学科分类
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14 个结果
  • 简介:HAB(harmfulalgalbloom)isaseriousmarineecologicaldisaster.Uptonowthereisnodefiniteconclusionaboutitsmechanismofoccurrence.TheobservationresultsshowthattheHABbreakoutintheXiangshanBaywasmainlycausedbyphysicalconvergencecapacity,andthebreakoutprocesshadnodirectrelationtoeutrophication.AsanewideaitisthoughtthattheprocessoftheHABbreakoutismainlyaphysicalconvergenceoraccumulationprocessinsomeareas.AhypothesisaboutdynamicmechanismoftheHABappearingintheareaofftheChangjiangEstuaryisputforwardaccordingtohydrologyandtopographyandthepastwork,andabreakthroughisexpectedtobemadefordoingfurtherresearch.

  • 标签: 有害藻花 富营养作用 人工生态灾难 水体污染
  • 简介:象腹股沟,纵的堤和防波堤那样的水力的结构在管理和水交通工程在家和国外投射的水里是普通的,它长有由稳固的集体结构的形式统治了。与是的刷子和石头造材料,这种结构有明显的工程效果。然而,它不仅要求巨大的大写的投资,而且在生态的环境上有否定影响。推迟的灵活水坝是一项创新工程措施,和水坝能目前被发现的这种类型的很少理论、试验性的研究。这篇论文学习机制和这个水坝的形状特征并且在三种形式之中为转变获得灵活水坝,漂流快活表示,和条件的动态平衡方程在水下水坝的形状。结果在设计申请是珍贵的并且能为持续开发由于特殊设计哲学,环境上的小否定效果和一致性为未来工作被用作引用。

  • 标签: 坝型 形态特征 柔性 实验 机制 悬浮
  • 简介:Inthispaper,aheavyseafogeventoccurringovertheYellowSeaon11April2004wasinvestigatedbaseduponobservationalandmodelinganalyses.Fromtheobservationalanalyses,thisseafogeventisatypicaladvectioncoolingcase.Seasurfacetemperature(SST)andspecifichumidity(SH)showstronggradientsfromsouthtonorth,inwhichwarmwaterislocatedinthesouthandconsequently,moistureislargerinthesouththaninthenorthduetoevaporationprocesses.Afterfogformation,evaporationprocessprovidesmoremoistureintotheairandfurthercontributestofogevolution.TheseafogeventwasreproducedbytheRegionalAtmosphericModelingSystem(RAMS)reasonably.Therolesofimportantphysicalprocessessuchasradiation,turbulenceaswellasatmosphericstratificationinseafog’sstructureanditsformationmechanismswereanalyzedusingthemodelresults.Therolesoflongwaveradiationcooling,turbulenceaswellasatmosphericstratificationwereanalyzedbasedonthemodelingresults.Itisfoundthatthelongwaveradiativecoolingatthefogtopplaysanimportantroleincoolingdownthefoglayerthroughturbulencemixing.Thefogtopcoolingcanoverpowerwarmingfromthesurface.Seafogdevelopsupwardwiththeaidofturbulence.Thebuoyancyterm,i.e.,theunstablelayer,contributestothegenerationofTKEinthefogregion.However,thetemperatureinversionlayerpreventsfogfromgrowingupward.

  • 标签: 海雾 事件 机制 结构 黄海 辐射冷却
  • 简介:Characteristic modemodel of tropical Pacific Ocean and dynamic mechanism of El NinoZhangXiangdong;HuangShisong;andZhangJing(R...

  • 标签: The PACIFIC model EL Nino
  • 简介:Oysterextractisaneffectivebioactivitycomponent.Ithasabundantnutritionalvalueandantiviral,antitumorandimmunedefensefunctions.Theroleofoysterextractintreatingliverinjuryhasbeenpaidmoreattention.WeuseWistarratstomakealcoholicliverdiseasemodelthroughinjectingalcoholintorats'stomachs.Theseratswererandomlydividedintofivegroups:modelgroup,controlgroup,low-dose,middle-doseandhigh-doseexperimentalgroupwithadoseof0.12gkg-1,0.40gkg-1,and1.20gkg-1alcoholic.Afternineweeks,serumbiomarkers(ALT,AST,TGandTCHO),malondialdehyde(MDA),glutathione(GSH),C3a,C5a,IL-17,TNF-ɑ,anti-MAA-HASIgG,CD3+,CD4+,CD8+,NKcellactivationandzinccontentwereassessed.Theresultsshowedthattheserumbiomarkers(ALT,AST,TGandTCHO),MDAcontent,anti-MAA-HSAIgG,serumC3a,C5aIL-17andTNF-ɑlevelsofoysterextracttreatmentgroupsweresignificantlydecreasedincomparisonwithmodelgroup.Onthecontrary,GSHshowedadversetrend.SerumCD3+,CD4+andNKcellactivationweresignificantlyincreasedinmiddle-dosegroupandhigh-dosegroupcomparedwithmodelgroup,andtherewasdecreaseofCD8+activityinhigh-dosegroup.PlasmaZnlevelwasdecreasedinmodelgroupcomparedwiththatincontrolgroup.Meanwhile,MeanplasmaZnlevelsincreaseddramaticallyfollowingthedoseincreaseofagivenoysterextract.

  • 标签: 提取物 酒精性 牡蛎 组织损伤 保护作用 肝病
  • 简介:Deepwatersedimentsarepronetolosscirculationindrillingduetoalowoverburdengradient.Howtopredictthemagnitudeofleak-offpressuremoreaccuratelyisanimportantissueintheprotectionofdrillingsafetyandthereductionofdrillingcostindeepwater.Startingfromthemechanicalpropertiesofashallowformationandbasedonthebasictheoryofrock-soilmechanics,thestressdistributionaroundaboreholewasanalyzed.Itwasfoundthattherockorsoilonaboreholeisintheplasticyieldstatebeforetheeffectivetensilestressisgenerated,andtheeffectivetangentialandverticalstressesincreaseasthedrillingfluiddensityincreases;thus,tensilefailurewillnotoccurontheboreholewall.Basedontheresultsofstresscalculation,twomechanismsandleak-offpressurepredictionmodelsforshallowsedimentsindeepwaterdrillingwereputforward,andthecalculatedvaluesofthesemodelswerecomparedwiththemeasuredvalueofshallowleak-offpressureinactualdrilling.TheresultsshowthattheMHPS(minimumhorizontalprinciplestress)modelandtheFIF(fracturinginformation)modelcanpredictthelowerandupperlimitsofleak-offpressure.ThePLC(permeablelostcirculation)modelcancomprehensivelyanalyzethefactorsinfluencingpermeableleakageandprovideatheoreticalbasisforleak-offpreventionandpluggingindeepwaterdrilling.

  • 标签: deepwater drilling SHALLOW SEDIMENTS leak-off MECHANISM
  • 简介:Athree-dimensional(3-D)oceanmodeliscoupledwithatwo-dimensional(2-D)seaicemodel,torevisitanonlinearadvectionmechanism,oneofthemostimportantmesoscaleeddygenesismechanismsinthemarginalicezone.Two-dimensionaloceanmodelsimulationssuggestnonlinearadvectionmechanismismoreimportantwhenthewatergetsshallower.Insteadofconsideringtheoceanasbarotropicfluidinthe2-Doceanmodel,the3-Doceanmodelallowstheseaicetoaffectthecurrentdirectlyinthesurfacelayerviaocean-iceinteraction.Itisfoundthatbothmesoscaleeddyandseasurfaceelevationaresensitivetochangesinawaterdepthinthe3-Dsimulations.Theverticalprofileofacurrentvelocityin3-Dexperimentssuggeststhatwhenthewaterdepthgetsshallower,thecurrentmovefasterineachlayer,whichmakestheseasurfaceelevationbenearlyinverseproportionaltothewaterdepthwiththesamewindforcingduringthesametime.Itisalsofoundthatbecauseoftheverticalmotion,themagnitudeofvariationsintheseasurfaceelevationinthe3-Dsimulationsisverysmall,beingonly1%ofthechangeinthe2-Dsimulations.Anditseemstheverticalmotiontobetheessentialreasonforthedifferencesbetweenthe3-Dand2-Dexperiments.

  • 标签:
  • 简介:Onthebasisofdataofdriftingbottles'tracksandthecurrentmeasuredinanchoredstations,aswellastemperatureandsalinityobservedincruiseinvestigationsandcoastalstations,ADCPcurrentdataandAVHRRsurfaceseatemperature(SST)dataonthewesterncoastofGuangdong,syntheticresultsofanalysisshowedthatthecoastalcurrentsinthewestofthemouthoftheZhujiangRiverweremainlywestwardinsummer,whichconstitutedthenorthbranchofcyclonicgyreintheeastoftheQiongzhouStraits.PartofitswaterflowedwestwardintotheBeibuGulfthroughtheQiongzhouStraits.ThecoastalcurrentpatternwasnotidenticalwiththetraditionalcurrentsystemwhichflowedwestwardintheQiongzhouStraitsinwinterandeastwardinsummer.Thesummertime'scoastalcurrentwasalwayswestward,maybetemporarilyturningnortheastonlywhenthesouthwestwindwasstrong.TheimportantcharacteristicsofcoastalcurrentonthewesterncoastofGuangdong,intheQiongzhouStraitsandinthenorthoftheBeibuGulfwereanalyzedandtheirmechanismsalsowereexplained.

  • 标签: 广东 夏季 海岸 琼洲海峡 南海 气旋
  • 简介:TostudytheTaiwanStrait(TS),anunusualseaarea,thenumericalmodelinmarginalseasofChinaisusedtosimulateandanalyzethetidalwavemotioninthestrait.ThenumericalmodelingexperimentsreproducetheamphidromicsystemoftheM2tideinthesouthendoftheTaiwanstrait,andconsequentlyconfirmtheexistenceofthedegenerateamphidromicsystem.Onthisbasis,furtherdiscussionisconductedontheM2systemanditsformationmechanism.ItcanbeconcludedthatthetidalwavesoftheTSisconsistedoftheprogressingwavefromthenorthentranceandthedegenerateamphidromicsystemfromthesouthentrance,inwhichtheprogressingwavefromthenorthentrancedominatesthetidalwavemotioninthestrait.Exceptfortheconvergenteffectcausedbythelandformandboundary,thedegenerateamphidromicsystemproducedinthesouthofthestraitisanotherimportantfactorforthefollowingphenomena:thelargetidalrangeinthemiddleofthestrait,theconcentrativezoneofco-amplitudeandco-phaselineinthesouthofthestrait.ThedegenerateamphidromicsystemismainlyproducedbytheincidentPacificOceantidalwavefromtheLuzonstraitandtheactionbytheshorelineandlandform.Thepositionoftheamphidromicpointiscompelledtomovetowardsouthwestuntildegeneratingbythepowerfulprogressingwavefromthenorthentrance.

  • 标签: 台湾海峡 中国 台湾省 潮汐系统 海洋工程
  • 简介:Biochemicalmechanismofformingtheredtideisdiscussedinthispaper.Theexistenceofalargenumberofnitratesandphosphatesintheeutrophicwateristheprerequisiteofexplosiveincreaseofalgaeandtheformingofredtide.Reductionofeutrophicationisanimportantapproachtopreventingtheredtide.Themethodofdeeptreatmentofthewastewateranditsdenitrificationanddephosphorizationareintroduced,andanewopinionontheredtideformationandfundamentalpreventionisputforward.

  • 标签: 生物化学机制 富营养化 除氮效果 除磷效果 赤潮
  • 简介:Thispaperpresentstwokinematicfailuremechanismsofthree-dimensionalrectangularfootingrestingonhomogeneousundrainedclayfoundationunderuniaxialverticalloadinganduniaxialmomentloading.ThefailuremechanismunderverticalloadingcomprisesaplanestrainPrandtl-typemechanismoverthecentralpartofthelongerside,andthesizeofthemechanismgraduallyreducesattheendsofthelongersideandovertheshortersideasthecornerofrectangularfootingisbeingapproachedwherethedirectionofsoilmotionremainsnormaltoeachcorrespondingsiderespectively.Thefailuremechanismundermomentloadingcomprisesaplanestrainscoopslidingmechanismoverthecentralpartofthelongerside,andtheradiusofscoopslidingmechanismincreaseslinearlyattheendsofthelongerside.Onthebasisofthekinematicfailuremechanismsmentionedabove,theverticalultimatebearingcapacityandtheultimatebearingcapacityagainstmomentormomentultimatebearingcapacityareobtainedbyuseofupperboundlimitanalysistheory.Atthesametime,numericalanalysisresults,Skempton'sresultsandSalgadoetal.'sresultsarecomparedwiththisupperboundsolution.Itshowsthatthepresentedfailuremechanismsandplasticlimitanalysispredictionsarevalidated.Inordertoinvestigatethebehaviorsofundrainedclayfoundationbeneaththerectangularfootingsubjectedtothecombinedloadings,numericalanalysisisadoptedbyvirtueofthegeneral-purposeFEMsoftwareABAQUS,wheretheclayisassumedtoobeytheMohr-Coulombyieldingcriterion.ThefailureenvelopeandtheultimatebearingcapacityareachievedbythenumericalanalysisresultswiththevaryingaspectratiosfromlengthLtobreadthBoftherectangularfooting.ThefailuremechanismsofrectangularfootingwhicharesubjectedtothecombinedverticalloadingVandhorizontalloadingH(VerticalloadingVandmomentloadingM,andhorizontalloadingHandmomentloadingMrespectivelyareobservedinthefiniteelementa

  • 标签: 运动失效机制 矩形桩靴 失效包装 跳跃极限分析
  • 简介:RecentbathymetricchangesintheChangjiangEstuaryundertheinfluenceofartificialregulationengineeringsandbasinreservoirshavebeenanalyzedbasedonthemaritimechartssince1997andrecentfieldworks.Theresultsindicateaslighterosionofthechannelsintheupperandmiddleestuary,continuingdepositionandseawardmoveofthemouthbarcrestandintensifyingerosionatthenearshoreseabed.Itisnoteworthythatthemorphologicalevolutioncausedbyintensivehumanactivitiesdominatesoverthechangesfromnatureprocess.First,theriverbesareerodedoverallintheSouthBranch(SB),theSouthChannel(SC)andtheupperandmiddlereachesoftheNorthChannel(NC).Thenearshoreseabedoutsidetherivermouthisbeingerodedslightly,whichisattributedtothedecliningsedimentsupplyfromtheChangjiangBasinduetotheconstructionoftheThreeGorgesDamupstream.Thesedimentabovetheseabedisveryactiveandcoarsened,meanwhile,sandwavesarebecomingmoredistinct.Second,adepositionoccursintheNorthBrach(NB),themouthoftheNC,themouthbarsoftheNorthPassage(NP)andtheSouthPassage(SP)andespeciallythemainchanneloftheNP,whereitshowsamassivesiltationafterthedeepwaterwayproject.Thereasonsfortherecentchangesarenotonlythedynamicstructureinestuarinemouthbars,butalsothesupplyofsedimentresuspensioninalocalandoffshorearea.Meanwhile,thesevereerosionandsiltationinsomereachesisrelatedtotheconstructionofestuarineengineerings.ItisindicatedthattheChangjiangEstuaryisgraduallyself-adjustedandadaptingtothevaryingnaturalfactorsandintensivehumanactivities.Thestudyonthemechanismofself-regulationoftherecentbathymetricchangesintheChangjiangEstuaryhasimportantandpracticalsignificance.

  • 标签: 长江口 河口坝 河床演变 海底沉积物 深水航道工程 河口拦门沙
  • 简介:Inthispaper,thetotalsugarconcentration,proteinconcentration,lipidyieldandmorphologycharacteristicsofthealgaeresidueweredeterminedtoexplainthemechanismoflipidsextractionfromwetmicroalgaeScenedesmussp.byionicliquidassistedsubcriticalwater.Theresultsshowedsimilarvariationforthesugar,proteinandlipid.However,thetotalsugarwasmoresimilartolipidsyield,sotheresultsshowedthatthereactionbetweenionicliquidandcelluloseandhemicelluloseincellwallwasthemostimportantstepwhichdeterminedthelipidsextrationdirectly.Andthetotalsugarvariationmayberepresentingthelipidsyield.Forlaterlipidsextraction,wecandeterminethetotalsugarconcentrationtopredicttheextractionendproduct.

  • 标签: 油脂提取 离子液体 亚临界水 栅藻 微藻 蛋白质含量
  • 简介:MicrostructureandsubmicrostructureofLeydigcellandSertolicellinthetestisofgonadalprecocityandimmaturationinculturedlargeyellowcroaker,Pseudosciaenacrocea,arestudiedusinghistologyandelectronmicroscopictechnique.Theresultsindicatethatthefinestructureofthetwokindsofcellsindifferentdevelopmentstagespresentsanobviousdifference.ThesmoothendoplasmicreticularandtubularmitochondriaofLeydigcellandSertolicellarewelldevelopedinthetestisofgonadalprecocity,butpoorlydevelopedinthetestisofimmaturation.WesuggestthatthereasonforgonadalprecocityinthelargeyellowcroakermayberelatedtotheearlierdevelopmentandmaturationofLeydigcellandSertolicell.

  • 标签: Pseudosciaena crocea testis LEYDIG cell SERTOLI