简介：我国已正式成为世界贸易组织成员,这意味着国门进一步开放,中国社会各个领域将发生一系列变化,教育市场也必然向WTO其他成员国开放.大连海事大学作为全国唯一一所由交通部直接管理的培养航运事业高级人才的国家重点院校,发展的机遇和面临的挑战同时存在.能否培养出大批顺应世界潮流、在国际市场中具有竞争能力的高级航海人才,关系着国家的利益,也维系我校航海类专业的发展前途.

简介：四川全省共有河流1419条，流程共44000多公里，通航河流176条，通航水库、湖泊147个；航道里程11725公里，居全国第四、西部首位，其中七级以上航道4026公里（三、四级航道990公里）；港口17个，1000吨级泊位50个。

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.