简介:对第48期“轮机维护与修理”海船船员考试试题进行分析,指出试题存在着内容重复以及与船员考试宗旨相背离等问题,并在此基础上提出相应的对策。
简介:在对45901与44901两期海船船员适任统考试题进行对比分析的基础上,从提高命题质量、航海英语教学和教材要和考纲契合、利用语料库对学生进行错误分析、研制应用于航海英语写作或翻译的自动评分系统及优化航海英语测试题型结构等方面提出对航海英语测试体系进行优化的建议。
简介:对新颁布的2011《中华人民共和国船员教育和培训质量管理规则》主要修订内容进行介绍,就其对航海院校和船员培训机构的影响进行分析,并提出适应新质量标准的质量管理体系改进对策。
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:基于船舶航行安全可靠的考虑,分析国内外船舶电力系统电能质量研究方法的现状,阐述电能质量研究方法,提出电能质量的评估与改善方法和技术手段.结合全电力推进船舶电力系统的特性,建立构建船舶电能质量监测评估系统,重点研究大型负载、船舶操纵及特殊工况时电网参数的影响,借助电能质量的评估与性能方法和技术手段,进行电能质量改善的仿真研究.