简介:集运业可能会发生变化,但驱动因素将是技术革命而不是行业整合;迄今为止出现的相关证据是,行业整合减少了班轮公司数量,但没有改变他们的运营行为。例如,没有迹象表明市场竞争减弱。在短暂停顿后,各大班轮公司已经重新开始超大货轮订购。麦肯锡公司(McKinsey)在最近发布(但又很快撤回)的一份白皮书中颇有争议地指出,运力过剩“将会长期存在”。区块链——下一个伟大发明?但是,可能具有历史意义的好运正在降临!在航运业进行整合的同时,出现了有人认为将会改变世界的下一个突破性技术:分布式账本,即区块链。尽管这种技术有待发展,而且可能需要多年时间才能实现,但人类首次有望找出一条大幅降低全球贸易相关成本的途径。
简介:Thispaperfocusesontheresearchofasemi-submersibleplatformequippedwithaDP-assistedmooringsystem.BasedontheworkingprinciplesoftheDP-assistedmooringsystemandthemodeloftheplatformmotion,atimedomainsimulationprogramisappliedtoanalyzetheimpact,inthecaseofonelinefailure,ontheplatformmotion,powerconsumptionofthethrustersandthetensionofthemooringlines.Theresultsshowthat,underthe10-yearwinddominant,aonelinefailurewillhavelittleimpactonthetensionofthemooringlines.Whenthefailurelineiswindward,thepowerconsumptionwillincreasegreatlywithaweakenedpositionofaccuracy.Howeverwhenthefailurelineisleeward,thepowerconsumptionwillbereducedwithapartlystrengthenedpositionofaccuracy.
简介:Fishareabletomakegooduseofvortices.Inacomplexflowfield,manyfishcontinuetomaintainbothefficientcruisingandmaneuverability.Traditionalman-madepropulsionsystemsperformpoorlyincomplexflowfields.Withfish-likepropulsionsystems,itisimportanttopaymoreattentiontocomplexflowfields.Inthispaper,theinfluenceofvorticesonthehydrodynamicperformanceof2-Dflapping-foilswasinvestigated.Theflapping-foilheavedandpitchedundertheinfluenceofinflowvorticesgeneratedbyanoscillatingD-sectioncylinder.Anumericalsimulationwasrunbasedthefinitevolumemethod,usingthecomputationalfluiddynamics(CFD)softwareFLUENTwithReynolds-averagedNavier-Stokes(RANS)equationsapplied.Inaddition,dynamicmeshtechnologyandpostprocessingsystemswerealsofullyused.Thecalculationsshowedfourmodesofinteraction.Thehydrodynamicperformanceofflapping-foilswasanalyzedandtheresultscomparedwithexperimentaldata.Thisvalidatedthenumericalsimulation,confirmingthatflapping-foilscanincreaseefficiencybyabsorbingenergyfrominflowvortices.