简介:Accuratelymeasuringthedifferentialmolecularabsorptioncrosssectionisthekeytoobtainingahigh-precisionconcentrationofatmospherictracegasesinadifferentialabsorptionlidar(DIAL)system.However,theCO2absorptionlineismeticulousat1.6μm,easilytranslatingandbroadeningbecauseofthechangeoftemperatureandpressure.Hence,measuringtheverticalprofileofatmospherictemperatureandpressuretocalculatetheverticalprofileoftheCO2weightparameterisnecessary.Ingeneral,measuringatmospherictemperatureandpressurehasacertainamountofuncertainty.Therefore,thisstudyproposestheconceptofabalancedon-linewavelength,wherethedifferentialmolecularabsorptioncrosssectionislargerandtheCO2weightparameterisinsensitivetotheuncertaintyofatmospherictemperatureandpressure.Inthisstudy,weanalyzedtheinfluenceofuncertaintyontheCO2weightparameterateverypreselectedwavelength,aswellasdeterminedanappropriatewavelengthnearoneoftheabsorptionpeaks.Ourresultshowsthat1572.023nmshouldbeoneoftheappropriatebalancedonlinewavelengths.ThemeasurementerrorsofthemixingratioofCO2moleculeinthiswavelengthareonly0.23%and0.25%andarecausedby1Ktemperatureerrorand1hPapressureerror,respectively.Thisachievementofabalancedon-linewavelengthwillnotonlydepresstherequirementofthelaser’sfrequencystabilizationbutalsothedemandformeasurementprecisionoftheatmospherictemperatureandpressureprofile.Furthermore,thisstudycanachievetheexactmeasurementoftheverticalprofileofatmosphericCO2basedonanindependentdifferentialabsorptionlaser.
简介:摘要:本文简单地叙述了二氧化碳气体保护焊(以下简称CO2焊)时气孔产生的原因、防止措施和气孔的种类及气孔的危害,对上焊接加工实训课有着重要的指导作用,能有效提高实训课教学质量。
简介:摘要:制冷剂替代的一个研究方向是使用天然工质,而CO2是常用的天然工质之一。本文首先介绍制冷剂的相关物理性质和热力学性质特点,说明CO2作为制冷剂的优越性。然后结合CO2跨临界循环系统介绍结构元器件选型和特点,重点讲述系统非标结构件管路件的选用参考。最后,介绍CO2制冷系统发展过程中面临的挑战和今后发展趋势。
简介:TogaindeepinsightintotheMorphologicaleffectofNixMg1-xOcatalystsonthereactionofCO2reformingwithmethane,wedesignedandfabricatedthreedifferentspatialstructuralNixMg1-xOcatalysts.TheseNixMg1-xOcatalystswithspecificmodelssuchasrod,sheetandsphere,exhibitedvariousactivityandstabilityinCO2reformingreaction.HereinNixMg1-xOnanorodsdisplayedhighercatalyticactivity,inwhichmethaneconversionwasupto72%andCO2conversionwas64%at670°Cwithaspacevelocityof79,200mL/(gcath),comparedwithnanosheetandnanospherecounterparts.Furthermore,bothcatalystsofNixMg1-xOnanorodandnanosheetshowedahighresistancetowardcokedepositionandsinteringofactivesitesintheprocessofCO2reformingofmethane.
简介:Theinterestinthenationallevelsoftheterrestrialcarbonsinkanditsspatialandtemporalvariabil-itywiththeclimateandCO2concentrationshasbeenincreasing.HowtheclimateandtheincreasingatmosphericCO2concentrationsinthelastcenturyaffectthecarbonstorageincontinentalChinawasin-vestigatedinthisstudybyusingtheModifiedSheffeldDynamicGlobalVegetationModel(M-SDGVM).TheestimatesoftheM-SDGVMindicatedthatduringthepast100yearsacombinationofincreasingCO2withhistoricaltemperatureandprecipitationvariabilityincontinentalChinahavecausedthetotalvege-tationcarbonstoragetoincreaseby2.04PgC,with2.07PgCgainedinthevegetationbiomassbut0.03PgClostfromtheorganicsoilcarbonmatter.TheincreasingCO2concentrationinthe20thcenturyisprimarilyresponsiblefortheincreaseofthetotalpotentialvegetationcarbon.Thesefactorialexperimentsshowthattemperaturevariabilityalonedecreasesthetotalcarbonstorageby1.36PgCandprecipitationvariabilityalonecausesalossof1.99PgC.TheeffectoftheincreasingCO2concentrationaloneincreasedthetotalcarbonstorageinthepotentialvegetationofChinaby3.22PgCoverthepast100years.Withthechangingoftheclimate,theCO2fertilizationonChina'secosystemsistheresultoftheenhancednetbiomeproduction(NBP),whichiscausedbyagreaterstimulationofthegrossprimaryproduction(GPP)thanthetotalsoil-vegetationrespiration.OurstudyalsoshowsnotableinterannualanddecadalvariationsinthenetcarbonexchangebetweentheatmosphereandterrestrialecosystemsinChinaduetothehistoricalclimatevariability.
简介:FifteennewabsorptionlinesareobservedwhenstudyingCO2absorptionspectroscopybywavelengthmodulation(WM)techniquewithadistributedfeedbacklaser.TheovertonespectraofCO2around1.31μmandthecorrespondingspectralparameters(i.e.positions,intensities,self-broadeningcoefficients)arepresented.Theintensityoftheweakestlinedetectedis2.25163×10^-27cm^-1/(molecule·cm^-2)atthepressureof5Tort,withacorrespondingabsorptionof3.88×10^-8.
简介:摘要目的观察乌拉地尔对腹腔镜co2气腹导致的高血压的降压作用的临床效果。方法60例全麻下腹腔镜手术病人随机分为对照组(A组,n=30)和乌拉地尔组(B组,n=30),B组于气腹前经静脉推注乌拉地尔0.4mg/kg。记录A组与B组患者气腹前(T1)、气腹后1min(T2)、3min(T3)、5min(T4)、10min(T5)、20min(T6)、30min(T7)及放气后10min(T8)的SBP、DBP、HR的改变。结果A组气腹期间相应时点的SBP、DBP、HR与T1相比明显升高(P<0.01);而B组以上指标相应时点与T1相比无明显改变。结论乌拉地尔能很好地抑制和降低CO2气腹引起的血压变化。