简介:Becausepulserepetitionrateaffecteddirectlythemomentumcouplingcoefficientoftransverselyexcitedatmospheric(TEA)CO2laserpropulsion,adoublepulsetrigger,controllinghighvoltageswitchoflaserexcitationcircuit,wasdesigned.Thepulseintervalrangedbetween5and100ms.Themomentumcouplingcoefficientforair-breathingmodelaserpropulsionwasstudiedexperimentally.Itwasfoundthatthemomentumcouplingcoefficientdecreasedwiththepulserepetitionrateincreasing.
简介:摘要压缩机是国民经济各部门必不可少的设备,应用十分广泛。压缩机绝大多数的故障发生在气阀上,分析了气阀所发生的各类故障及其发生的原因,并提出了合理的防治措施,从而延长了气阀的寿命,增大压缩机的产气量,降低功率消耗,提高了经济效益
简介:Embodiedcarbonintradehasattractedtheattentionofresearchers,developers,andindustryleadersworldwide,asithasbecomeaconsiderablesourceoftradeconflict.BecauseChinaistheworld’sleadingcarbon-emittingcountry,itisimportanttostudythechangetrendsofembodiedCO2inChinesetradetoidentifykeyinfluencingfactors.ThispaperinvestigatesthetradeembodiedCO2inChina,withspecialfocusontheproductionprocessandmaterialsofeachindustrialsectorfrom1990to2013.Thisstudywasconductedbyusinganinput-outputmodel,whichanalyzesthespecificcausesofperiodicwaves.Ourfindingssuggestthatthemachinemanufacturingsectorproducedthelargestshareofemissions,whereasthemetalandnon-metalsectorhasthehighestemissionintensity.Moreover,thetotalemissionquantitiesintradeincreasedfrom612to3331milliontonsin1990to2013,aperiodcharacterizedbydecentralizedtrendsinemissionsexportedtotradepartners.Wealsoemployedthelog-meanDivisiaindex(LMDI)modeltodecomposethecarbonemissionschangesintoexportstructure,exportscale,energystructure,andenergyintensity,andestimatetheinfluenceofthesefactorsatanumberoftimepoints.Wefoundthatenergyintensitycurbsemissionsincrease,andthatexportscaleexpansionisthestrongestdrivingforce.
简介:Chlorofluorocarbons(CFCs)orhydrochlorofluorocarbons(HCFCs)areasmainrefrigerantsusedintraditionalrefrigerationsystemsdrivenbyelectricityfromburningfossilfuels,whichisregardedasoneofthemajorreasonsforozonedepletion(man-maderefrigerantsemission)andglobalwarming(CO2emission).Sopeoplepaymoreandmoreattentiontonaturalrefrigerantsandenergysavingtechnologies.AninnovativesystemcombiningCO2transcriticalcyclewithejectorcycleisproposedinthispaper.TheCO2compressionsub-cycleispoweredbyelectricitywiththecharacteristicsofrelativelyhightemperatureinthegascooler(definedasanintercoolerbytheproposedsystem).Inordertorecoverthewasteheat,anejectorsub-cycleoperatingwiththenaturalrefrigerants(NH3,H2O)isemployed.Thetwosub-cyclesareconnectedbyanintercooler.Thiscombinedcyclejoinstheadvantagesofthetwocyclestogetherandeliminatesthedisadvantages.TheinfluencesoftheevaporationtemperatureinCO2compressionsub-cycle,theevaporationtemperatureintheejectorsub-cycle,thetemperatureintheintercoolerandthecondensationtemperatureintheproposedsystemperformancearediscussedtheoreticallyinthisstudy.Inaddition,someuniquefeaturesofthesystemarepresented.