equations.      

假设检验中的三个问题及其思考

讨论了假设检验的教学和实践中可能会遇到的三个问题.分析得到三个结论:理论上原假设与备择假设可以任意设定,但实践中常常按照某种规则来设定;假设检验的两个常用的决策准则中,p值准则更精确,为决策者接受原假设提供了一个"风险"的度量;假设检验理论在处理利用样本推断总体的问题中是普遍有效的.     

基于伪类光超曲面奇点分类的教学研究

在微分几何的教学中,曲线,曲面理论是最主要的基础理论知识.欧氏空间中密切曲线在微分几何学中具有重要的研究价值.主要运用具有类光向量的费雷内标架讨论在四维Minkowski空间中与欧氏空间不同的一类特殊密切曲线(伪类光曲线)的一些几何性质,同时通过横截性原理给出了由伪类光曲线生成的伪类光超曲面的局部几何性质与奇点分类.     

Some remarks on quasilinear wave equations with null condition in 3‐D

In this paper, we give an alternative proof to the global existence result, which is originally owing to the pioneering work of Klainerman and Christodoulou, for the Cauchy problem of quasilinear wave equations with null condition in three space dimensions. The proof can display the following three features simultaneously: the Lorentz boost operator is not employed in the generalized energy estimates; the generalized energy of the solution will be always small, which was first observed by Alinhac; and the initial data are not assumed to have a compact support. Copyright © 2016 John Wiley & Sons, Ltd.     

Global existence of smooth solutions to 2D Chaplygin gases on curved space

This paper investigates the smooth solution of 2D Chaplygin gas equations on an asymptotically flat Riemannian manifold. Under the assumption that the initial data are close to a constant state and the vorticity of the initial velocity vanishes, we prove the global existence of smooth solutions to the Cauchy problem for two‐dimensional flow of Chaplygin gases on curved space. Copyright © 2016 John Wiley & Sons, Ltd.     

糖作为EPC合成手性源

近二十年来,有机合成化学有了很大的发展。对于一个复杂分子,化学家们不再满足于消旋体的合成,而是越来越致力于合成光学纯的目标分子。这就是通常所说的对映纯化合物的合成(Enantiomeric Purity Compound,简称EPC),它是当今有机合成注意的焦     

制革工业中的绿色化学与技术

论述了中国制革工业研究和实施绿色化学与技术的重要性。概述了国内外在绿色皮革化学品的开发和应用, 清洁的制革生产以及制革废弃物利用方面的研究成果, 并提出了今后的发展方向。     

癌症与病毒早期诊断的生物传感技术

本文对癌症与病毒早期诊断的生物传感技术进行了探讨, 展望了用于检测DNA、病毒、生物标志物的薄膜生物传感器的研究和应用前景。     

荧光探针技术在高分子科学中的应用

本文从原理及应用两个方面介绍了荧光探针技术在高分子科学中的应用, 讨论了荧光探针化合物的光化学和光物理行为, 以及如何用该技术来研究高分子的结构特征和高分子体系的动态过程问题, 包括利用该技术来研究高分子体系中的分子运动、能量转移和自由体积等重要例证。