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:针对钻井平台波浪补偿控制系统,运用意大利ATOS公司的高性能三位四通电液比例换向阀和天车主动油缸来构造钻柱升沉补偿装置的传递函数,提出一种参数自适应模糊PID集成控制策略.MATLAB/Simulink仿真结果表明,该控制系统性能稳定,可以补偿平台94.3%的升沉运动,补偿精度较高,为搭建3000m深海钻井平台波浪补偿装置可行性提供了可靠的理论依据.
简介:船舶自动识别系统已广泛应用于船舶航运,但在水利滩涂圈围工程中引进与应用该系统尚属首次。上海横沙东滩圈围(七期)工程引进了船舶自动识别系统(AIS),作为安全管理技术人员,须全面掌握和熟练运用各项技术及管理措施。根据中国海事局的相关规范标准,该工程监理从过程管理的角度,制定了施工事前、事中、事后控制的监理流程及措施,较大提升了船舶航行安全的管控水平和船舶航行安全控制的技术水平。