简介:摘要:当前我国石油长输管道、天然气长输管道、城镇燃气管道、化工管道、电站锅炉管道建设事业蓬勃发展,无损检测是以上工程项目中管道焊接质量控制的重要手段。石油、天然气长输管道无损检测标准主要采用SY/T4109-2013《石油天然气钢质管道无损检测》、城镇燃气管道、化工管道、电站锅炉无损检测标准主要采用NB/T47013-2015《承压设备无损检测》。笔者所在公司为专业的无损检测机构,在工作中,一些无损检测人员经常把以上两个标准的规定弄混淆,或者对标准要求理解错误,因此针对以上两个标准,本文主要就标准在无损检测常规四项检测方法(即射线检测、超声检测、磁粉检测、渗透检测)的异同及运用进行比较分析、便于无损检测工作人员更好的理解标准和运用标准,提高无损检测工作质量和焊接质量。
简介:AgraphGiscalledchromatic-choosableifitschoicenumberisequaltoitschromaticnumber,namelych(G)=χ(G).Ohba’sconjecturestatesthateverygraphGwith2χ(G)+1orfewerverticesischromaticchoosable.ItisclearthatOhba’sconjectureistrueifandonlyifitistrueforcompletemultipartitegraphs.Recently,Kostochka,StiebitzandWoodallshowedthatOhba’sconjectureholdsforcompletemultipartitegraphswithpartitesizeatmostfive.Butthecompletemultipartitegraphswithnorestrictionontheirpartitesize,forwhichOhba’sconjecturehasbeenverifiedarenothingmorethanthegraphsKt+3,2*(k-t-1),1*tbyEnotomoetal.,andKt+2,3,2*(k-t-2),1*tfort≤4byShenetal..Inthispaper,usingtheconceptoff-choosable(orL0-size-choosable)ofgraphs,weshowthatOhba’sconjectureisalsotrueforthegraphsKt+2,3,2*(k-t-2),1*twhent≥5.Thus,Ohba’sconjectureistrueforgraphsKt+2,3,2*(k-t-2),1*tforallintegerst≥1.
简介:<正>Foranoddfunctionf(x)definedonlyonafiniteinterval,thispaperdealswiththeexistenceofperiodicsolutionsandthenumberofsimpleperiodicsolutionsofthedifferentialdelayequation(DDE)(?)(t)=-f(x(t-1)).Byuseofthemethodofqualitativeanalysiscombinedwiththeconstructingofspecialsolutionsaseriesofinterestingresultsareobtainedontheseproblems.
简介:Inthiswork,webrieflydiscussanovelclassofmodifiedgravitylikef(T,TG)gravity.Inthisbackground,weassumethenewagegraphicversionofpilgrimdarkenergyandreconstructf(T,TG)modelsfortwospecificvaluesofs.Wealsodiscusstheequationofstateparameter,squaredspeedofsoundandwDE-wDEplaneforthesereconstructedf(T,TG)models.Theequationofstateparameterprovidesphantom-likebehavioroftheuniverse.ThewDE-wDEplanealsocorrespondstoΛCDMlimit,thawingandfreezingregionsforbothmodels.
简介:Theoneplusone(1+1)modeofhydrosilationreactionofladderlikecis-isotaticpolyallylsilsesquioxane(AllyI-T)andpolyhydrosilsesquioxane(H-T)usingdicyclopentadienylplatinumdichloride(Cp2PtCl2)asthecatalystleadstotheformationofanewpolyorganosiloxane(POS).ThepresenceofnanoscaletubularstructureintheproductPOSwaspreliminarilyprovedbyIR,1H-NMR,differentialscanningcalorimetry(DSC),X-raydiffraction(XRD),gelpermeationchromatography(GPC),atomicforcemicroscopy(AFM)andmolecularsimulation.
简介:ToinvestigatetheimbalancestateofhelperTlymphocytes(Th)andcytotoxicTlympho-cytes(Tc)andtherolesofTh1/Th2/Th3andTc1/Tc2cellsinrenaltransplantationrejection,theper-centagesofthesecellsinperipheralbloodof24casesofrenaltransplantationrecipientswithacutere-jectionandthedynamicchangesoftheCD4/CD8ratioweredeterminedbyflowcytometryanalysis,while30casesofhealthyindividualsweresetupascontrols.Inthesehealthycontrols,thepercentagesoftheTh1,Th2andTh3cellswere(10.45±8.15)%,(5.05±4.15)%and(3.90±3.21)%,andthoseofTc1andTc2cellswere(9.83±7.03)%and(4.51±2.17)%,respectively.However,thepercentagesofTh1andTclcellsinperipheralbloodofthestablerecipientsaftertransplantationwere(7.29±5.62)%and(7.04±5.15)%,showingdefinitereduction,whilethoseofTh2,Th3andTc2cellsshowedsignificantincrease,(6.34±5.67)%,(4.94±4.14)%and(6.86±4.42)%,respectively.Incaseofrecipientswithacuterejection,thepercentagesofTh1andTc1cellsappearedtobe(18.55±13.21)%and(15.84±11.72)%,alsoshowingsignificantincrease,butthoseofTh2,Th3andTc2cellsappearedtobereduced,(4.19±3.62)%,(3.02±2.83)%and(3.88±1.63)%,respectively.Significantdifferencescouldbedetectedamongthesethreegroups(P<0.05).TheCD4/CD8ratioincaseswithacuterejectionwashigherthanthoseofstablerecipients(2.24±0.59vs1.95±0.45),butthatofthestablerecipientsandhealthycontrols(1.98±0.31)showednoanysignificantdifference.Fromtheaboveobservation,itisevidentthatimbalancebetweenTh1,Th2andTh3withTc1andTc2cellsmayexistafterrenaltransplantationandprobably,theim-muneimbalancemaybeinducedthroughthesecretionofcytokinesINF-γbyTh1orTc1cells,Ⅱ-4byTh2andTc2cellsandTGF-βbyTh3.