简介:高分辨率的浅地震方法是在近的表面描述的最广泛地使用的地球物理的方法。然而,在许多情况中,解释地震图象能是似是而非的。在这篇文章,我们在场因为不适当的限制,源于表面波浪(MASW)的地震思考,嘘波浪地震思考,和多信道的分析调查的P波浪的三案例研究不正确地在调查地点表面或表面下的条件上被解释。一个P波浪思考调查特征首先作为一个浅差错地区被解释,但是当获得通过了道路交叉,它以后决心源于背景噪音的高水平。一个嘘波浪地震思考调查特征被解释是一个反向的蘸滑倒差错,但是指向钻证明它是进基岩表面的深本地的侵蚀。在MASW调查,最后,一个陡峭地蘸的特征首先作为一条基岩山谷被解释。然而,以后探索的钻显示了特征是严重地抑制了大多数应用表面波浪频率乐队的很软的湖沉积的浅层。尽管起始的解释是不正确的,他们在地球物理学者和地质学家之中刺激了讨论并且以前为在科学家之间的有意义的合作和讲话强调了需要,在期间,并且在地球物理的数据获得以后。
简介:—Inthispaper,anonlinearmodelispresentedtodescribewavetransformationinshallowwat-erwiththezero-vorticityequationofwave-numbervectorandenergyconservationequation.Thenonlineareffectduetoanempiricaldispersionrelation(byHedges)iscomparedwiththatofDalrymple'sdispersionrelation.Themodelistestedagainstthelaboratorymeasurementsforthecaseofasubmergedellipticalshoalonaslopebeach,wherebothrefractionanddiffractionaresignificant.Thecomputationre-sults,comparedwiththoseobtainedthroughlineardispersionrelation.showthatthenonlineareffectofwavetransformationinshallowwaterisimportant.Andtheempiricaldispersionrelationissuitableforre-searchingthenonlinearityofwaveinshallowwater.
简介:Basedonthehydrodynamicalfeatureandthetheoreticalvelocityprofilesoftidalflowandwind-inducedflowinshal-lowsea,acomputationalmodelisestablishedforthefirsttime,whichcanseparateobservedvelocityintotidalvelocityandwind-inducedvelocitybyuseoftheleastsquaremethod.Withthemodel,notonlythesurfacevelocitiesoftidalflowandwind-inducedflowareobtained,butalsothebedroughnessheightisdeterminedandthewindvelocityabovethewa-tersurfaceisestimated.Forverificationofthemodel,theobservedvelocityintheYellowRiverEstuaryandthelaborato-rytestisseparated,thenitisappliedtotheYangtzeRiverEstuary.Alltheresultsaresatisfactory.Theresearchresultsshowthatthemodelissimpleinmethod,feasibleinprocessandreasonableinresult.Themodelisavalidapproachtoanalysisandcomputationoffielddata,andcanbeappliedtoseparatetheobservedvelocityinshallowsea;atthesametime,reasonableboundaryconditionsofthesurfaceandbottomcanbeobtainedfortwo-andthree-dimensionalnumericalsimulation.
简介:Athree-dimensionalnumericalmodel,EFDC(environmentalfluiddynamicscode)isappliedtothePamlicoRiverEstuary(PRE)ineasternNorthCarolinaoftheUnitedStatestoexaminethewindimpactonpollutantagedistributionsandresidencetime.Aseriesofmodelexperimentsrepresentingbasecase,remote-wind-inducedwaterlevelset-upandlocalwindscasesareconducted.ModelresultsindicatethatthepollutantmeanageandthesystemresidencetimearefunctionsofgravitationalcirculationinthePRE.Thesystemresponsestoremote-wind-inducedwaterlevelset-uparedifferentindifferentportionsofthePRE.Undersuchcondition,dissolvedsubstancesintheupstreamportionofthePREhaveayoungerageandshorterresidencetime(comparedwiththebasecase),bycontrast,theyhaveaolderageandlongerresidencetimeinthedownstreamportionofthePRE.Upriveranddownriverlocalwindsappeartohaveoppositeimpactsonpollutantagedistributions.ThesubstancesareretainedmuchlongerwithinthePREunderupriverwindthanthoseunderdownriverwind.Themodelresultsalsosuggestthatacross-riverwindsmayleadtolongerresidencetimethroughenhancedturbulencemixing,whichslowsdownthegravitationalcirculationinthePRE.
简介:BasedonKármán’snonlinearfundamentaldifferentialequations,thenewapproach,whichcombinesmodifiediterationmethodwithGalerkin’sone,hasbeenputforwardtosolvenonlinearbendingofshallowsphericalshellwithconcavebaseandclampededgesonthePasternakfoundationunderuniformloadsinthispaper.Mathematicalexpressionofload-deflectionhasbeengiven;furthermore,resultsobtainedareingoodagreementwithexistentones.
简介:TheexistingestimatesofthevolumetransportfromthePacificOceantotheSouthChinaSeaaresummarized,showinganannualmeanwestwardtransport,withtheTaiwanStraitoutflowsubtracted,of3.5±2.0Sv(1Sv=106m3s-1).Resultsofaglobaloceancirculationmodelshowanannualmeantransportof3.9SvfromthePacifictotheIndianOceanthroughtheSouthChinaSea.TheborealwintertransportislargerandexhibitsaSouthChinaSeabranchofthePacific-to-IndianOceanthroughflow,whichoriginatesfromthewesternPhilippineSeatowardtheIndonesianSeasthroughtheSouthChinaSea,aswellasthroughtheKarimataandMindoroStraits.ThesouthwestwardcurrentnearthecontinentalslopeofthenorthernSouthChinaSeaisshowntobeacombinationofthisbranchandtheinteriorcirculationgyre.Thiswinterbranchcanbeconfirmedbytrajectoriesofsatellite-trackeddrifters,whichclearlyshowaflowfromtheLuz6nStraittotheKarimataStraitinwinter.Insummer,theflowintheKarimataStraitisreversed.NumericalmodelresultsindicatethatthePacificwatercanentertheSouthChinaSeaandexittowardtheSuluSea,butnoobservationalevidenceisavailable.Therolesofthethroughflowbranchinthecirculation,waterpropertiesandair-seaexchangeoftheSouthChinaSea,andinenhancingandregulatingthevolumetransportandreducingtheheattransportoftheIndonesianThroughflow,arediscussed.
简介:Basedonthe1stordercnoidalwavetheory,thewavediffractionaroundthepiergroupinshallowwaterisstudiedinthispaper.Theformulasforcalculatingthenonlinearwaveforcesarealsopresentedhere.Inordertoverifythetheoreticalresults,modeltestsareconductedinthewaveflumeinTheStateKeyLaboratoryofCoastalandOffshoreEngineeringlocatedinDalianUniversityofTechnology.TherangeofthewaveparametersintheexperimentsischaracteristicwaveperiodTg/d1/2=8.08-22.86,characteristicwaveheightH/d=0.10.45.Theresultsobtainedfromtheexperimentsagreewiththetheoreticalresultsquitewell.Itisshownthat,inshallowwaterthenonlinearwaveforcesactingonapiergrouparegreaterthanthosecalculatedbylinearwavetheory,thevalueofincrementinwaveforceincreaseswiththeincreasesofthenonlinearityofthewave.Inthewaverangestudiedinthispaper,thenonlinearwaveforcecanreachover4timestheforcecalculatecdbylinearwavetheory.Thus,itissuggestedthat,whenTg/d1/2>8,thewaveforceonthepiersinthepiergroupinshallowwatershouldbecalculatedbyusingthecnoidalwavetheory.
简介:Basedonthesphericalcavityexpansiontheoryintheelastichalfspace,thegroundsurfacemovementcharacteristicsofshallowlyburiedexplosionsareanalyzed.TheresultsshowthattheinducedseismicwaveisalongitudinalwaveinthenearzoneandaRayleighwaveinthefarzone.Themaximumdisplacement(velocity)ofthelongitudinalwaveandtheRayleighwaveareinverselyproportionaltothescaleddistance,andcanbedescribedbyexponentialfunctionwithexponentsequalto1.4and0.5,respectively.Thevibrationfrequenciesofthewaveshavealmostnochange.Thevibrationfrequencyofthelongitudinalwaveapproximatesthenaturalvibrationfrequencyofthecavityinthebrokenarea,andthevibrationfrequencyoftheRayleighwaveisabouthalfthatofthelongitudinalwave.Onthesamereducedburieddepthandreduceddistance,theparticledisplacementisdirectlyproportionaltotheproductoftheboundaryloadingandcavityradius,andisinverselyproportionaltothetransversalwavevelocity.Meanwhile,theparticlevelocityisdirectlyproportionaltotheboundaryloadingandinverselyproportionaltothewavevelocityratio.Inthefarzone,theburieddepthoftheexplosiveonlyhasaslighteffectonthelongitudinalwave,buthasalargereffectontheRayleighwave.
简介:Basedonthe1stordercnoidalwavetheory,thenonlinearwavediffractionaroundacircularcylinderinshallowwaterisstudiedinthispaper.Theequationofthewavesurfacearoundthecylinderisformulatedandbyusingthisformulathewavesurfaceelevationonthecylindersurfacecanbeobtained.Inthispaper,theformulaforcalculatingthecnoidalwaveforceonacircularcylinderisalsoderived.Forthewaveconditionswhichareoftenencounteredinpracticalengineeringdesigns,theratiosofthenonlinearwaveforcestothelinearwaveforcesarecalculated,andtheresultsareplottedinthispaperfordesignpurposes.Inordertoverifythetheoreticalresults,modeltestsareconducted.Aftercomparingthetestresultswiththetheoreticalones,itisconcludedthat,inshallowwater,forthecaseofTg/d1/2>8-10andH/d>0.3,thecnoidalwavetheoryshouldbeusedtocalculatethewaveactiononacylindricalpier.