简介:Inordertoanalyzethespatialmaneuverabilityoftheremotelyoperatedunderwatervehicle(ROV),the6-DOFmotionmathematicmodeloftheROVwasfounded.HydrodynamicswereanalyzedbyusingtheTaylorseries.ThethrustersontheROVwerediscussed.Thispaperconsidersthreecasesofmotionsimulation:verticalmotion,rotationalmotionandZ-shapemotion.Aseriesofsimulationexperimentsshowedthatthe6-DOFmotionmathematicmodelwascorrectandreliable,andalsofitwiththescenesimulation.
简介:Thecriticaltechnicalproblemofunderwaterbottomobjectdetectionisfoundingastablefeaturespaceforechosignalsclassification.Thepastliteraturesmorefocusonthecharacteristicsofobjectechoesinfeaturespaceandreverberationisonlytreatedasinterference.Inthispaper,reverberationisconsideredasakindofsignalwithsteadycharacteristic,andtheclusteringofreverberationinfrequencydiscretewavelettransform(FDWT)featurespaceisstudied.Inordertoextracttheidentifyinginformationofechosignals,featurecompressionandclusteranalysisareadoptedinthispaper,andthecriterionofseparabilitybetweenobjectechoesandreverberationisgiven.TheexperimentaldataprocessingresultsshowthatreverberationhassteadypatterninFDWTfeaturespacewhichdiffersfromthatofobjectechoes.Itisproventhatthereisseparabilitybetweenreverberationandobjectechoes.
简介:按照和国际海事组织关于海员培训、发证和值班标准国际公约的要求,申请甲类、乙类航区三副以及上适任证书者应完成GMDSS通用操作员培训,并取得GMDSS通用操作员证书.
简介:有效的语言通信对船舶的安全航行和营运至关重要。根据IMO事故报告分析,通信不利是导致事故发生的重要因素之一。而缺乏使用SMCP的意识是通信不利的主要原因。文章主要介绍SMCP的结构和通信特征以及如何将SMCP应用到VHF通信的教学实践中去。
简介:Ananalyticalstudywaspresentedonactivecontrolofsoundtransmissionintoavibro-acousticenclosurecomprisingtwoflexibleplates.Twotypesofactuatorswereused,i.e.acousticactuatoranddistributedleadzirconatetitanatepiezoelectric(PZT)actuatorinsteadofpointforceactuator.Usingthemodalacoustictransferimpedance-mobilitymatrices,theexcitationandinteractioninthecoupledsoundtransmissionsystemcanbedescribedwithclearphysicalsignificance.Withthecontrolsystemdesignedtogloballyreducethesoundfield,differentcontrolsystemconfigurationswereconsidered,includingthestructuralactuatorontheincidentplate,actuatoronthereceivingplate,acousticactuatoronthecavity,andtheircombinations.Theeffectivenessandperformanceofthecontrolstrategycorrespondingtoeachsystemconfigurationwerecomparedanddiscussed.Theroleandcontrolmechanismofeachtypeofactuatorwereofparticularinterest.Itwasshownthattheincidentplateactuatoriseffectiveincontrollingthecavity-dominatedmodesandthestructuralmodesdominatedbytheincidentplateandreceivingplate.Twomaincontrolmechanismsareinvolvedinthiscontrolconfiguration,i.e.,modalsuppressingandmodalrearrangement.Forcontrolsystemconfigurationwithonlyacousticactuatorintheenclosure,themechanisminvolvedinthisarrangementispurelymodalsuppression.Desirableplacementsofstructuralactuatorsintermsoftotalpotentialenergyreductionwerealsodiscussed.
简介:以集装箱班轮航线为基础,构建以港口为节点、港口间的运力为边权重的有向加权海运网络,并从中抽取出与广州港、深圳港以及香港港有联系的港口节点和边.在此基础上,分别从出口货流和进口货流两个角度对广州港、深圳港以及香港港的集装箱货流在全球17个海运区域的空间分布情况进行对比,并就出口货流和进口货流在上述三个港口之间的集聚程度进行了分析.结果表明:(1)无论是在进口货流还是出口货流方面,与香港港建立联系的海运区域数量都是最多的,香港港的港口通达性最好;(2)深圳港的货流总量高于香港港和广州港;(3)进口货流主要集中在香港港,出口货流主要集中在深圳港;(4)东非、南部非洲、南美东岸和西非区域的进口货流呈现高度集聚分布的特点.