简介:Aseriesofidealizedmodelsimulationsareanalyzedtodeterminethesensitivityofmodelresultstodifferentconfigurationsofthelateralboundaryconditions(LBCs)insimulatingmesoscaleshallowconvectionoverhillyterrain.Inthesimulationswithsteadythermalforcingatthemodelsurface,aradiationconditionatbothboundariesisthebestchoiceunderhighwindconditions,andthebestresultsareproducedwhenboththenormalvelocitiesandthetemperaturearetreatedwiththeradiationschemeinwhichthephasespeedisthesamefordifferentvariables.Whenthebackgroundwindspeedisreasonablysmall,theLBCconfigurationwitheithertheradiationorthezerogradientconditionatbothboundariestendstomakethenumericalsolutionunstable.Thechoiceofaconstantconditionattheinflowboundaryandaradiationoutflowboundaryconditionisappropriateinmostcases.Inthesimulationswithdiurnalthermalforcingatthemodelsurface,differentLBCschemesarecombinedtogethertoreducespurioussignalsinducedbytheoutflowboundary.Aspecificationinflowboundarycondition,inwhichthevelocityfieldsattheinflowboundaryareprovidedusingthetime-dependentresultsofasimulationwithperiodicLBCsoveraflatdomain,istestedandtheresultsindicatethatthespecificationconditionattheinflowboundarymakesitpossibletouseasmallermodeldomaintoobtainreasonableresults.Themodelhorizontaldomainlengthshouldbegreaterthanacriticallength,whichdependsonthedomaindepthHandtheanglebetweengravitywavephaselinesandthevertical.Anestimateofminimumdomainlengthisgivenby[(H-zi)/πU]√N2L2x-4π2U2,whereNandUarethebackgroundstabilityandwindspeed,respectively,Lxisthetypicalgravitywavelengthscale,andziistheconvectiveboundarylayer(CBL)depth.
简介:ProcessofsourcedynamicsoftheJingtaiearthquake(M=6.2)Xue-BinDU(杜学彬);Zhi-DeYAN(闫志德)andMing-WuZOU(邹明武)(EarthquakeResearchInstitu...
简介:SongkeWellNo.2,oneofthemainpartofthescientificdrillingprojectinSongliaoBasin,whichwasdrilled7018mandacquiredthepartofcorescontinuouslyfromtheLowCretaceoustotheCarboniferousandthePermianfromthe2843mdeep,canbeconsideredasthedeepestcontinentaldrillingprojectinAsia.Aimingatthefeaturesoflongerwellsections,largerdiametersandmultiplespud-insforcoringofSongkeWellNo.2,thisprojectbrokethroughthe"coringinsmalldiameterandreaminginlargediameter"spud-indrilling-completionprocedureswhicharealwaysusedinlarge-diameter-wellcoringforcontinentalscientificdrillingprojectsindomesticandoverseasandthedrillingmethodofshort-singlecylinderroundtripfootage.Atthesametime,"coringinthesamediameterandcompletingdrillingatonesinglediameter"wasachievedatallφ311mmandφ216mmcoringsectionsofmorethanonethousandmeterslong,high-efficientoperationwith"drillinglongfootagewithdrilltoolscombinedinmulticylinders"wasachievedatdeepcoringsection.Fourworlddrillingrecordswerecreatedwhichincludemorethanathousandmeterscontinuouscoringatφ311mm,andthefootageperroundtripfootageatφ311mm,φ216mmandφ152mmisallmorethan30m,allofthesebreakthroughsreducedatleast300daysforthisproject;moreover,consideringthecharacteristicsofformationsthatthegeothermalgradientishighinthedrilledsectionsandtheinside-welltemperatureisover240℃afterdrillingcompletion,aformate-polymerwater-basedmudsystemwasdevelopedbycompoundingattapulgiteandsodiumbentoniteandbyaddingindependentlydevelopedhigh-temperaturestabilizer,whichcanprovidecriticaltechnicalsupportforsuccessfulwellcompletionat7018minthesuper-high-temperatureenvironmentItisthefirsttimethatthewater-basedmudisoperatedattheworkingtemperaturehigherthan240℃inChina;Besides,consideringthehigh-qualityrequirementoncoresimposedbytheproject,themethod"mechanicalcor
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