学科分类
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16 个结果
  • 简介:AVolunterSuportstheElderlyOnFebruary13,1997,Mr.YuXinhua,managerofachain-storeinQingdaoCity,ShandongProvince,decidedtosupport1...

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  • 简介:CyberSpacefirstappearedinthesciencefiction,“Neuromancer”byW.Gibson(1984),thistermwasappliedfordescribingthedesperatevisionofthenearfuture,urbandecay,andneuralimplants.Recently,itisperceivedasawordreferringtoanentirelynewuniverseandthespacevirtuallyexistingwithintheworldwidecomputerInternet.  BecauseCyberSpaceisanewworduptonow,thereisnotadefiniteconceptionaboutityet.Butwecanunderstanditasfollows:CyberSpaceisavirtualspacewhosedatainformationisstoredinthecomputerInternet.CreatinganyvirtualspacedependsontheelectronicaldataintheInternet.ThoughitislessthanacoupleofdecadessinceCyberSpacewasbroughtforward,ithadgrownatsucharemarkablespeedthatithadexpandedtothewidestcomputernetintheworld——Internet.Nowitsincrementstillmaintainsatthedoublerate eachyear,anditisexpectedthattheCyberSpacewillbringanewparadigmofnetworksocietyforthenextcentury. CyberSpacehasspecialspatialcharacteristics.Thephysicaldistanceisnotvalidinthisspace,sowemustuseanewapproachtodescribethedistance.Therearethreemethods.Oneisvaliddistancethatisafunctionaldistance,asthedistancearedescribedbytimeorcost.Thesecondisapsychologicaldistance.Namely,itisasubjectivemeasurementthatpeopleapperceivedistanceastheyareawayfromtheobject.Thethirdisaholisticdistancewhereeachchainhasitsunit.Ontheotherhand,mostCyberSpacedonottakeaccountofthegravity.Infact,thebearing,magnitudeortimeconsequenceofthegravitycanbedefinedatrandomandeasilymodified,however,theunitlengthanddirectionofthe3DvectorchangewiththedifferentpositionsinCyberSpace.Inthissense,thescaleorshapeofasinglebuildingandstreetarenotrestrictedbythespatialcondition.Theonlyfactormaintainingthespatialshapeistopologyreplacingtheorigingravity,systemtime,colorsetandspatialdimensionsetupwiththeownpsychologicals

  • 标签: CYBERSPACE CyberCity GIS VIRTUAL REALITY
  • 简介:Thispaperpresentsanewmethodforsolvingthevibrationofarbitrarilyshapedmembraneswithelasticalsupportsatpoints.Thereactionforcesofdlasticalsupportsatpointsareregardedalunkmownexternalforcesactingonthemembranesthemembranes.Theexaclsolutionoftheequationofmitionisgivenwhichincludestermsrepresentingtheunknownreactionforces.Thefrequencyequationisderivedbytheuseofthelinearrelationshipofthedisplcementswiththereactionforcesofelasticalsupportsatpoints.Finallythecalculatiogformulaeofthefrequencyequationfocircularmembranesareanalyticallyperformedasexamplesandtheinheremfrequenciesofcircularmembraneswithsymmetricelasticalsupportsattwopointsarenumericallycalculated.

  • 标签: circular SYMMETRIC FORMULAE arbitrarily numerically COORDINATES
  • 简介:TheVacuumVessel(VV)systemisanessentialcomponentofKedaTorusforexperiment(KTX),andvariousscenariosmighttakeplaceonit.TheVV’ssupportsshouldbeadequatelystrongtostandagainstvariousloadsonVV,whichmighthappeninextremescenarios.Therefore,thedesignofVVsupportsisverifiedinasingleextremescenarioandissubsequentlyoptimizedinthisreport.ThenumericalsimulationbasedonFiniteElementtheoryisperformedasthemajormethodforanalysisandoptimization.Theelectromagneticforceinpreviousanalysesservesastheloadforthemechanicalanalysesofsupports.Duringtheoptimization,thestressesoftheWsupportsdecreaseremarkablyafterintroducingcotters.Finally,theoptimumdesignhasbeenworkedout.Itsatisfiestherequirementsregardingthestrengthandconvenienceinassembly.

  • 标签: 优化设计 真空容器 KTX 验证 有限元理论 组成部分
  • 简介:ToimplementthespiritofNoticeonWorktoExemptStudentsfromTuitionandMiscellaneousFeesduringCompulsoryEducationinCities,andtoensurecompulsoryeducationincitiesequallyprovidedtochildrenoffarmerworkers,MinistryofFinance

  • 标签: 义务教育 农民工 财政支持 子女 中央 学生工作
  • 简介:LetMbead×dexpansivematrix,andFL2(Ω)beareducingsubspaceofL2(Rd).ThispapercharacterizesboundedmeasurablesetsinRdwhicharethesupportsofFouriertransformsofM-refinableframefunctions.Asapplications,wederivethecharacterizationofboundedmeasurablesetsasthesupportsofFouriertransformsofFMRA(W-typeFMRA)framescalingfunctionsandMRA(W-typeMRA)scalingfunctionsforFL2(Ω),respectively.Someexamplesarealsoprovided.

  • 标签: 傅立叶变换 应用 加细 有界可测集 傅里叶变换 缩放功能
  • 简介:Thesynthesisandpropertiesofcarbonxerogelsarebrieflydescribedinthismini-review,emphasizingthemethodsusedfortuningtheirsurfacechemistryandtexturalpropertiesinordertodesignefficientelectrocatalystsforfuelcells.Inparticular,theroleplayedbythesurfacefunctionalgroupsindeterminingtheloading,dispersion,oxidationstateandstabilityofthemetalphasesisaddressed.

  • 标签: 燃料电池 干凝胶 合成 催化剂 表面官能团
  • 简介:MethacrylicacidfirstwasneutralizedwithanaqueoussolutionofNaOHtopH=6.0~7.0,vinylenecarbonate(VCA)wasaddedtothesolution,thenmonomerswerecopolymerizedinparaffinoilbymeansofreverse-phasesuspensionpolymerizationandhydrophiliccopolymericsupportswereprepared.ThepropertiesofthesupportsweredeterminedusingtrypsinandresultsshowthattheamountofenzymescoupledtothesupportsandthespecificactivityofimmobilizedtrypsinarerelatedtothecontentofVCAstructureunits,reactiontimeandconcentrationofenzymesolution,etc.

  • 标签: Vinylene CARBONATE Methacrylic acid Fixed ENZYME
  • 简介:Inthispaper,varioustechniquesincludingBET,XRD,SEMandXPSwereusedtostudythesinteringofpureandLa2O3-dopedtitania.Theexperimentalresultsshowthatsinteringoftitaniaproceedsviavolumediffu-sion.Addingoflanthanumoxidedecreasestherateofsinteringandhindersthephasetransitionfromanatasetorutilecrystalbystrongsurfaceinteractionbetweenthemixedcrystals(La4Ti9O24,La0.66TiO2.99)andTiO2.

  • 标签: La2O3 TiO2 SINTERING kinetics Thermal stability
  • 简介:Aseriesofhighsurfaceareagraphiticcarbonmaterials(HSGCs)werepreparedbyball-millingmethod.EffectofthegraphiticdegreeofHSGCsonthecatalyticperformanceofBa-Ru-K/HSGC-x(xistheball-millingtimeinhour)catalystswasstudiedusingammoniasynthesisasaprobereaction.ThegraphiticdegreeandporestructureofHSGC-xsupportscouldbesuccessfullytunedviathevariationofball-millingtime.RunanoparticlesofdifferentBa-Ru-K/HSGC-xcatalystsarehomogeneouslydistributedonthesupportswiththeparticlesizesrangingfrom1.6to2.0nm.ThegraphiticdegreeofthesupportiscloselyrelatedtoitsfacileelectrontransfercapabilityandsoplaysanimportantroleinimprovingtheintrinsiccatalyticperformanceofBa-Ru-K/HSGC-xcatalyst.更多还原

  • 标签: 催化性能 碳石墨 催化剂 氨合成 球磨时间 纳米颗粒
  • 简介:ThecorrelationbetweenphasestructuresandsurfaceacidityofAl2O3supportscalcinedatdifferenttemperaturesandthecatalyticperformanceofNi/Al2O3catalystsintheproductionofsyntheticnaturalgas(SNG)viaCOmethanationwassystematicallyinvestigated.Aseriesof10wt%NiO/Al2O3catalystswerepreparedbytheconventionalimpregnationmethod,andthephasestructuresandsurfaceacidityofAl2O3supportswereadjustedbycalciningthecommercialγ-Al2O3atdifferenttemperatures(600–1200C).COmethanationreactionwascarriedoutinthetemperaturerangeof300–600Catdifferentweighthourlyspacevelocities(WHSV=30000and120000mL·g-1h-1)andpressures(0.1and3.0MPa).ItwasfoundthathighcalcinationtemperaturenotonlyledtothegrowthinNiparticlesize,butalsoweakenedtheinteractionbetweenNinanoparticlesandAl2O3supportsduetotherapiddecreaseofthespecificsurfaceareaandacidityofAl2O3supports.Interestingly,NicatalystssupportedonAl2O3calcinedat1200C(Ni/Al2O3-1200)exhibitedthebestcatalyticactivityforCOmethanationunderdifferentreactionconditions.LifetimereactiontestsalsoindicatedthatNi/Al2O3-1200wasthemostactiveandstablecatalystcomparedwiththeotherthreecatalysts,whosesupportswerecalcinedatlowertemperatures(600,800and1000C).ThesefindingswouldthereforebehelpfultodevelopNi/Al2O3methanationcatalystforSNGproduction.

  • 标签: Ni catalyst ALUMINA CO METHANATION synthetic