铅球飞行距离与其影响因素的力学分析

通过对滑步掷球时铅球飞行距离及其影响力学因素的相互关系的分析,详细讨论了决定飞行距离的独立力学变量对飞行距离的影响,同时指出了最佳用力角的物理意义及一些对实际有益的重要结论.

Interaction of a circular cavity and a beeline crack in right-angle plane impacted by SH-wave

The problem of scattering of SH-wave by a circular cavity and an arbitrary beeline crack in right-angle plane was investigated using the methods of Green's function,complex variables and muti-polar coordinates.Firstly,we constructed a suitable Green's function,which is an essential solution to the displacement field for the elastic right-angle plane possessing a circular cavity while bearing out-of-plane harmonic line source load at arbitrary point.Secondly,based on the method of crack-division,integration for solution was established,then expressions of displacement and stress were obtained while crack and circular cavities were both in existence.Finally,the dynamic stress concentration factor around the circular cavity and the dynamic stress intensity factor at crack tip were discussed to the cases of different parameters in numerical examples.Calculation results show that the crack produces adverse engineering influence on both of the dynamic stress concentration factor and the dynamic stress intensity factor.

出手速度之间的推铅球出手角度与关系

根据对实测数据的分析,在合理的假设之下,从数学与力学角度出发,对投掷铅球的出手角度与出手速度之间的关系进行了探讨,通过对出手角与用力角的分析讨论,给出了投掷铅球的最佳出手角度的计算方法。

“台钓”:竞技与休闲

二、钓组及组配原则 我们在接触“台钓”之初,得到的它的钓组的搭配信息都是小漂、小坠、细线、小钩。在具体的组配上,通常是(自风线至钩)太空豆(两枚)—插漂座—太空豆(两枚)—太空豆(一枚)—铅皮座—太空豆(一枚)—转环—带钩的长脑线。 这是最常用的“台钓”钓组组配方法,现在市售的太空豆,每个包装袋里也是六枚,按照这个配组供应的。这六个太空豆,从风线至钩的顺序来说,第二、三枚纯粹是为了固定插漂座,五、六枚是为了固定铅皮座,而一、四枚除了具有协助固定插漂座的功能外,更主要的作用是一但钓点移动或钓位转移。