简介:Au/TbMnO3/YBa2Cu3O7-xcapacitorswerefabricatedonSrTiO3substratesbypulselaserdepositiontechnique,ofwhichelectricpropertieswereinvestigatedinthetemperaturerangefrom25to300K.Bothcurrent-voltagecharacteristicsandjunctionresistanceswithbiasvoltagesshowedremarkabletemperaturedependence,inwhichobviousthermallyexcitedrelaxationprocesseswerefoundbetween150and200K.Atthetemperatureslowerthantheactivationprocess,theleakagecurrentsofthecapacitorswerestudied.Interestingly,athighelectricfield,themechanismoftheleakagewasPoole-Frenkelemission.However,atlowelectricfield,theconductionwasnotOhmic,andideallnJ∝E1/4characteristicswereobserved.Analysisshowedthatthepossibleoriginwasrelatedtotheinherentinhomogeneousnatureofactivationlesspercolatingtransport.
简介:CuO-CeO2catalystswerepreparedbyaureaprecipitationmethodfortheoxidativesteamreformingofethanolatlow-temperature.Thecatalyticperformancewasevaluatedandthecatalystswerecharacterizedbyinductivelycoupledplasmaatomicemissionspectroscopy,X-raydiffraction,temperature-programmedreduction,fieldemissionscanningelectronmicroscopyandthermo-gravimetricanalysis.OverCuOCeO2catalysts,H2withlowCOcontentwasproducedinthewholetestedtemperaturerangeof250–450C.Thenon-noblemetalcatalyst20CuCeshowedhigherH2productionratethan1%Rh/CeO2catalystat300–400Candtheadvantagewasmoreobviousafter20htestingat400C.TheseresultsfurtherconfirmedthatCuO-CeO2catalystsmaybesuitablecandidatesforlowtemperaturehydrogenproductionfromethanol.
简介:Becauseoflimitedresourceofembeddedplatforms,thecomputationalcomplexityofadvancedcontrolalgorithmsraisessignificantchallengesfortheuseofembeddedsystemsincomplexcontrolfield.AScilab/Scicosbasedembeddedcontrollerisdevelopedonwhichvariouscontrolsoftwarecanbeeasilymodeled,simulated,implemented,andevaluatedtomeettheever-expandingrequirementsofindustrialcontrolapplications.BuiltontheCirrusLogicEP9315ARMsystems-on-chipboard,thisembeddedcontrollerispossibletodevelopcomplexembeddedcontrolsystemsthatemployadvancedcontrolstrategiesinarapidandcost-efficientfashion.Duetothefreeandopensourcenatureofthesoftwarepackagesused,thecostoftheembeddedcontrollerisminimized.
简介:Thispapergivesanoverviewonnonlinearporousflowinlowpermeabilityporousmedia,revealsthemicroscopicmechanismsofflows,andclarifiespropertiesofporousflowfluids.Itshowsthat,deviatingfromDarcy’slinearlaw,theporousflowcharacteristicsobeyanonlinearlawinalow-permeabilityporousmedium,andtheviscosityoftheporousflowfluidandthepermeabilityvaluesofwaterandoilarenotconstants.Basedonthesecharacters,anewporousflowmodel,whichcanbetterdescribelowpermeabilityreservoir,isestablished.Thismodelcandescribevariouspatternsofporousflow,asDarcy’slinearlawdoes.Alltheparametersinvolvedinthemodel,havingdefinitephysicalmeanings,canbeobtaineddirectlyfromtheexperiments.
简介:在西南中国的云南的低纬度高地的降水政体服从于在东方亚洲夏天季风和印度夏天之间的相互作用表面山志学的季风,和影响。在它的空间、时间的模式的变化的理解着急地为气候变化设计,水文学影响建模,和地区性、下游的水资源管理被需要。用在最后几十年(1950s2007)的低纬度高地的每日的降水记录,降水的一个时间系列索引,包括年度降水,多雨的天的数字,吝啬的年度降水紧张,雨季的发作的日期,降水的度和时期季节的集中,最高1天、3天、7天的降水,和降水在不同紧张上面为降水多雨的天总计并且数(例如10公里,25公里一没有趋势的预先增白的Mann-Kendall趋势测试然后被用来检测时间系列数据的趋势。结果证明在年度降水和越过低纬度高地的降水趋势的强壮的季节的区别没有重要趋势。弹簧和冬季正在变得更湿,夏天正在变得更干燥。秋天在东方正在变得更干燥并且在西方更湿。作为后果,降水的seasonality稍微正在变弱。雨季和最高的降水的时期的开始趋于更早。同时,低纬度高地也见证不太多雨的天,更强烈的降水,稍微更长中等、重的降水事件,和更经常的极端降水事件。另外,降水趋势的地区性的区别是显著的。这些变化可以与东方亚洲夏天季风变弱并且南方亚洲人夏天季风,以及特殊多山的地面的走廊障碍效果加强被联系。然而,包含的物理机制仍然需要以后被揭开。
简介:Manganesewasextractedfromleachinglow-grademanganeseoreinsulfuricacidmedium.Theeffectsofgranulediameter,leachingtime,liquid/solidratio(V/W)andtheconcentrationofsulfuricacidwereinvestigatedthroughorthogonalandsinglefactorexperiments.Theexperimentalresultsshowedthattheoptimalleachingconditionsare,sizeof0.054mm,120minutesofreactiontime,3(V/W)ofliquid/solidratioand30%oftheconcentrationofsulfuricacid(g/g).Underthoseconditions,theleachingefficiencyis96.73%.Thekineticsoftheleachingprocessisinaccordancewiththecharacteristicsoffractalreaction.
简介:ManyhistoricbuildingsinoldurbancentersinEasternCanadaaremadeofstonemasonryreputedtobehighlyvulnerabletoseismicloads.Seismicriskassessmentofstonemasonrybuildingsisthereforethefirststepintheriskmitigationprocesstoprovideadequateplanningforretrofitandpreservationofhistoricalurbancenters.Thispaperfocusesondevelopmentofanalyticaldisplacement-basedfragilitycurvesreflectingthecharacteristicsofexistingstonemasonrybuildingsinEasternCanada.TheoldhistoriccenterofQuebecCityhasbeenselectedasatypicalstudyarea.Thestandardfragilityanalysiscombinestheinelasticspectraldisplacement,astructure-dependentearthquakeintensitymeasure,andthebuildingdamagestatecorrelatedtotheinducedbuildingdisplacement.Theproposedprocedureconsistsofathree-stepdevelopmentprocess:(1)mechanics-basedcapacitymodel,(2)displacement-baseddamagemodeland(3)seismicdemandmodel.Thedamageestimationforauniformhazardscenarioof2%in50yearsprobabilityofexceedanceindicatesthatslighttomoderatedamageisthemostprobabledamageexperiencedbythesestonemasonrybuildings.ComparisonisalsomadewithfragilitycurvesimplicitintheseismicriskassessmenttoolsHazusandELER.Hazusshowsthehighestprobabilityoftheoccurrenceofnotoslightdamage,whereasthehighestprobabilityofextensiveandcompletedamageispredictedwithELER.Thiscomparisonshowstheimportanceofthedevelopmentoffragilitycurvesspecifictothegenericconstructioncharacteristicsinthestudyareaandemphasizestheneedforcriticaluseofregionalriskassessmenttoolsandgeneratedresults.
简介:Inthispaper,weinvestigateexcitedcharacteristicoftheweaklyinteractingquasi-one-dimensional(1D)andquasi-two-dimensional(2D)Bose–Einsteincondensation(BEC)inharmonicpotentialtrap.Theenergyspectrumandtheanalyticalexpressionofthesoundvelocityareobtainedandanalyzed.Comparedwith3-DimensionalhomogeneousBose-condensedgasoccasion,thesoundvelocityof2DBose-Einsteincondensationinharmonicpotentialtrapissmaller.
简介:Thepreparationofchemicalmanganesedioxide(CMD)fromlow-graderhodochrositeore(LGRO)inXiushan,Chongqing,wasstudiedandimproved,includingleachingwithsulfuricacid,purifying,crystallizinganddecomposingofMnCO3,andrefiningofprimaryMnO2.TheproductwascharacterizedbyX-raydiffraction.Theresultsshowedthattheextractionratio,themanganeserecoveryratioofpurifying,crystallizationandrefiningreached96.8%,93.9%,97.7%and85.4%,respectively.Theoptimumconditionsofrefiningweredescribedasfollows:liquid(H2SO4)/solid(primaryMnO2)ratiowas3L/g,theconcentrationsofNaClOexceeded20%,andreactiontimewas3hours.Undertheaboveconditions,thecontentsofMnO2andMnintheobtainedmanganesedioxidewererespectively85.1%and53.9%.TherefinedMnO2canbeusedasthesupergrademanganesedioxideminepowderinchemicalindustry.TheXRDindicatedthatthestructureoftheproductwasγ-MnO2.
简介:Thispaperdescribestheeffectsofnon-equilibriumairplasmageneratedbyadielectricbarrierdischarge(DBD)onthecombustionoflowheatingvaluefuels.TheexperimentalresultsindicatethatadditionofaverysmallamountofenergytotheairflowintheformofDBDsignificantlyimprovestheflamestability.Moreover,maincombustioncharacteristicssuchasflamepropagationspeed,combustionintensityandleanblow-offlimitsarealsoenhancedbytheeffectofplasma.SomeactiveradicalssuchasexcitedOatomandexcitedN2moleculeareobservedbyspectrographinthedischargearea.BasedontheresultsofnumericalinvestigationwecanconcludethattheseactiveradicalsgeneratedindischargeareacanacceleratetheproductionrateofactiveOHradicalwhichplaysakeyroleintheoxidationprocessoflowheatingvaluefuel,andthusthewholecombustionprocessisaccelerated.
简介:Anumericalinvestigationonover-shroud&inter-shroudleakageflowhasbeencarriedouttoexploretheunderneathflowphysicsatthestageofshroudedLowPressure(LP)turbine.ComparedwiththeNointer-Shroudgap'sLeakageflowModel(NSLM)andWithinter-Shroudgap'sLeakageflowModel(WSLM),theaerodynamiccharacteristicsandtheheattransferperformancehavebeenstudied.Throughtheaerodynamicpointofview,itisconcludedthatduetothepressuredifferencebetweentherotor'spassageandtheover-shroudcavity,inthestream-wisedirection,flowstructurehasbeenmodified,andtheinter-shroudleakageflowmayevencauseflowseparationinthevicinityofthebladepassage'sthroat.Inthecircumferentialdirection,separationflowsappearovertherotor'sshroudsurface(upperplatformoftheshroud).Meanwhile,fromthepointofviewofheattransfer,furtherprovisiononcontourmapsofthenon-dimensionalNusseltnumberrevealsthatthereattachmentofleakageflowwouldenhancetheheattransferratesandendangertherotor'slabyrinthfinsovertheshroud.However,duetothelimitedamountofinter-shroudleakageflow(currentcomputationalmodel),temperaturedistributionvariationalongthebladesurface(neartherotor'stipsection)seemstohaveonlyminorinsignificantdifferences.Attheendofthepaper,theauthorputsforwardsomerecommendationsforthepurposeoffuturesuccessfulturbinedesign.
简介:Thepurposeofthispaperistoclarifythequestionsconcerningstimulationoftheinnovationandthediffusionofenergysavingorlow-carbon.Todoso,thispaperexplainsusingtwocasesofJapan-energysavinginnovationaftertheOilShockandtheecopointssystem.Forthecaseaftertheoilshock,weexplaintheenergysavingtrendaftertheOilShockandthefactorsstatistically.Thenweputforwardthebusinessmodelforthelow-carboneconomy.Furthermore,weanalyzethecaseoftheecopointssystemfrom2009-2011inJapanandexplainthesignificanceofthebusinessmodelfordiffusionofthelow-carbonproducts.
简介:Adirectsynthesisofmethyllevulinatefromcellulosealcoholysisinmethanolmediumundermildcondition(180210C)catalyzedbyextremelylowconcentrationsulfuricacid(0.01mol/L)andtheproductisolationweredevelopedinthisstudy.Effectsofdifferentprocessvariablestowardsthecatalyticperformancewereperformedasafunctionofreactiontime.Theresultsindicatedthatsulfuricacidconcentration,temperatureandinitialcelluloseconcentrationhadsignificanteffectsonthesynthesisofmethyllevulinate.Anoptimizedyieldofaround50%wasachievedat210Cfor120minwithsulfuricacidconcentrationof0.01mol/Landinitialcelluloseconcentrationbelow100g/L.Theresultingproductmixturewasisolatedbyadistillationtechniquethatcombinesanatmosphericdistillationwithavacuumdistillationwheren-dodecanewasaddedtohelpdistilltheheavyfraction.Thelightfractionincludingmainlymethanolcouldbereusedasthereactionmediumwithoutanysubstantialchangeintheyieldofmethyllevulinate.ThechemicalcompositionandstructuraloflowerheavyfractionwerecharacterizedbyGC/MS,FTIR,1H-NMRand13C-NMRtechniques.Methyllevulinatewasfoundtobeamajoringredientoflowerheavyfractionwiththecontentover96%.Thispathwayisefficient,environmentallybenignandeconomicalfortheproductionofpurelevulinateestersfromcellulose.
简介:ATibetanozonelowwasfoundinthe1990saftertheAntarcticozonehole.Whetherthisozonelowhasbeenrecoveringfromthebeginningofthe2000sfollowingtheglobalozonerecoveryisanintriguingtopic.WiththemostrecentmergedTOMS/SBUV(TotalOzoneMappingSpectrometer/SolarBackscatterUltraViolet)ozonedata,theTibetanozonelowanditslong-termvariationduring1979-2010areanalyzedusingastatisticalregressionmodelthatincludestheseasonalcycle,solarcycle,quasi-biennialoscillation(QBO),ENSOsignal,andtrends.TheresultsshowthattheTibetanozonelowmaintainsandmaybecomemoresevereonaverageduring1979-2010,comparedwithitsmeanstateintheperiodsbefore2000,possiblycausedbythestrongerdownwardtrendoftotalozoneconcentrationovertheTibet.Comparedwiththeozonevariationoverthenon-Tibetanregionalongthesamelatitudes,theTibetanozonehasalargerdownwardtrendduring1979-2010,withamaximumvalueof-0.40±0.10DUyr1inJanuary,whichsuggeststhestrengtheningoftheTibetanozonelowincontrasttotherecoveryofglobalozone.RegressionanalysesshowthattheQBOsignalplaysanimportantroleindeterminingthetotalozonevariationovertheTibet.Inaddition,thelong-termozonevariationovertheTibetanregionislargelyaffectedbythethermal-dynamicalproxiessuchasthelowerstratospherictemperature,withitscontributionreachingaround10%ofthetotalozonechange,whichisgreatlydifferentfromthatoverthenon-Tibetanregion.
简介:Howtoeffectivelyreducetheenergyconsumptionoflarge-scaledatacentersisakeyissueincloudcomputing.Thispaperpresentsanovellow-powertaskschedulingalgorithm(LTSA)forlarge-scaleclouddatacenters.Thewinnertreeisintroducedtomakethedatanodesastheleafnodesofthetreeandthefinalwinneronthepurposeofreducingenergyconsumptionisselected.Thecomplexityoflarge-scaleclouddatacentersisfullyconsider,andthetaskcomparsoncoefficientisdefinedtomaketaskschedulingstrategymorereasonable.Experimentsandperformanceanalysisshowthattheproposedalgorithmcaneffectivelyimprovethenodeutilization,andreducetheoverallpowerconsumptionoftheclouddatacenter.