利用静止轨道通信卫星向全球或某一地区无线电用户群体(如汽车音响)广播数字化的 CD 音乐、新闻和体育节目的业务,在国际上通称为数字音频广播(DAB,Digital Audio Broadcast),在美国通常叫作'卫星数字音频无线电业务'(SDARS,Sat...利用静止轨道通信卫星向全球或某一地区无线电用户群体(如汽车音响)广播数字化的 CD 音乐、新闻和体育节目的业务,在国际上通称为数字音频广播(DAB,Digital Audio Broadcast),在美国通常叫作'卫星数字音频无线电业务'(SDARS,Satellite DigitalAudio Radio Service)。这项卫星通信新业务是继卫星电视直播和卫星移动通信之后即将崛起的新兴产业。展开更多
Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform cal...Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform called cell-truss spar is studied using both computational fluid dynamics(CFD) and model test to investigate the VIM of the spar under different reduced velocities.The unique configuration of the cell-truss spar is carefully considered,and the unsteady flow around the spar is calculated and visualized in CFD simulations.A physical model with a scale ratio of 1:100 of the cell-truss spar is fabricated,and model tests are carried out in the current-generating ocean engineering basin.Many important parameters in VIM of the cell-truss spar are obtained,the occurrence of lock-in phenomenon is successfully simulated,and the mechanism and rules of lock-in are analyzed.展开更多
文摘利用静止轨道通信卫星向全球或某一地区无线电用户群体(如汽车音响)广播数字化的 CD 音乐、新闻和体育节目的业务,在国际上通称为数字音频广播(DAB,Digital Audio Broadcast),在美国通常叫作'卫星数字音频无线电业务'(SDARS,Satellite DigitalAudio Radio Service)。这项卫星通信新业务是继卫星电视直播和卫星移动通信之后即将崛起的新兴产业。
基金the National High Technology Research and Development Program (863) of China(No. 2006AA09A107)the Key Fundamental Research Project of Science and Technology Commission of Shanghai Municipality (No. 07XD14018)
文摘Spar platforms could be subject to vortex-induced-motions(VIM) in certain current conditions.Lockin is a phenomenon which occurs in a range of reduced velocities in VIM.In this paper,a new concept of spar platform called cell-truss spar is studied using both computational fluid dynamics(CFD) and model test to investigate the VIM of the spar under different reduced velocities.The unique configuration of the cell-truss spar is carefully considered,and the unsteady flow around the spar is calculated and visualized in CFD simulations.A physical model with a scale ratio of 1:100 of the cell-truss spar is fabricated,and model tests are carried out in the current-generating ocean engineering basin.Many important parameters in VIM of the cell-truss spar are obtained,the occurrence of lock-in phenomenon is successfully simulated,and the mechanism and rules of lock-in are analyzed.
