Free transverse vibration analysis of an underwater launcher based on fluid-structure interaction

A pneumatic launcher is theoretically investigated to study its natural transverse vibration in water. Considering the mass effect of the sealing cover, the launcher is simplified as a uniform cantilever beam with a top point mass. By introducing the boundary and continuity conditions into the motion equation, the natural frequency equation and the mode shape function are derived. An iterative calculation method for added mass is also presented using the velocity potential function to account for the mass effect of the fluid on the launcher. The first 2 order natural frequencies and mode shapes are discussed in external flow fields and both external and internal flow fields. The results show good agreement with both natural frequencies and mode shapes between the theoretical analysis and the FEM studies. Also, the added mass is found to decrease with the increase of the mode shape orders of the launcher. And because of the larger added mass in both the external and internal flow fields than that in only the external flow field, the corresponding natural frequencies of the former are relatively smaller.     

浅谈小车免费放行期间高速公路日常养护应采取的对策与措施

高速公路每天的日常养护必不可少,即使是小车免费放行期间。本文主要就小车免费放行的相关政策、节日期间高速公路日常养护带来的压力进行阐述,并就如何从容应对高速公路免费通行期间的超大规模车流、如何扎实、安全搞好日常养护工作提出了一系列对策措施。     

重庆市渝北政府免费送“金刚”——全国首批由政府买单的恒通“金刚校车”投入运营

11月22日,重庆市渝北区校车公司成立仪式在渝北区区政府广场隆重举行。渝北区区委书记周甸、区长黄玉林及相关部门负责人,恒通客车总经理唐乾栋、渝北城区中小学校长、部分教师代表及金港国际实验小学师生等400余人出席了仪式。据了解,此次赠送的校车是由渝北区区政府出资采购的10台被誉为“金刚校车”的恒通专用校车,是全国首批由政府买单、免费赠送使用的校车。     

回家的路在网上——小编亲历春运之实名制购票

据铁路部门发布的消息称,2012年1月1日起,旅客购买火车票均须凭本人有效身份证件购票,并持车票及购票时所使用的乘车人本人有效身份证件原件(免费乘车的儿童及持儿童票     

回家的路在网上——小编亲历春运之实名制购票

据铁路部门发布的消息称,2012年1月1日起,旅客购买火车票均须凭本人有效身份证件购票,并持车票及购票时所使用的乘车人本人有效身份证件原件（免费乘车的儿童及持儿童票乘车的儿童除外）进站、乘车,全国所有旅客列车实行车票实名制。