简介:Na离子电池由于他们的低费用和自然许多Na资源为大规模精力存储系统被认为一种有希望的选择到Li离子电池。大努力全球正在做为Na离子电池开发高效的电极材料,它为Na离子电池是批评的。这评论基于Na存储机制为Na离子电池提供阳极材料的全面概述:基于插入的材料,基于合金的材料,基于变换的材料和器官的composites。并且我们总结那些阳极材料的Na存储机制并且讨论他们的失败机制。而且,与那些阳极联系的问题和挑战被指出,并且可行策略为设计高效的阳极材料被建议。根据研究的当前的状态,尽管实质的进步被获得了,为为Na离子电池的合适的阳极材料的搜索仍然是挑战性的。不过,我们相信高效的Na离子电池在不久的将来将为在大规模精力存储系统的实际应用程序是有希望的。
简介:Theexperimentalstudyofultra-wideband(UWB)technology,itsgenerationandon-linemeasurementarepresented.AnexperimentalrepetitiveUWBsystemisdesigned,manufactured,andtested.High-pressuresparkgapswitchanditscomponents,aswellasoilsparkgapswitcharestudiedexperimentallyonthesystem.Experimentalresultsindicatethatthesystemoperatesata200ppsrepetitiveratewithastableperformance.100MWpeakpowerUWBpulsesareobtainedonthesystem.Fast-timeresponsecapacitivedividerisdesignedandfabricated,allowingforanaccuratemeasurementofthehighpowerUWBsignal.ThemainissuesrelatedtothedesignoftheswitchandtheUWBsignalonlinemeasurementarediscussed.
简介:Low-carbonbecomesahigh-frequencyandfashionablewordwhichgetsthegreatestconcernintheworld.Low-carbonreferstoaminimaloutputofgreenhousegasemissionsintothebiosphere,specificallyreferstothegreenhousegascarbondioxide.Toreduceenergyconsumptionofautomobile,moreandmorehighstrengthsteelsareusedbyvehiclecompanies.Tomeettherequestofvehiclecompanies,varioushighstrengthsteelsaredevelopedinsteelcompaniesallovertheworld.Ansteelcanprovide,ultra-lowcarbonbakehardening(BH)steels,dualphase(DP)steelsandtransformation-inducedplasticity(TRIP)steelswiththegradesofunder780MPa,uptonow.AHSSsteelshavemuchdifferentcomposition,microstructureandstrenghtthanconventionalvehiclesteels,sotherearesometroubleinproducingincoldrollingmills,forexample,difficulttojoin,poorthicknessandflatness,accuratetemperatureandvelocitycontrolandsoon.Toreducetheopportunityofstripbreakage,wehavedonemanyweldingexperimentsandspecialresearch.Now,DPandTRIPsteelscanbecontinuouslyproducedinAnsteel.Toassurethicknessandflatnessofstrips,weoptimizedthehotrollingparametertogetlowdeformationresistance,optimizedrollingoiltogetfitfrictionalcoefficientandfixonthetargatrollingcurve.Togetmoreaccurateandrepetitiveresultsovertheproductionshifts,theMathematicalModel(MM)isusedinAnsteel.TheMManalysesinformationtransmittedbyvarioussensorsandtransmitters,comparesthecollecteddatawiththechosenparametersandadjuststhesettingsofthevariouspiecesofequipmenttohoneontheparametersetpoints.Atpresent,thekeyproductiontechnologiesofAHSSweregraspedbycoldrollingmillAnsteel,andAnsteelisthefirstcompanytoapplytheTRIPwiththegradeof780MPa.
简介:Fourtriazoleenantiomersofdiclobutrazol(erythroform)(1),paclobutrazol(erythroform)(2),diniconazole(3)anduniconazole(4)havebeenseparatedbyhighperformanceliquidchro-matography(HPLC)onchiralstationaryphase(CSP)OA-4700.Chromatographicdataandachiralrecongnitionmodelarepresentedfortheseparationofthesepesticideenantiomers.Theinfluenceofcolumntemperatureandcompositionofmobilephasehavebeendescribed.
简介:MechanicalqualityfactorQmisakeycharacteristicparameterofHigh-overtonebulkacousticresonator(HBAR).Theeffectsofstructureparameter(thickness)andperfor?manceparameters(characteristicimpedanceandmechanicalattenuationfactor)ofsubstrate,piezoelectricfilmandelectrodeconstitutingHBARonQmarecarriedout.TherelationshipsbetweenQmandtheseparametersareobtainedbyalumpedparameterequivalentcircuitinsteadofdistributedparameterequivalentcircuitneartheresonancefrequency,andthean?alyticalexpressionsoiQmaregiven.TheresultsshowthatQmincreasesnon-monotonicallywiththecontinuousincreaseofthesubstratethicknessforHBARwithcertainpiezoelectricfilmthickness,anditapproachestothesubstratematerialmechanicalqualityfactorasthesubstratethicknessislarge.QmdecreaseswavilywiththecontinuousincreaseofthepiezoelectricfilmthicknessforHBARwithcertainsubstratethickness.SapphireandYAGwithlowmechanicallossareappropriateasthesubstratetogetalargerQm-TheelectrodelossmustbeconsideredsinceitcanreduceQm-ComparedwithAuelectrode,A1electrodewithlowerlosscanobtainhigherQmwhentheappropriateelectrodethicknessisselected.Inaddition,Qmdecreaseswiththeincreaseoffrequency.TheseresultsprovidethetheoreticalbasisforoptimizingtheparametersofHBARandshowthattrade-oflFsbetweenQmandmustbeconsideredinthedesignbecausetheirchangesareofteninconsistent.
简介:Pantographsystemofhigh-speedtrainsbecomesignificantsourceofaerodynamicnoisewhentravellingspeedexceeds300km/h.Inthispaper,ahybridmethodofnon-linearacousticsolver(NLAS)andFfowcsWilliams-Hawkings(FW-H)acousticanalogyisusedtopredicttheaerodynamicnoiseofpantographsysteminthisspeedrange.Whenthesimulationmethodisvalidatedbyabenchmarkproblemofflowsaroundacylinderoffinitespan,wecalculatethenearflowfieldandfaracousticfieldsurroundingthepantographsystem.Andthen,thefrequencyspectraandacousticattenuationwithdistanceareanalyzed,showingthatthepantographsystemnoiseisatypicalbroadbandonewithmostacousticpowerrestrictedinthemedium-highfrequencyrangefrom200Hzto5kHz.Theaerodynamicnoiseofpantographsystemsradiatesoutwardsintheformofsphericalwavesinthefarfield.Analysisoftheoverallsoundpressurelevel(OASPL)atdifferentspeedsexhibitsthattheacousticpowergrowsapproximatelyasthe4thpoweroftrainspeed.Thecomparisonofnoisereductioneffectsforfourtypesofpantographcoversdemonstratesthatonlycase1canlessenthetotalnoisebyabout3dBasbafflesonbothsidescanshieldsoundwaveinthespanwisedirection.ThecoversproduceadditionalaerodynamicnoisethemselvesintheotherthreecasesandleadtotheriseofOASPLs.
简介:Thisstudyresearchescoldrolledultrahighstrengthmartensiticsteelprocessedbywaterquenching.Itisfoundthatboththequenchingandoverageingtemperaturesgreatlyinfluencethemechanicalpropertiesofmartensiticsteel.Atensilestrengthof1500MPacanbeobtainedfrom0.2%C-1.8%Mnsteelbysoakingat840℃,quenchingat700℃andoverageingat200℃forseveralminutes.Thecontinuouscoolingtransformation(CCT)diagramrevealsthatfullmartensitecanbeobtainedatacoolingrateof100℃/sorhigher;andatacoolingrateof3-10℃/s,austenitebarelydecomposesat700℃.Forsteelwith0.2%carbonandlessmanganese,austenitedecompositionoccursbeforeitiscooledto700℃atacoolingrateof3-10℃/s,whichleadstolowertensilestrength.Itispossibletoreducethemanganesecontentofthe1500MPamartensiticsteelbyincreasingthequenchingtemperature.Toincreasethequenchingtemperature,thecontrolofflatnessduringwaterquenchingbecomesamajorconcern.
简介:Alow-thresholdRamaneffectinakilowattytterbium-dopednarrowbandfiberamplifiersystemisreported.TheRamanStokeslightat1120nmisachievedwiththetotaloutputpowerofonly~400W,indicatingthattheRamanthresholdofthiskilowattcodirectionalpumpedcontinuouswavefiberamplifierismuchlowerthanthepredictedvalueestimatedbytheclassicformula.Tofigureoutthemechanismofthisphenomenon,simulationsbasedonthegeneralstimulatedRamanscattering(SRS)modelareanalyzedindicatingthatthekeyfactoristhecouplingbetweenfour-wavemixing(FWM)andSRS.Thesimulationresultsareingoodagreementwithourexperiments.
简介:Thecoherenceisameasurefortheaccuracyoftheinterferometricphase,andthesyntheticapertureradar(SAR)interferometriccoherenceisaffectedbyseveralsourcesofthedecorrelationnoise.ForthecircularSAR(CSAR)imaginggeometry,thesystemresponsefunctionisintheformoftheBesselfunctionwhichbringsahighsidelobe,andthehighsidelobeofCSARwillbeanimportantfactorinfluencingtheinterferometriccoherence.Theeffectofthehighsidelobeonthecoherenceisanalyzedanddeduced.BasedontheinterferometriccharacteristicsoftheslightdifferenceintheviewinganglesandthepotentialpixeloffsetintheinterferometricSAR(InSAR)images,arelationbetweentheradarimpulseresponseandthecoherencelossfunctionisderived.Fromtherelationalmodel,thecoherencelossfunctionduetothehighsidelobeofCSARisthendeduced,andcomparedwiththatoftheconventionalSAR.ItisshownthatthehighsidelobeofCSARfocusingsignalwillseverelyaffectthebaselinedecorrelationandcoregistrationdecorrelation.SimulationresultsconfirmthetheoreticalanalysisandquantitativelyshowthebaselineandcoregistrationdecorrelationdegradationduetothehighsidelobesofCSAR.
简介:Thecharacteristicsoflow-frequencyelectricalnoise,voltage-current(V-I)andelectricalderivationfor980nmInGaAsP/InGaAs/GaAshighpowerdoublequantumwelllasers(DQWLs)aremeasuredunderdifferentconditions.Thecorrelationofthelow-frequencyelectricalnoisewithsurfacenon-radiativecurrentofdevicesisdiscussed.Theresultsindicatethelow-frequencyelectricalnoiseof980nmDQWLswithhighpowerismainly1/fnoiseandhasgoodrelationwiththedevicesurfacecurrentatlowinjection.
简介:IntroductionMoleculeimprintingtechnologyhasmadegreatprogressinmakingchiralstationaryphasewithpredeterminedchiralselectivityagainstenantiomerssuchasaminoacidandtheirderivatives;sugarandtheirderivatives;naproxenandmethylbenZylamine’-’.Functionalmonomer...