A transport-rate model of wind-blown sand

Sand transport by wind plays an important role in environmental problems.Formulating the sand-transport rate model has been of continuing significance,because the majority of the existing models relate sand-transport rate to the wind-shear velocity.However,the wind-shear velocity readapted to blown sand is difficult to determine from the measured wind profiles when sand movement occurs,especially at high wind velocity.Detailed wind tunnel tests were carried out to reformulate the sand-transport rate model,followed by attempts to relate sand-transport rate to parameters of wind velocity,threshold shear-velocity,and grain size.Finally,we validated the model based on the data from field observations.

超共轭效应对有机化合物结构和反应性的影响

超共轭效应是基础有机化学教学中的一个重要知识点,是基团诱导效应和共轭效应的补充和发展。本文通过基础有机化学教学中的常见实例,分析和阐述了多种超共轭效应对有机化合物及中间体结构稳定性和相对反应性的贡献。

有机化学课程公共答疑平台的建设实践与效果分析

有机化学是许多理工农医专业的基础课,其知识点丰富且有一定难度,这些因素使得课后答疑的需求量大且时效性较强。在互联网环境发达茁壮的今天,利用互联网构建教学答疑平台对线下答疑进行补充可以成为辅助教学的一种重要手段。浙江大学化学系学业指导中心有机化学答疑组在摸索尝试后成功建设了一种有机化学教学辅助公共答疑平台,正式运营一年中,得到了来自各个院系学生的积极参与及化学系师生的鼎力支持,评价良好。本文将介绍利用学生志愿者组织及QQ群建设实现公共答疑平台的方法、效果与改进方向。