衍射法测量金属丝的杨氏模量

本文提出了一种新的测量金属丝杨氏模量的方法--夫琅禾费单缝衍射法.平行光遇到由金属丝被拉伸形变而形成的单缝,产生衍射,用CCD光强分布测量仪接收衍射光信号,用示波器定标方法测量衍射角,可以精确计算金属丝的杨氏模量.最后与普通光杠杆放大法比较,对可能引入的误差来源做了分析,结果证明,本方法测量精度更高、相对误差更小.     

Statefinder Diagnostic for Born--Infeld Type Dark Energy Model

Using a new method cafled the statefinder diagnostics which can make one dark energy model differ from the others, we investigate the dynamics of Born-Infeld （B-I） type dark energy model. The evolution trajectory of B-I type dark energy with Mexican hat potential model with respect to e-folding time N is shown in the r（s） diagram. When the parameter of noncanonical kinetic energy term η→0 or kinetic energy φ^2 →0, the B-I type dark energy （K-essence） model reduces to the quintessence model or the ACDM model corresponding to the statefinder pair （r, s） = {1, 0} respectively. As a result, the evolution trajectory of our model in the r（s） diagram in Mexican hat potential is quite different from those of other dark energy models. The current values of parameters Ωφ and wφ in this model meet the latest observations WMAP5 well.