资源描述:
《海浪和舰艇尾迹产生的弱磁信号分析》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、ABSTRACTABSTRACTTheseawaterisaweakconductivemedium.Whentheseawatermovesthroughthegeomagneticfield,itcouldgeneratetime-changingelectriccurrentsinthemedium.Theelectriccurrentswouldproducemeasurableelectromagneticfieldsinthewholespace.Thisthesisisconcer
2、nedwithsimulationsandanalysestotheweakmagneticfieldsinducedbythreedifferentmotionsofseawaterthatcutthegeomagneticfield:theseawavesdrivenbywinds,thewakesduetomovingshipandmovingsubmarine.Theexaminationstotheinducedmagneticfieldswilldeepenourknowledgea
3、bouttheoceanicmagneticenvironment.Itisalsohelpfulinprovidingareliabletheoreticalfoundationforaeromagneticanomalydetectionofunderwatermovingtargetandelectromagneticexplorationofseabedresources.Inordertoperformanalysistothesolutionoftheweakmagneticfiel
4、dsinducedbyseawatermovingthroughthegeomagnetic,atwo-stepprocedurewillbefollowed:First,weneedtocalculatethevelocityfieldsofmovingseawaterasaccurateaspossible.So,modelingofthevelocityfieldsofseawaterforwindwavesandshipwakesconstitutesanessentialpartoft
5、hework.Inthispart,bycombiningthephysicalpropertiesofseawaterandourproblemathand,wetaketheseawaterasanidealfluid,namelyanincompressibleandnon-viscousfluid,sothatthevelocitysatisfiesV0.Themotionofseawaterofwindwavesandshipwakescanalsobetakentobeirro
6、tational,sothatthevelocityalsosatisfiesV0andcanbecharacterizedbyapotentialfunctionsuchthatV,whichleadstotheLaplaceequation2=0.Toobtaintheuniquesolutionofthevelocitypotentialforwindwavesandshipwakes,weadopttheclassicalPierson-Moscowitzspectr
7、umtogeneratethesurfacewavestomatchthevelocitypotentialforwindwaves,andusetheshipspectrumtogeneratethesurfaceKelvinwakestomatchthevelocitypotentialforshipwakes,respectively.Secondly,afterthevelocityfieldisresolved,theelectriccurrentdistributioninthese
8、awatermediumcanbefound.ThenwecansolvetheMaxwellequationtoobtaintheinducedelectromagneticfieldunderareasonablestratifiedoceanicconfiguration.Uniquesolutionscanbeextractedbyenforcingtheboundaryconditions,i.e.,thetangentialcomponentsofboththeelectricand