简介:摘要:本文主要研究6F.01联合循环机组的热力性能,在此基础上分析朗肯循环热力性能,提出目前影响朗肯效率主要的两个因素为6F.01联合循环机组蒸汽压力以及温度的观点。数据显示如果改变循环机组的蒸汽压力值和温度,朗肯循环效率会随之改变,呈正相关,这一发现为后续优化同类属性的机组蒸汽组参数提供一定的理论依据。
简介:WeldingresearchofA6N01S-T5aluminumalloyprofileforhigh-speedtrainwasdonebyusinglaser-MIGhybridweldingandMIGweldingindividually.Andtheweldappearance,weldingdistortion,mechanicalpropertiesofthejointsandmicrostructureswereanalyzed.Thetestresultsdemonstratedthathigh-efficientweldingfortheprofilecanbeachievedbyusinglaser-MIGhybridwelding,thespeedofwhichcanbeover3.0m/min.Theprocessinghadagoodgapbridgingability,evenifthegapofthebuttjointwasupto2.0mm,agoodweldappearancecanalsobegot.Whilethehybridweldingspeedwasgreaterthan2.5m/min,theweldingdistortionofthelaser-tandemMIGhybridjointswasjustabout33%ofthatoftheMIGjoints,buttheweldingefficiencywasover3timesofMIGwelding.Andtensilestrengthofthehybridjointswas85%ofthatofA6N01S-T5basemetal,9%higherthanthatoftheMIGjoints.Fatiguepropertieswastestedindividuallywithpulsedtensilefatiguemethodintheconditionof1×107lifetime.Thetestresultsdemonstratedthatthefatiguestrengthofthejointswasalittlelowerthanthatofbasematerial,whichcouldbeupto115MPa.Butthefatiguestrengthofhybridweldingjointswas107.5MPa,whichwas23%higherthan87MPaofMIGweldingjoints.
简介:FlameheatingcombinedwithwatercoolingwasusedtostraightenA6N01aluminumalloyweldedjointandeffectofflameheatingpassonitsmicrostructureandmechanicalpropertieswasstudied.ResultsshowedthattheflameinducedtheprecipitationandgrowthoftheMg2SiphaseontheAlsubstrateforthethermalagingA6N01aluminumalloyweldedjoints,thusitledthedecreaseofmicro-hardnessandtensilestrengthoftheA6N01aluminumalloyweldedjointwiththeincreaseoftheheatingpass.However,thefatiguepropertyoftheflameheatedjointwasimprovedbecausetheMg2Siprecipitationhinderedtheinitiationandpropagationofthefatiguecrack.
简介:BeijinghasbeenoneoftheepicentersattackedmostseverelybytheSARS-CoV(severeacuterespiratorysyndrome-associatedcoronavirus)sincethefirstpatientwasdiagnosedinoneofthecity'shospitals.WenowreportcompletegenomesequencesoftheBJGroup,includingfourisolates(IsolatesBJ01,BJ02,BJ03,andBJ04)oftheSARS-CoV.ItisremarkablethatallmembersoftheBJGroupshareacommonhaplotype,consistingofsevenlocithatdifferentiatethegroupfromotherisolatespublishedtodate.Among42substitutionsuniquelyidentifledfromtheBJgroup,32arenon-synonymouschangesattheaminoacidlevel.Rootedphylogenetictrees,proposedonthebasisofhaplotypesandothersequencevariationsofSARS-CoVisolatesfromCanada,USA,Singapore,andChina,gaverisetodifferentparadigmsbutpositionedtheBJGroup,togetherwiththenewlydiscoveredGD01(GD-Ins29)inthesameclade,followedbytheH-UGroup(fromHongKongtoUSA)andtheH-TGroup(fromHongKongtoToronto),leavingtheSPGroup(Singapore)moredistant.ThisresultappearstosuggestapossibletransmissionpathfromGuangdongtoBeijing/HongKong,thentoothercountriesandregions.