简介：Themethodofcoupledmodeisintroducedforinvestigationofbi-staticdistantbottomreverberationofimpulsivesourceinshallowwater,whichwillnotcontradictwithprincipleofreciprocityinallcases.Andthemethodofmulti-polefordirectionalsourceisalsointroduced.Itshowsthatincaseoflayeredmedium,intensityofbi-staticbottomreverberationwilldeceaseaccordingtothecubicpowerofreceivingtimet,andthetransversespatialcorrelationofbottomreverberationisalittlegreaterthanlongitudinalcorrelationforequalseparationofreceivers,andbothvaryinformwiththereceivingtime.

简介：Inordertogetsomeusefulparametersforgridgenerationofcatamaran,theCFDsoftwareFLUENTisusedtoinvestigatethemaineffectsofgridgenerationonflowfieldcalculation.Theinfluencesofsomeelementsareinvestigatedwithaseriesofcalculationsinthepresentpaper,andsomealterativesareproposed.Theproposedalterativesbasedontheanalysisoftheeffectsareusedforacatamaranresistancecalculation,comparisonsofthecalculatedresultswithexperimentaldatashowgoodagreement.Itshowsthattheresearchresultofthispaperisusefulforthenumericalcalculationofcatamaran.

简介：Inordertoanalyzethespatialmaneuverabilityoftheremotelyoperatedunderwatervehicle(ROV),the6-DOFmotionmathematicmodeloftheROVwasfounded.HydrodynamicswereanalyzedbyusingtheTaylorseries.ThethrustersontheROVwerediscussed.Thispaperconsidersthreecasesofmotionsimulation:verticalmotion,rotationalmotionandZ-shapemotion.Aseriesofsimulationexperimentsshowedthatthe6-DOFmotionmathematicmodelwascorrectandreliable,andalsofitwiththescenesimulation.

简介：BasedonthetraditionalSmoothedParticleHydrodynamics(SPH)algorithm,thelinked-listsearchalgorithmcombinedwiththevariablesmoothinglengthandsquaresupportdomainwasputforwardtoimprovethecalculationefficiencyandguaranteethecalculationaccuracy.Thephysicalprocessofhighvelocityfragmentimpactonabroadsideliquidcabinwasprogrammedforsimulation.ThenumericalresultsagreedwellwiththoseofthegeneralsoftwareANSYSAUTODYN,whichverifiestheeffectivenessandfeasibilityofthenumericalmethod.Fromtheperspectiveoftheouterplatethicknessoftheliquidcabin,thewidthoftheliquidcabin,andincidentangleofthefragment,theinfluenceoftheseparametersonprotectivemechanismswasanalyzedtoprovideabasisforprotectivedesignofabroadsideliquidcabin.Resultsshowthattheinfluenceofouterplatethicknessisnotobvious;therefore,theconventionaldesigncanbeadoptedinthedesignoftheouterplate.Thewidthoftheliquidcabinhasagreatinfluenceontheresidualvelocityofthefragmentandthewidthoftheliquidcabinshouldbedesignedtobeaswideaspossibleunderthepremiseofmeetingotherrequirements.Thereisacertainincidentangleinwhichthevelocityattenuationofthefragmentismostobvious,andthehigh-pressurezoneneartheinnerplateisasymmetric.Theinnerplateofliquidcabinshouldbestrengthenedaccordingtothehullform,principaldimensions,andvulnerablepoints.

简介：Tosolvethedimensionallimitationsofphysicalmodelsintests,anequivalentwaterdepthtruncateddesignforaclassicalSPARworkingin913mwaterwasinvestigated.Thewaterdepthwasreducedto736mandthento552m.Asthiswasdone,themooringlinelengths,EAvalue,andmasspermeterwereadjusted.Truncationrulesandformulasforparametersandtruncationfactorswereproposed.SPARstaticcharacteristicsweremadetobeconsistentwiththoseatfullwaterdepth.Thenfurthertime-domaincoupledanalysiswascarriedoutfortheSPARwhenthemooringsystemexperiencedwaves.Themooringlinesweresimulatedbyquasi-staticmethod.Globalresponsesandmooringlineforceswerefoundtoagreewellwithtestresultsforaprototypeatthatwaterdepth.Thetruncationmethodprovedtoberobustandreliable.

简介：文章基于作者在中外合作建筑工程专业多年的教学实践，着重探讨了教师使用该教材进行双语教学的模式和学生学习英文课程的方法，进而提出使用英文课程提高教学效果相应的建议与对策。

简介：Thispaperpresentsananalyticalstudyontheinfluenceofedgerestrainingstiffnessonthetransversevibrationsofrectangularplatestructure.AnimprovedFourierseriesmethodwasemployedtoanalyzethetransversevibrationofplatestructurewithgeneralelasticallyrestrainedboundaryconditions.AlinearcombinationofadoubleFourierseriesandeightauxiliarytermswassoughtastheadmissiblefunctionoftheflexuraldisplacementoftheplate,eachtermbeingacombinationofapolynomialfunctionandasinglecosineseriesexpansion.Theauxiliarytermswereintroducedtoensureandimprovethesmoothnessoftheoriginaldisplacementfunctionanditsderivativesattheboundaries.Severalnumericalexamplesweregiventodemonstratethevalidityandaccuracyofthecurrentsolution.Theinfluencesoftranslationalandrotationalstiffnessonthenaturalfrequenciesandmodeshapesofplatewereanalyzedbynumericalresults.Theresultsshowthatthetranslationalstiffnesshasbiggerinfluenceonthenaturalfrequenciesthantherotationalstiffness.Itisgenerallywellknownthatlittlechangeoftherotationalstiffnesshaslittleinfluenceonthemodeshapesofplate.However,thecurrentworkshowsthataverylittlechangeofrotationalstiffnessvaluemayleadtoalargechangeofthemodeshapesofasquareplatestructure.

简介：Thispaperfocusesontheresearchofasemi-submersibleplatformequippedwithaDP-assistedmooringsystem.BasedontheworkingprinciplesoftheDP-assistedmooringsystemandthemodeloftheplatformmotion,atimedomainsimulationprogramisappliedtoanalyzetheimpact,inthecaseofonelinefailure,ontheplatformmotion,powerconsumptionofthethrustersandthetensionofthemooringlines.Theresultsshowthat,underthe10-yearwinddominant,aonelinefailurewillhavelittleimpactonthetensionofthemooringlines.Whenthefailurelineiswindward,thepowerconsumptionwillincreasegreatlywithaweakenedpositionofaccuracy.Howeverwhenthefailurelineisleeward,thepowerconsumptionwillbereducedwithapartlystrengthenedpositionofaccuracy.

简介：Fishareabletomakegooduseofvortices.Inacomplexflowfield,manyfishcontinuetomaintainbothefficientcruisingandmaneuverability.Traditionalman-madepropulsionsystemsperformpoorlyincomplexflowfields.Withfish-likepropulsionsystems,itisimportanttopaymoreattentiontocomplexflowfields.Inthispaper,theinfluenceofvorticesonthehydrodynamicperformanceof2-Dflapping-foilswasinvestigated.Theflapping-foilheavedandpitchedundertheinfluenceofinflowvorticesgeneratedbyanoscillatingD-sectioncylinder.Anumericalsimulationwasrunbasedthefinitevolumemethod,usingthecomputationalfluiddynamics(CFD)softwareFLUENTwithReynolds-averagedNavier-Stokes(RANS)equationsapplied.Inaddition,dynamicmeshtechnologyandpostprocessingsystemswerealsofullyused.Thecalculationsshowedfourmodesofinteraction.Thehydrodynamicperformanceofflapping-foilswasanalyzedandtheresultscomparedwithexperimentaldata.Thisvalidatedthenumericalsimulation,confirmingthatflapping-foilscanincreaseefficiencybyabsorbingenergyfrominflowvortices.

简介：Windpowerhasmaderapidprogressandshouldgainsignificanceasanenergyresource,givengrowinginterestinrenewableenergyandcleanenergy.Offshorewindenergyresourceshaveattractedsignificantattention,as,comparedwithland-basedwindenergyresources,offshorewindenergyresourcesaremorepromisingcandidatesfordevelopment.Seawindsaregenerallystrongerandmorereliableandwithimprovementsintechnology,theseahasbecomeahotspotfornewdesignsandinstallationmethodsforwindturbines.Inthepresentpaper,basedonexperiencebuildingoffshorewindfarms,recommendedfoundationstyleshavebeenexamined.Furthermore,waveeffectshavebeeninvestigated.Thesplitinstallationandoverallinstallationhavebeenillustrated.Methodsappropriatewheninstallingasmallnumberofturbinesaswellasthoseusefulwheninstallinglargenumbersofturbineswereanalyzed.Thisinvestigationofinstallationmethodsforwindturbinesshouldprovidepracticaltechnicalguidancefortheirinstallation.

简介：Thecriticaltechnicalproblemofunderwaterbottomobjectdetectionisfoundingastablefeaturespaceforechosignalsclassification.Thepastliteraturesmorefocusonthecharacteristicsofobjectechoesinfeaturespaceandreverberationisonlytreatedasinterference.Inthispaper,reverberationisconsideredasakindofsignalwithsteadycharacteristic,andtheclusteringofreverberationinfrequencydiscretewavelettransform(FDWT)featurespaceisstudied.Inordertoextracttheidentifyinginformationofechosignals,featurecompressionandclusteranalysisareadoptedinthispaper,andthecriterionofseparabilitybetweenobjectechoesandreverberationisgiven.TheexperimentaldataprocessingresultsshowthatreverberationhassteadypatterninFDWTfeaturespacewhichdiffersfromthatofobjectechoes.Itisproventhatthereisseparabilitybetweenreverberationandobjectechoes.

简介：Foralargefloatingvesselinwaves,radiationdampingisnotanaccuratepredictionofthedegreeofrollunlikeotherdegreesoffreedommotion.Therefore,togettheknowledgeofrollmotionperformanceofdeepwaterpipelaycranevesselsandtokeepthevesselworkingsafety,thepaperpresentstherelationshipbetweenaseriesofdimensionlessrolldampingcoefficientsandtherollresponseamplitudeoperator(RAO).Byusingtwokindsofempiricaldata,therolldampingisestimatedinthecalculationflow.Aftergettingtherolldampingcoefficientfromthemodeltest,apredictionofrollmotioninregularwavesisevaluated.Accordingtothewaveconditionintheworkingregion,shorttermstatisticsofrollmotionarepresentedunderdifferentwaveparameters.Moreover,therelationshipbetweenthemaximalrollresponseleveltopeakspectralwaveperiodandtherolldampingcoefficientisinvestigated.Resultsmayprovidesomereferencetodesignandimprovethiskindofvessel.

简介：Inunderwatertargetdetection,thebottomreverberationhassomeofthesamepropertiesasthetargetecho,whichhasagreatimpactontheperformance.Itisessentialtostudythedifferencebetweentargetechoandreverberation.Inthispaperbasedontheuniqueadvantageofhumanlisteningabilityonobjectsdistinction,theGammatonefilteristakenastheauditorymodel.Inaddition,time-frequencyperceptionfeaturesandauditoryspectrafeaturesareextractedforactivesonartargetechoandbottomreverberationseparation.Thefeaturesoftheexperimentaldatahavegoodconcentrationcharacteristicsinthesameclassandhavealargeamountofdifferencesbetweendifferentclasses,whichshowsthatthismethodcaneffectivelydistinguishbetweenthetargetechoandreverberation.

简介：路径规划是自主式水下潜器(AUV)导航研究的重要课题,AUV可用于未知环境如海洋空间探测.在大范围海洋环境中,应用蚁群优化原理对自主式水下潜器的全局路径规划问题进行了研究.引入栅格建模方法建立了蚁群可视图模型,设计了蚁群信息素更新规则;给出了蚁群全局路径规划的操作步骤;针对蚁群规划路径不平滑问题,设计了切割算子和插点算子.仿真实验结果表明,蚁群全局规划算法非常适合于求解复杂环境中的规划问题,规划时间短、路径平滑,其原型系统可应用于非结构化无人环境监测。

简介：Basedontheprincipleofimpedancemismatching,theperformanceofrigidvibrationisolationmassinimpedingvibrationwavepropagationwasdiscussedfromtheperspectiveofwaveapproach.BasedonFEM,theinfluenceofitsweightaswellasthecross-sectionshapeparametersontheisolationperformanceofrigidvibrationisolationmasswasstudiedthroughnumericalsimulation.Theresultsshowthatrigidvibrationisolationmasscaneffectivelyimpedethepropagationofthemediumandhighfrequencyvibrationwaves,andtheheavierthevibrationisolationmass,thebettertheisolationperformance.Forlowfrequencywaves,thevibrationisolationeffectisnotsoobvious;forarectangularvibrationisolationmass,theisolationperformancecouldbeeffectivelyimprovedbyincreasingthecross-sectionheightandreducingthecross-sectionwidth.Ausefulreferencewasprovidedfortheapplicationofrigidvibrationisolationmassestothevibrationisolationandnoisereductionofshipstructure.

简介：AmethodofreliabilityanalysisbasedonadirectstrengthcalculationemployingthevonMisesstressfailurecriterionispresentedhere.Theshorttermstraindistributionsofshiphullstructuralcomponentsareidentifiedthroughthestatisticalanalysisofthewave-inducedstrainhistoryandthelongtermdistributionsbytheweightedsummationoftheshorttermstraindistributions.Thewave-inducedlongtermstraindistributioniscombinedwiththestillwaterstrain.Theextremestraindistributionoftheresponsestrainisobtainedbystatisticalanalysisofthecombinedstrains.ThelimitstatefunctionofthereliabilityanalysisisbasedonthevonMisesstressfailurecriterion,includingtherelateduncertaintiesduetothequalityofthematerialandmodeluncertainty.ThereliabilityindexiscalculatedusingFORMandsensitivityanalysisofeachvariablethathaseffectsonthereliabilityisalsodiscussed.

简介：水动力学与固体力学交叉的流固耦合理论是船舶与海洋工程结构响应分析与直接设计的重要工具.本文应用卷变积方法,按照广义力和广义位移之间的对应关系,将弹性动力学的基本方程卷乘上相应的虚量,然后积分,代数相加,并考虑到体积力和面积力均为伴生力,建立了非保守系统初值问题的两类变量的广义拟余能原理.应用广义拟余能原理研究流固耦合问题,分析了结构的动力响应,给出同时求解力类量和位移类量两类变量的计算方法。

简介：Theplowofthesubmarineplowingtrencherisoneofthemainfunctionalmechanisms,anditsoptimizationisveryimportant.Thedesignparametersplayaverysignificantroleindeterminingtherequirementsofthetowingforceofavessel.Amulti-objectivegeneticalgorithmbasedonanalyticalmodelsoftheplowsurfacehasbeenexaminedandappliedineffortstoobtainoptimaldesignoftheplow.Foraspecificsoilcondition,thedraftforceandmoldboardsurfaceareawhicharethekeyparametersintheworkingprocessoftheplowareoptimizedbyfindingthecorrespondingoptimalvaluesoftheplowbladepenetrationangleandtwosurfaceanglesofthemaincuttingbladeoftheplow.Parameterssuchasthemoldboardsideangleofdeviation,moldboardliftangle,angularvariationofthetangentline,andthespanninglengtharealsoanalyzedwithrespecttotheforceofthemoldboardsurfacealongsoilflowdirection.Resultsshowthattheoptimizedplowhasanimprovedplowperformance.Thedraftforcesofthemaincuttingbladeandthemoldboardare10.6%and7%,respectively,lessthantheoriginaldesign.ThestandarddeviationofGaussiancurvatureofmoldboardisloweredby64.5%,whichimpliesthatthesmoothnessoftheoptimizedmoldboardsurfaceismuchgreaterthantheoriginal.

简介：Reconfigurabilityoftheelectricalnetworkinashipboardpowersystem(SPS)afteritsfailureiscentraltotherestorationofpowersupplyandimprovessurvivabilityofanSPS.Thenavigationalprocesscreatesasequenceofdifferentoperatingconditions.Thepriorityofsomeloadsdiffersinchangingoperatingconditions.AfteranalyzingcharacteristicsoftypicalSPS,amodelwasdevelopedusedagradeⅢswitchboardandanenvironmentalprioritizingagent(EPA)algorithm.Thisalgorithmwaschosenasitislogicallyandphysicallydecentralizedaswellasmulti-agentoriented.TheEPAalgorithmwasusedtodecideonthedynamicloadpriority,thenitselectedthemeanstobestmeetthemaximumpowersupplyload.Thesimulationresultsshowedthathigherpriorityloadswerethefirsttoberestored.Thesystemsatisfiedallnecessaryconstraints,demonstratingtheeffectivenessandvalidityoftheproposedmethod.

简介：Themostcriticalissueinthesteelcatenaryriserdesignistoevaluatethefatiguedamageinthetouchdownzoneaccurately.Appropriatemodelingoftheriser-soilresistanceinthetouchdownzonecanleadtosignificantcostreductionbyoptimizingdesign.Thispaperpresentsaplasticitymodelthatcanbeappliedtonumericallysimulateriser-soilinteractionandevaluatedynamicresponsesandthefatiguedamageofasteelcatenaryriserinthetouchdownzone.Utilizingthemodel,numerousriser-soilelementsareattachedtothesteelcatenaryriserfiniteelements,inwhicheachsimulateslocalfoundationrestraintalongtherisertouchdownzone.Theriser-soilinteractionplasticitymodelaccountsforthebehaviorwithinanallowablecombinedloadingsurface.Themodelwillberepresentedinthispaper,allowingsimplenumericalimplementation.Moreimportantly,itcanbeincorporatedwithinthestructuralanalysisofasteelcatenaryriserwiththefiniteelementmethod.Theapplicabilityofthemodelisinterpretedtheoreticallyandtheresultsareshownthroughapplicationtoanoffshore8.625″steelcatenaryriserexample.Thefatigueanalysisresultsofthelinerelasticriser-soilmodelarealsoshown.Accordingtothecomparisonresultsofthetwomodels,thefatiguelifeanalysisresultsoftheplasticityframeworkarereasonableandthehorizontaleffectsoftheriser-soilinteractioncanbeincluded.