简介:对埋地钢质管道由于与高压交流输电线路、高压交流电力机车等的平行、交叉和靠近铺设,所带来的交流腐蚀的分析,说明对在建或运行中的埋地管道,必须重视来自高压交流输电线路的交流干扰以及来自高压交流电气化轨道的干扰的检测、排查、与评估。本文介绍了国际上对交流干扰危险性新的分类标准,以及在交流干扰存在下通过接地排流、或隔直流排流等手段来减缓交流干扰的电压后,又如何通过基于直流电流密度与交流电流密度指标来评价管道的阴极保护的有效性,这也是近年来国外研究与探讨的主要课题。通过本文介绍,希望加强国内关于交流干扰的检测与研究的重视,并进一步制定与国际同步的标准规范,以指导行业内的设计、检测行为,保证埋地油气管道的安全运行。通过本文介绍,希望促进国内关于交流干扰的检测与研究的重视,并进一步制定与国际同步的标准规范,以指导行业内的设计、检测行为,保证埋地油气管道的安全运行。
简介:BasedonthetechniqueforpreparingLaCl3viadirectpyrolysisofrareearthchloridesolution,ajetpyrolysisreactorwasdesignedandtheintra-reactortemperatureandchemicalreactionswerenumericallysimulatedusingcomputationalfluiddynamics(CFD)technique.Theresultsshowthattheflowratevariationatthefuelinletdoesnotlargelyaffectthetemperatureinthereactor,whiletheincreaseinexternalpressureatthematerialinletrapidlydecreasestheaveragetemperature,Venturitemperature,andoutlettemperature.TheCH4andO2insidethereactorarecombustedcompletely,andwhenthematerialinletpressureis\90Pa,theLaCl3isfullypyrogenated.ThecontentsofCO2,La2O3,andHClfluctuateneartheVenturitubeandfinallystabilize.La2O3contentattheoutletisinatop-to-bottomgradient.
简介:Thecorrosionbehaviorandanti-corrosionmechanismoftheZn-Ni-Al2O3compositecoatingwereinvestigatedbySEM,EDSandXPS.TheresultsindicatethatthecorrosiontypeoftheZn-Ni-Al2O3coatingsinneutral5wt.%NaClsolutionisuniformcorrosion.ThepresenceofcompactanduniformlydispersednanoaluminaparticlessubstantiallyinhibitsthecorrosionofZn-Ni-Al2O3compositecoatings.Intheinitialcorrosionstage,thecorrosiveproductsofZn-NimatrixformacompactZnCl2·4Zn(OH)2layer.Withthedevelopmentofcorrosion,somenanoaluminaparticlesareembeddedandformaNienrichmentlayer.InNienrichmentlayer,NipresentsasNiandNiO.
简介:Fe2O3和ZnO的粉末混合物是在一家高精力的行星的球工厂的milled综合ZnFe2O4和X光检查粉末diffractometry被用来获得阶段,雏晶尺寸和Fe2O3和ZnFe2O4的microstrain的相对内容。Fe2O3的格子常数被房间精炼方法获得。macrokinetics和事的结构进化被学习,结果证明ZnFe2O4的mechanochemical合成的动力学过程适合Avrami-Erofe'ev模型并且被成核生长机制,和结构的macrokinetics理论在燃烧合成研究控制区域能被用来也描述运动过程。
简介:WehavecalculatedtheelectronicstructuresofCo2FeAl1-xSix(101)surfaceusingfirst-principlesmethodbasedonthedensityfunctionaltheory.Becauseofthesurfaceeffect,theminorityspinbandgapattheFermileveldisappearsatthesurfaceofbulkCo2FeAl1-xSix.However,beneaththesurface,theminorityspingapopensattheFermilevel,whichindicatesthattheelectronicstructuresofCo2FeAl1-xSix(101)be-comeclosetothatofbulkphase.Accordingly,theCo2FeAl1-xSix(101)surfaceisacompositetri-layerstructurethatcorrespondstotheweakeningofhalf-metallicpropertyinCo2FeAl1-xSixfilms.Eventhough,thespinpolarizationofCo2FeAl1-xSix(101)surfaceisstilllargerthanthatofCo2FeAlorCo2FeSimaterials,makingCo2FeAl1-xSixapromisingspintronicsmaterial.
简介:IntheautomaticCO2arcwelding,thealterationoftheverticaldistancebetweentheweldingtorchandtheworkpiecehasastrongeffectontheweldingparameterssuchasweldingcurrentandvoltage,withtheresultthattheappearanceandqualityofweldarenotsteady.Toweakentheinfluenceofthedistancealteration,amethodisputforwardinthepaper.Themethodisthatthealternatewire-feedcontrolisusedforcompensatingtheweldingcurrent.Onthebasisoftheoreticalanalysis,astaticnumericalmodelforalternatewire-feedcontrolisestablished.Theexperimentsshowthatthemodel-basedregulationofthewirefeedratecancompensatetheweldingcurrentandensuretheappearanceofweld.Whenthealterationofverticaldistancebetweenthetorchandtheworkpieceisgreater,notonlyisthewirefeedrateregulated,buttheoutputvoltageofthepowersourceisadjustedtoensuretheappearanceandqualityofweld.
简介:NanostructuredandconventionalAl2O3-13wt%TiO2coatingsweremanufacturedbyairplasmaspray.FrictionandwearbehaviorsofcoatingswereinvestigatedatroomandelevatedtemperaturesusinganSRVweartestmachine.Thenanostructuredcoatinghas"tworegions"microstructure,whiletheconventionalcoatinghastypicallayeredmicrostructurewithobviousinterfacesamongsplats.Thecoefficientoffrictiondecreaseswithrisingoftemperaturebecauseoftheformationoftribo-layeratelevatedtemperatures.Thewearresistanceofthenanostructuredcoatingsishigherthanthatoftheconventionalcoating,andthewearthresholdofappliedloadis30Nforconventionalcoatingand40Nfornanostructurecoating.Thewearresistancedifferenceisrelatedtothe"tworegions"microstructureofnanostructurecoating,whichcouldbluntorbranchthecrackspropagation.Inourtestranges,thewearratesrisingaremoresensitivewiththeappliedwearloadrisingthanwiththetemperaturerising.