研究了湿热/干燥环境交替作用下碳纤维复合材料的吸湿/脱湿特性.完成了复合材料层合板的六次高温高湿/干燥环境交替作用试验.通过观察复合材料基体和界面微观形貌,分析环境损伤的特征和演化规律.研究结果表明:在湿热/干燥环境交替作用下,复合材料的吸湿扩散速率逐渐变大,平衡吸湿量有所增加,脱湿时间明显增大.这表明材料特性和微观结构发生了一些变化;使用多项式拟合吸湿/脱湿试验数据精度较好,并依据Fick定律推导出多次吸湿-脱湿方程;观察第四、六次吸湿后复合材料的界面微观形貌差异不大,界面破坏基本达到"饱和";最后提出"总损伤"和"残留损伤"来描述湿热/干燥交替作用而产生的环境损伤,为损伤表征和性能预测提供新思路.

课内实验是大学化学教学中的重要一环.但当前,由于学时少、知识点多及学生差异性大,使得大学化学实验教学难以有效开展.为了解决这一问题,基于互联网和各种信息技术的发展,提出在大学化学实验教学中开展线上线下混合式教学.通过实验教学内容的优化、线上教学平台的建立,实现了课前线上预习、课中线下互动及课后线上线下讨论的教学过程.学生的空闲时间得到了有效利用,最终,显著提高了教学效果.

Heuristic teaching is an important measure to improve teaching quality,so it is attracting more and more attention.This paper interprets it from such aspects as the core features of heuristic teaching,how to implement heuristic teaching and several issues that should be noticed in heuristic teaching,hoping to help teachers use heuristic teaching more effectively in teaching practice.

The main contribution of this paper lies in the design of a dynamic intermittent feedback control strategy and the determination of higher period by combining Poincare map and power spectrum technique. The controlling methods can save great energy and transmit the chaos in a vibro-impact system into different nP higher periodic and nH quasiperiodic orbits. A desired unstable periodic orbit, which is embedded in the chaotic attractor, is stabilized and the controlled system can maintain its stable dynamical behaviors in large windows of parameter space. The number of higher periodic orbits and quasi-periodic orbits represented by attracting invariant circles can be identified accurately. Some typical control results are given by numerical analysis, which are helpful for designing, vibration control and safety operating of vibro-impact systems.