简介:Capacitydepletionisanimportantinformationrequiredforplanningofmultipurposereservoirs.Itisacomplexphenomenoninvolvingdiversefieldslikesurfacehydrology,sedimenttransport,variedflowhydraulicsandsoilconsolidation.Properassessmentofcapacityreductionishelpfulinascertainingthelifeofthereservoirandtheprojectbenefitsforcost/benefitanalysis.Inthisstudydimensionallyconsistentequationsfordepositionvolumeandthetrapefficiencyhavebeenobtained.Methodsofobtainingtheparametersinvolvedtheseequationshavealsobeenindicated.Itwasfoundthatthereisgoodagreementwiththefielddata.Itishopedthattheequationsareusefultodesignengineer.
简介:DepletionmodeHEMTwithrefractorymetalsilicideWSigatehasbeende-signedandfabricated.Epicated.Epitaxialmodulationdopingmaterialsweregrownbyahome-madeMBEsystem.Thegatelengthandwidthforlownoisedepletiondeviceswere1.2~1.5μmand2×160μmrespectively.Theelectronmobilityofthefabricateddevicesistypically6080cm^2/V·sat300Kand68000cm^2/V·sat77K.Thesheetelectronconcentrationnsis9×10^11cm^-2,Thesource-draincontactswithAuGeNi/Auwerefabricatedusingevaporatingandlift-offtechnique.tofurtherreducethecontactresistance,thewaferalloyedat520℃for3mininthehydrogen(H2)gas.SchottkygatewasformedusingWSi.Thetranseon-ductanceofthedepletionmodedeviceis110~130mS/mmatroomtemperature,Thede-vicescanbeappliedincommunicationsatelliteatmicrowavefreqencyof3.83GHzandradarreceiverat1.5GHz.Itsnoisefigureisabout2~3dB.
简介:AerosolsampleswerecollectedonboardtheresearchvesselXuelongduringtheFifteenthChineseAntarcticResearchExpedition(CHINAREXV)inNovember1998-April1999andtheFirstChineseArcticResearchExpeditioninJuly-September1999.TheareastraversedbytheexpeditionarycruisesincludetheArcticOcean,thewesternNorthPacificOceanandtheeasternIndianOcean,covering75°N-69°Sand75°E-133°W.AerosolsampleswerealsotakenattheChineseZhongshanStationinEastAntarcticaduringtheCHINAREXV.Analysisofthesamplesyieldedconcentrationsofnon-sea-saltsulfateandothersolublechemicalspeciesinthemarineboundarylayer.Thedatasuggestthatthechemicalcompositionofthemarineaerosolsisinfluencedbythreemajorsources:continentalairmasses,primaryoceanicemissions,andsecondarymarineaerosolsoriginatedfromoceanicemissions.Theresultsshowthat,awingtostronganthropogenicsulfuremissionsfromtheAsiancontinent,non-sea-saltsulfateconcentrationsintheNorthernHemisphere(thewesternNorthPacific)marineaerosolaresignificantlyhigherthanthoseintheSouthernHemisphere(theeasternIndianOcean).Aerosolnon-sea-saltsulfateconcentrationsappeartobeinverselycorrelatedwithaerosolnon-sea-saltchloridewhichshowssignificantlynegativevalues,indicatingthelossofchloridebyseasalts,inmostaerosolsamples.SincegaseousHClmaybeinvolvedinchemicalreactionsthatdepleteatmosphericozoneinthemarineboundarylayer(MBL),highlevelsofacidicnon-sea-salt-sulfatereleasedbyhumanactivitiesinthelowandmid-latitudesoftheNorthernHemispheremaybecomeanimportantpotentialcontributortothelossofatmosphericozoneintheMBL.
简介:Aone-dimensionaltime-dependentphotochemicalmodelisusedtosimulatetheinfluenceofion-producedNOxandHOxradicalsontheAntarcticozonedepletioninpolarnightandpolarspringatalatitudeof73degreessouth.Verticaltransportandnitrogen-oxygen(NOx).hydrogen-oxygen(HOx)productionbyionicreactionshavebeenintroducedintothemodel.NOxandHOxproducedbyprecipitatingionsaretransportedintothelowerstratospherebyverticalmotionandhavesomeeffectsinthedevelopmentoftheAntarcticozonedepletion.Fromwinterthroughspringthecalculatedozonecolumndecreasesto269.4DU.However,thisvalueissignificantlyhigherthanthetotalozoneobservedatseveralAntarcticozonestations.