简介：Acomplianttowerismodeledasapartiallydry,partiallytapered,dampedTimoshenkobeamwiththesuperstructuremodeledasaneccentrictipmass,andanon-classicaldampedboundaryatthebase.Thefoundationismodeledasacombinationofalinearspringandatorsionalspring,alongwithparallellinearandtorsionaldampers(Kelvin-Voigtmodel).Thesuperstructureaddstothekineticenergyofthesystemwithoutaffectingthepotentialenergy,therebyreducingthenaturalfrequencies.Theweightofthesuperstructureactsasanaxialcompressiveloadonthebeam,reducingitsnaturalfrequenciesfurther.Theemptyspacefactorduetothetruss-typestructureofthetowerisincluded.Theeffectofsheardeformationandrotaryinertiaareincludedinthevibrationanalysis;withthenon-uniformbeammode-shapesbeingaweightedsumoftheuniformbeammode-shapessatisfyingtheendcondition.TheweightsareevaluatedbytheRayleigh-Ritz(RR)method,andverifiedusingfiniteelementmethod(FEM).Theweightofthesuperstructureactsasanaxialcompressiveloadonthebeam.Kelvin-Voigtmodelofstructuraldampingisincluded.Apartofthestructurebeingunderwater,thevirtualaddedinertiaisincludedtocalculatethewetnaturalfrequencies.Aparametricstudyisdoneforvariousmagnitudesoftipmassandvariouslevelsofsubmergence.ThecomputationalefficiencyandaccuracyoftheRayleigh-Ritzmethod,ascomparedtotheFEA,hasbeendemonstrated.Theadvantageofusingclosed-formtrialfunctionsisclearlyseenintheefficacyofcalculatingthevariousenergycomponentsintheRRmethod.

简介：WellsFargo证券公司:随着越来越多的LNG项目投入生产,LNG船队的利用情况也将得到改善,到2020年,利用率将从2017年的77%上升至95%。

简介：11月7日，由上海图书馆（上海科学技术情报研究所）、上海市科学技术情报学会主办，上海大学图书馆承办的“现代图书馆情报信息服务发展战略学术研讨会“在上海大学图书馆报告厅召开。研讨会以“图书馆。情报信息服务：转型、发展与创新”为主题，来自上海图书馆、同济大学图书馆、上海大学图书馆、复旦大学图书馆等单位的图书情报代表80余人参加研讨会，上海海事大学图书馆馆长（科技情报研究所所长）郑苏教授率业务代表一行7人参加了会议。