Solid−solid phase transition of tungsten induced by high pressure:A molecular dynamics simulation

The phase transition of tungsten(W)under high pressures was investigated with molecular dynamics simulation.The structure was characterized in terms of the pair distribution function and the largest standard cluster analysis(LSCA).It is found that under 40−100 GPa at a cooling rate of 0.1 K/ps a pure W melt first crystallizes into the body-centred cubic(BCC)crystal,and then transfers into the hexagonal close-packed(HCP)crystal through a series of BCC−HCP coexisting states.The dynamic factors may induce intermediate stages during the liquid−solid transition and the criss-cross grain boundaries cause lots of indistinguishable intermediate states,making the first-order BCC−HCP transition appear to be continuous.Furthermore,LSCA is shown to be a parameter-free method that can effectively analyze both ordered and disordered structures.Therefore,LSCA can detect more details about the evolution of the structure in such structure transition processes with rich intermediate structures.

Tracker视频分析软件在高中物理教学中的应用——以自由落体运动为例

Tracker作为一款具有动态捕捉和数学建模双重功能的视频分析软件,为丰富教学方式、培养学生核心素养提供了新思路。基于传统实验教学中常见的问题,以高中物理必修“自由落体运动”为例,设计了符合学生认知特点的教学过程,运用Tracker视频分析软件采集和分析实验数据,提高了教学效率,激发了学生兴趣,提升了学生的核心素养。