简介:Hightemperaturesuprerconductor(HTS)currentleadhasanadvantageinreducingelectricpowerconsumptionofarefrigeratorforalargecurrentsuperconductingmagnetsystemsuchasafusiondevice.Afusiondevicerequiresmorethan20pairsoflargecurrentleadsandeachcurrentcapacityisabout60kA.Theconventional60kAcurrentleadneeds100kWelectricpowerforrefrigerationanda2/3reductionisavailablebytheapplicationofaHTScurrentlead.
简介:Thispaperpresentedacontroldesignmethodologyforaprotonexchangemembranefuelcell(PEMFC)generationsystemforresidentialapplications.Thedynamicbehaviorofthegenerationsystemiscomplexinsuchapplications.Acomprehensivecontroldesignisveryimportantforachievingasteadysystemoperationandefficiency.Thecontrolstrategyfora60kWgenerationsystemwasproposedandtestedbasedonthesystemdynamicmodel.Atwo-variablesingleneuronproportional-integral(PI)decouplingcontrollerwasdevelopedforanodepressureandhumiditybyadjustingthehydrogenflowandwaterinjection.Asimilarcontrollerwasdevelopedforcathodepressureandhumiditybyadjustingtheexhaustflowandwaterinjection.Thedesiredoxygenexcessratiowaskeptbyafeedbackcontrollerbasedontheloadcurrent.Anoptimalseekingcontrollerwasusedtotracetheuniqueoptimalpowerpoint.TwonegativefeedbackcontrollerswereusedtoprovideACpowerandasuitablevoltageforresidentialloadsbyapowerconditioningunit.Controlsimulationtestsshowedthat60kWPEMFCgenerationsystemrespondedwellforcomputer-simulatedstepchangesintheloadpowerdemand.Thiscontrolmethodologyfora60kWPEMFCgenerationsystemwouldbeacompetitivesolutionforsystemleveldesignssuchasparameterdesign,performanceanalysis,andonlineoptimization.
简介:Inthispaper,a60kWprotonexchangemembranefuelcell(PEMFC)generationsystemismodeledinordertodesignthesystemparametersandinvestigatethestaticanddynamiccharacteristicsforcontrolpurposes.Toachieveanoverallsystemmodel,thesystemisdividedintofivemodules:thePEMFCstack(anodeandcathodeflows,membranehydration,andstackvoltageandpower),cathodeairsupply(aircompressor,supplymanifold,cooler,andhumidifier),anodefuelsupply(hydrogenvalveandhumidifier),cathodeexhaustexit(exitmanifoldandwaterreturn),andpowerconditioning(DC/DCandDC/AC)modules.Usingacombinationofempiricalandphysicalmodelingtechniques,themodelisdevelopedtosettheoperationconditionsofcurrent,temperature,andcathodeandanodegasflowsandpressures,whichhavemajorimpactsonsystemperformance.Thecurrentmodelisbasedona60kWPEMFCpowerplantdesignedforresidentialapplicationsandtakesaccountoftheelectrochemicalandthermalaspectsofchemicalreactionswithinthestackaswellasflowsofreactantsacrossthesystem.Thesimulationtestsshowthatthesystemmodelcanrepresentthestaticanddynamiccharacteristicsofa60kWPEMFCgenerationsystem,whichismathematicallysimpleforsystemparametersandcontroldesigns.
简介:Recently,RNAprocessinghasemergedasanovelpathwaythatmaycontributetothemaintenanceofgenomestability[1].Alternativesplicingisakeymolecularmechanismforincreasingthefunctionaldiversityoftheeukaryoticproteomes,butitalsooftenalteredincancer.Mountingevidenceindicatesthatalternativesplicing,theprocessthatallowsproductionofmultiplemRNAvariantsfromeachgene,contributestotheheterogeneityofthedisease[2].Althoughthemechanismofalternativesplicingvariantincancerisunclear,thecancer-specificalternativesplicingvariantshavebeenobservedinavarietyofhumancancersandcancercelllinesandhavebeenconnectedtotumorgenesis.
简介:Thetargetofthelargenegativeionsourcebasedonneutralbeaminjection(N-NBI)istoproduceneutralbeamcurrentof22Aandbeampowerof10MWat500keVwithdurationtimeof10s.Sinceitwassuccessfullyoperatedin1996,the5.3MWneutralbeampowerat380keVwithdurationtimeof3shasbeenachieved.Inrecentyearsimprovingandenhancingthebeampoweraregoingon.Severalreasonssuchasplasmanon-uniformity,higherbeamdensityattheupperregioninthebeamprofile,
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简介:用单辊甩带法制备了不含高生物毒性元素的Ti60Zr10Ta15Si15非晶薄带,并在高于其晶化开始温度的不同温度下对该非晶薄带进行了真空退火,研究了该非晶薄带在磷酸盐缓冲溶液(PBS)中的电化学腐蚀行为及热处理对其显微组织及其电化学行为的影响。结果表明,用单辊甩带法制备的Ti60Zr10Ta15Si15金属薄带为完全的非晶态结构,其玻璃转变温度和晶化开始温度分别为759K和833K,经过878K真空热处理后,薄带发生了部分晶化,在非晶的基底上析出了Ti相;经过938K热处理后,薄带发生了完全晶化,晶化相主要由Ti、Si3Ta5和SiZr以及TiSi组成。动电位极化测试表明,该非晶合金在PBS溶液中可表现出较为优异的耐蚀性能,部分晶化可进一步提高该合金的耐蚀性能,而完全晶化的合金抗腐蚀性能明显下降。