A new coefficient of Prandtl's relation was obtained from the experimental data. Compared with three conventional relations of friction factor, the range of Reynolds number was extended.

Based on the relation between reliability and lifetimes of rolling bearings, this paper gave a lifetime calculation method which depends on the relevant reliability range.

By employing the semiclassical theory of lasers, a relation between the frequency tuning range and various laser parameters is given in this article.