简介:theAlternatingSegmentCrank-Nicolsonschemeforone-dimensionaldiffusionequationhasbeendevelopedin[1],andtheAlternatingBlockCrank-Nicolsonmethodfortwo-dimensionalproblemin[2].Themethodshavetheadvantagesofparallelcomputing,stabilityandgoodaccuracy.Inthispaperforthetwo-dimensionaldiffusionequation,thenetregionisdividedintobands,aspecialkindofblock.ThismethodiscalledthealternatingBandCrank-Nicolsonmethod.
简介:Thestudyonthedecaypropertiesofnewisotopeslocatedfarfromthebetastabilitylineiscurrentthefocusofnuclearphysics.ForisotopesintheregionZ>82andN<126,-emissionprevailsasradioactivedecaymodeand-spectroscopyisthemostimportanttooltoobtaininformationonthenuclearstructure.IntheheavynucleiregionwithN=124and126isotones,anintruderstate(h9=2.f7=2)8+basedontheattractiveinteractionoff7=2protonsandf5=2neutronshasbeensignificantlyobserved,whichincreasesthebindingenergyofthisconfigurationwithincreasingprotonnumber.
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简介:Theabinitiogeneralizedgradientapproximation(GGA)+Ustudyofmultiferroic(La0.5Bi0.5)2FeCrO6inpnmastructureandferri-magneticorder,includingHubbardcorrections(U-4.1eV)fortransitionmetal/rareearthd-electronswith20atomscell,showsoptimumlocalmagneticmomentsof(Cr^3+,Fe^3+)equalto(-2.56,4.14)#Bandanidealspin-downbandgapof1.54eV.Tuned-bandgapLa-substituteddoubleoxideperovskitesBFCOshouldexhibitenhancedvisible-lightabsorptionandcarriermobility,thuscouldbeconvenientlightabsorbersandthenefficientalternativestowide-gapchalcopyriteabsorber-basedsolarcellsfailingtoachievehighestpowerconversionefficiencies,andevencompetewiththeirmetal-organichalideperovskitescounterparts.
简介:探讨用等离子体喷涂方法制备降低较高强度材料与U-Nb合金之间的摩擦性能的减磨层的可行性以及这些减磨层的摩擦特性。选用Sn为软涂层,ZrO2为硬涂层。采用SulzerMETCO9M等离子体喷涂机制备了Sn单层、ZrO2单层、Sn/ZrO2双层、Sn+ZrO2混合层等4种涂层。利用CSEM型销盘型摩擦磨损试验机分析了半径为3mm的U-Nb合金对偶销在涂层上滑动时的干摩擦特性,滑动速度分别为0.42,6.4,26.16cm/s。涂层为典型的等离子体喷涂涂层形貌。表面为Sn的涂层颗粒熔合状况和致密性比ZrO2单层好,其粗糙度低,Sn+ZrO2混合涂层表面形貌与ZrO2单层相近。Sn和ZrO2分别以bcc结构的Sn和四方结构ZrO2结构存在。
简介:U-shapedmicro-nanochannelscangeneratesignificantflowdisturbanceaswellaslocallyamplifiedelectricfield,whichgivesitselfpotentialtobemicrofluidicmixers,electrokineticpumps,andevencelllysisprocess.NumericalsimulationisutilizedinthisworktostudythehiddencharacteristicsoftheU-shapedmicro-nanochannelsystem,andtheeffectsofkeycontrollingparameters(theexternalvoltageandpressure)onthedeviceoutputmetrics(current,maximumvaluesofelectricfield,shearstressandflowvelocity)wereevaluated.Alargeportionofcurrentflowingthroughthewholesystemgoesthroughthenanochannels,ratherthanthemiddlepartofthemicrochannel,withitsvalueincreasinglinearlywiththeincreaseofvoltage.Duetothelocaliondepletionnearmicro-nanofluidicjunction,significantlyenhancedelectricfield(asmuchas15foldatV=1VandP0=0)aswellasstrongshearstress(leadingtoelectrokineticflow)isgenerated.Withincreasingexternalpressure,bothelectricfieldandshearstresscanbeincreasedinitially(duetoshorteningofdepletionregionlength),butaresuppressedeventuallyathigherpressureduetothedestructionofiondepletionlayer.Insightsgainedfromthisstudycouldbeusefulfordesigningnonlinearelectrokineticpumpsandothersystems.
简介:Modelinglog-mortalityratesonO-UtypeprocessesandforecastinglifeexpectanciesareexploredusingU.S.data.IntheclassicLee-Cartermodelofmortality,thetimetrendandtheage-specificpatternofmortalityoveragegrouparelinear,thisisnotthefeatureofmortalitmodel.Toavoidthisdisadvantage,O-Utypeprocesseswillbeusedtomodelthelog-mortalityinthispaper.Infact,thismodelisanAR(1)process,butwithanonlineartimedriftterm.BasedonthemortalitydataofAmericafromHumanMortalitydatabase(HMD),mortalityprojectionconsistentlyindicatesapreferenceformortalitywithO-UtypeprocessesoverthosewiththeclassicalLee-Cartermodel.Bymeansofthismodel,thelowboundsofmortalityratesateveryagearegiven.Therefore,lengtheningofmaximumlifeexpectanciesspanisestimatedinthispaper.
简介:Threeheterobinuclearcomplexesweresynthesized,namely[Cu(oxpn)Co(L)2](ClO4)2·xH2O(L=2,2’-bipyridyl(bpy),1,10-phenanthroline(phen),and5-nitro-1,10-phenanthroline(NO2-phen)),whereoxpnrepresentsN,N’-bis(3-aminopropyl)oxam-ido.Basedon1R,elementalanalysis,conductivitymeasurementandelectronicspectra,thesecomplexeswerecharacterizedbyanextendedoxamido-bridgedstructurewithCu(Ⅱ)inaplanarenvironmentandCo(Ⅱ)inaoctahedralenvironment.ThesymmetryofthecationisveryclosetoC2v.Thecomplexeswerealsocharacterizedwithvariabletemperature(4~300K)magneticsusceptibility,andthedatawerefitforthesusceptibilityequationderivedfromspinHamilton,H=-2JS1.S2-DSx12byleastsquarestrategy.Theexchangeintegral,J,wasfoundtobe-22.36cm-1(forbpy);-15.45cm-1(forphen);-19.10cm-1(forNO2-phen),indicatingthatthereisaweakantiferromagneticspin-exchangeinteractionbetweenthemetalions.
简介:TomoreindepthunderstandthedopingeffectsofoxygenonSiGealloys,boththemicro-structureandpropertiesofO-dopedSiGe(including:bulk,(001)surface,and(110)surface)arecalculatedbyDFT+Umethodinthepresentwork.Thecalculatedresultsareasfollows.(i)The(110)surfaceisthemainexposingsurfaceofSiGe,inwhichOimpuritypreferstooccupythesurfacevacancysites.(ii)ForOinterstitialdopingonSiGe(110)surface,theexistencesofenergystatescausedbyOdopinginthebandgapnotonlyenhancetheinfraredlightabsorption,butalsoimprovethebehaviorsofphoto-generatedcarriers.(iii)ThefindingaboutdecreasedsurfaceworkfunctionofO-dopedSiGe(110)surfacecanconfirmpreviousexperimentalobservations.(iv)Inallcases,Odoingmainlyinducestheelectronicstructuresnearthebandgaptovary,butisnotdirectlyinvolvedinthesevariations.Therefore,thesefindingsinthepresentworknotonlycanprovidefurtherexplanationandanalysisforthecorrespondingunderlyingmechanismforsomeoftheexperimentalfindingsreportedintheliterature,butalsoconducetothedevelopmentofμc-SiGe-basedsolarcellsinthefuture.