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简介：Laser-inducedbreakdownspectroscopy(LIBS)hasattractedextensiveattentionasanewtechniqueforin-situmarineapplication.Inthiswork,theinfluenceofdeep-seahighpressureenvironmentonLIBSsignalswasinvestigatedbyusingacompactLIBS-seasystemdevelopedbyOceanUniversityofChinaforthein-situchemicalanalysisofseawater.TheresultsfromthefieldmeasurementsshowthattheliquidpressurehasasignificanteffectontheLIBSsignals.Higherpeakintensityandlargerlinebroadeningwereobtainedasthepressureincreases.BycomparingthevariationsofthetemperatureandsalinitywiththeLIBSsignals,aweakcorrelationbetweenthemcanbeobserved.Underhighpressureconditions,theoptimallaserenergywashigherthanthatinairenvironment.Whenthelaserenergyexceeded17mJ,theeffectoflaserenergyonthesignalintensityweakened.Thesignalintensitydecreasesgraduallyatlargerdelays.TheobtainedresultsverifiedthefeasibilityoftheLIBStechniqueforthedeep-seain-situdetection,andwehopethistechnologycancontributetosurveyingmoredeep-seaenvironmentssuchasthehydrothermalventregions.

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简介：Theq-profilecontrolproblemintheramp-upphaseofplasmadischargesisconsid-eredinthiswork.Themagneticdiffusionpartialdifferentialequation(PDE)modelsthedynamicsofthepoloidalmagneticfluxprofile,whichisusedinthisworktoformulateaPDE-constrainedop-timizationproblemunderaquasi-staticassumption.Theminimumsurfacetheoryandconstrainednumericoptimizationarethenappliedtoachievesuboptimalsolutions.Sincethetransientdy-namicsispre-givenbytheminimumsurfacetheory,thenthismethodcandramaticallyacceleratethesolutionprocess.Inordertoberobustunderexternaluncertaintiesinrealimplementations,PID(proportional-integral-derivative)controllersareusedtoforcetheactuatorstofollowthecomputationalinputtrajectories.Ithasthepotentialtoimplementinreal-timeforlongtimedischargesbycombiningthismethodwiththemagneticequilibriumupdate.

简介：Improvedperformanceofplasmainrawengineexhausttreatmentisreported.Anewtypeofreactorreferredtoasofcross-flowdielectricbarrierdischarge(DBD)wasused,inwhichthegasflowisperpendiculartothecoronaelectrode.Inrawexhaustenvironment,thecross-flow(radial-flow)reactorexhibitsasuperiorperformancewithregardtoNOxremovalwhencomparedtothatwithaxialflowofgas.Experimentswereconductedatdifferentflowratesrangingfrom2L/minto25L/min.TheplasmaassistedbarrierdischargereactorhasshownencouragingresultsinNO_xremovalathighflowrates.

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简介：Amodellingstudyisperformedtocomparetheplasmaflowandheattransfercharacteristicsoflow-powerarc-heatedthrusters(arcjets)forthreedifferentpropellants:hydrogen,nitrogenandargon.Theall-speedSIMPLEalgorithmisemployedtosolvethegoverningequations,whichtakeintoaccounttheeffectsofcompressibility,LorentzforceandJouleheating,aswellasthetemperature-andpressure-dependenceofthegasproperties.Thetemperature,velocityandMachnumberdistributionscalculatedwithinthethrusternozzleobtainedwithdifferentpropellantgasesarecomparedforthesamethrusterstructure,dimensions,inlet-gasstagnantpressureandarccurrents.Thetemperaturedistributionsinthesolidregionoftheanode-nozzlewallarealsogiven.Itisfoundthattheflowandenergyconversionprocessesinthethrusternozzleshowmanysimilarfeaturesforallthreepropellants.Forexample,thepropellantisheatedmainlyinthenear-cathodeandconstrictorregion,withthehighestplasmatemperatureappearingnearthecathodetip;theflowtransitionfromthesubsonictosupersonicregimeoccurswithintheconstrictorregion;thehighestaxialvelocityappearsinsidethenozzle;andmostoftheinputpropellantflowstowardsthethrusterexitthroughthecoolergasregionneartheanode-nozzlewall.However,sincethepropertiesofhydrogen,nitrogenandargon,especiallytheirmolecularweights,specificenthalpiesandthermalconductivities,aredifferent,thereareappreciabledifferencesinarcjetperformance.Forexample,comparedtotheothertwopropellants,thehydrogenarcjetthrustershowsahigherplasmatemperatureinthearcregion,andhigheraxialvelocitybutlowertemperatureatthethrusterexit.Correspondingly,thehydrogenarcjetthrusterhasthehighestspecificimpulseandarcvoltageforthesameinletstagnantpressureandarccurrent.Thepredictionsofthemodellingarecomparedfavourablywithavailableexperimentalresults.

简介：CO2adsorptiononthesurfaceofhydrotalcite-derivedmixedoxidecatalystswasinvestigatedunderlowpressureglowdischargeplasmainopercindoconditionsviaFT-IRspectroscopy.Nickelcatalystswerepromotedwithvarioustransitionmetalspecies(Ce,Fe,La,Zr)toinfluencetheirphysico-chemicalproperties.FeandZrspeciesweresuccessfullyincorporatedintohydrotalcitebrucitelayers.AftercalcinationformedasinglephasewithNi(Mg,A1)Omixedoxide,whileLaandCespeciesformedseparatephases.ThishadaconsequenceinthedistributionofsurfacebasicsitesaswellasintheaffinitytoCOproduceduponCO2dissociationinplasma.Plasmatreatmentactivatedthesurfaceofpreparedmaterialsandchangedtheirpropertiesviathegenerationofstrongbasicsitesassociatedwithlowcoordinatedsurfaceoxygenanions.Moreover,theCO2adsorptioncapacityofpreparedmaterialsincreasedafterplasmatreatment.

简介：Thecomplexnatureoflaser-materialinteractioncausesnon-stoichiometricablationofalloysamples.Thisisattributedtomatrixeffect,whichreducesanalyzingcapability.Toaddressthisissue,theanalyticalperformanceofthreedifferentnormalizationmethods,namelynormalizationwithbackground,internalnormalizationandthreepointsmoothingtechniquesatdifferentparametersettingsisstudiedforquantificationofAgandZnbyLaserinducedbreakdownspectroscopy(LIBS).TheLIBSspectraoffiveknownconcentrationofsilverzincbinarycompositeshavebeeninvestigatedatvariouslaserirradiances(LIs).CalibrationcurvesforbothAg(I)line(4d^105s^2S1/2→4d^105p^2P1/2at338.28nm)andZn(I)line(4s5s^3S1→4s4p^3P2at481.053nm)havebeendeterminedatLIof5.86×10^10Wcm^-2.SlopesofthesecalibrationcurvesprovidethevaluationofmatrixeffectintheAg–Zncomposites.Withcarefulsamplepreparationandnormalizationaftersmoothingatoptimumparametersetting(OPS),theminimizationofsamplematrixeffecthasbeensuccessfullyachieved.AgoodlinearityhasbeenobtainedinAgandZncalibrationcurveatOPSwhennormalizedthewholeareaofspectrumaftersmoothingandtheobtainedcoefficientsofdeterminationvalueswereR^2=0.995and0.998closerto1.Theresultsofmatrixeffecthavebeenfurtherverifiedbyanalysisofplasmaparameters.BothplasmaparametersshowednochangewithvaryingconcentrationatOPS.However,athighconcentrationofAg,theobservedsignificantchangesinbothplasmaparametersatcommonparametersettingPS-1andPS-2werethegestureofmatrixeffect.Inourcase,thebetteranalyticalresultswereobtainedatsmoothingfunctionwithoptimizedparametersettingthatindicatesitismoreefficientthannormalizationwithbackgroundandinternalnormalizationmethod.

简介：WestudiedthespatialevolutionoftheFe-Niplasmageneratedbythefundamental(1064nm)andsecond(532nm)harmonicsofaQ-switchedNd:YAGlaser.Theexperimentallyobservedlineprofilesoftheneutraliron(FeI)havebeenusedtoextracttheplasmatemperature(Te)usingtheBoltzmannplotmethod,whereastheelectronnumberdensity(Ne)hasbeendeter-minedfromtheStarkbroadening.Inaddition,westudiedthespatialbehaviorofTeandNewiththevariationoflaserenergyforironplasmabyplacingthetargetmaterial(iron-nickelalloy)inairatatmosphericpressureforbothmodesoftheNd:YAGlaser.

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简介：Interactionbetweenhigh-intensitypulsedionbeam(HIPIB)andadouble-layertargetwithtitaniumfilmontopofaluminumsubstratewassimulated.Thetwo-dimensionalnonlinearthermalconductionequations,withthedepositedenergyinthetargettakenassourceterm,werederivedandsolvedbyfinitedifferentialmethod.Asaresult,thetwo-dimensionalspatialandtemporalevolutionprofilesoftemperaturewereobtainedforatitanium/aluminumdouble-layertargetirradiatedbyapulseofHIPIB.Theeffectsofionbeamcurrentdensityonthephasestateofthetargetmaterialsnearthefilmandsubstrateinterfacewereanalyzed.BothtitaniumandaluminumweremeltedneartheinterfaceaRerashotwhentheionbeamcurrentdensityfellintherangeof100A/cm~2to200A/cm~2.

简介：Fe2O3nanoparticlescoatedwithsodiumdodecylbenzenesulphonate(DBS)orcetyltrimethylammoniumbromide(CTAB)werepreparedbyusingamicroemulsionmethodinthesystemwater/toluene.Thenanoparticleswerecharacterizedbymeansoftransmissionelectronmicroscopyandaverageparticlesizesof5.0nmand6.0nmwerefoundforDBS-modifiedandCTAB-modifiednanoparticlesrespectively.Thelocalatomicstructuresoftheseiron(Ⅲ）oxidenanoparticleswereprobedbyusingtheextendedx-rayabsorptionfine-structuretechnique.FeKabsorptionspectrawerecollectedatbeamline4W1BofBeijingSynchrotronRadiationFacility.Astructurealmodelwasproposedfordescribingtheiratomicstructures.TheFe-ObondlengthatthesurfaceofDBS-coatedFe2O3nanoparticleswasfoundtobesimilartothatinbulkFe2O3.buttherewasabout0.04AexpansionfortheCTAB-coatedFe2O3nanoparticles.Onthebasisofthemodelproposedinthispaper,thethicknessesofthesurfacelayerswereestimatedtobe0.5nmand0.7nm.respectively,fortheDBS-coatedandCTAB-coatedFe2O3nanoparticles.Theanharmonicityoftheatomicvibrationandtheasymmetryofatom-pairdistributionwerefoundtobelargeratthesurfaceofthenanoparticlesthaninthebulkmaterial,whiletheDebye-Wallerfactorsarealmostthesameforthesurfaceandthecorepartsofthenanoparticles.Itcanbeconcludedthattheatomicstructureofthenanoparticlesurfaceisordered.buttheatom-paridistributionisasymmetric.