简介:Inordertoimplementlarge-scaleandhigh-betatokamaksimulation,anewalgorithmoftheelectromagneticgyrokineticPIC(particle-in-cell)codewasproposedandinstalledontheGpic-MHDcode[GyrokineticPICcodeformagnetohydrodynamic(MHD)simulation].Inthenewalgorithm,thevorticityequationandthegeneralizedOhm’slawalongthemagneticfieldarederivedfromthebasicequationsofthegyrokineticVlasov,Poisson,andAmperesystemandareusedtodescribethespatio-temporalevolutionofthefieldquantitiesoftheelectrostaticpotentialφandthelongitudinalcomponentofthevectorpotentialAz.Thebasicalgorithmisequivalenttosolvingthereduced-MHD-typeequationswithkineticcorrections,inwhichMHDphysicsrelatedtoAlfvenmodesarewelldescribed.Theestimationofperturbedelectronpressurefromparticledynamicsisdominant,whiletheeffectsofothermomentsarenegligible.Anotheradvantageofthealgorithmisthatthelongitudinalinducedelectricfield,Etz=-■z/■t,isexplicitlyestimatedbythegeneralizedOhm’slawandusedintheequationsofmotion.Furthermore,theparticlevelocitiesalongthemagneticfieldareused(vz-formulation)insteadofgeneralizedmomentums(pz-formulation),hencethereisnoproblemof’cancellation’,whichwouldotherwiseappearwhenAzisestimatedfromtheAmpere’slawinthepz-formulation.ThesuccessfulsimulationofthecollisionlessinternalkinkmodebythenewGpic-MHDwithrealisticvaluesofthelarge-scaleandhigh-betatokamaksrevealedtheusefulnessofthenewalgorithm.
简介:AFluidControlValveBasedontheViscosityIncreaseEffectsofDielectricFluidsCausedbyElectrodesPlantedwithHair-LikeShortFibers(PropositionofaFiberPlantedERValve),ATHERMO-PNEUMATICIN-CHANNELMICROVALVEWITHPDMSDIAPHRAGMFORINTEGRATEDBLOODEXAMINATIONSYSTEMONSILICON.Activecontrolofjetsincrossflow.ASCOinnovativetechnology.Dynamiccompensationofabrasivewaterjetpropertiesthrough3-dimensionaljetcontrol.
简介:NonlinearMHDKelvin-Helmholtz(K-H)instabilityinapipeistreatedwiththederiva-tiveexpansionmethodinthepresentpaperThelinearstabilityproblemwasdiscussedinthepastbyChandrasekhar(1961)andXuetal.(1981).Nagano(1979)discussedthenonlinearMHDK-Hinstabilitywithinfinitedepth.Heusedthesingularperturbationmethodandextrapolatedtheob-tainedsecondordermodifierofamplitudevs.frequencytoseekthenonlineareffectontheinstabilitygrowthrateγ.However,inourview,suchanextrapolationisinappropriate.Becausewhentheinstabili-tysetsin,thegrowthratesofhigher,ordertermsontherighthandsideofequationswillexceedthecor-respondingsecularproducingterms,sotheexpansionwillstillbecomemeaninglessevenifthesecularproducingtermsareeliminated.Mathematicallyspeaking,it’simpossibletoderiveformula(39)whenγ02isnegativeinNagano’spaper.Moreover,evenasearlyasγ02→O+,theexpansionbe-comesinvalidbecausethe2ndordermodifierγ2(inhisformula(56))tendstoinfinity.Thisweak-nessisremovedinthispaper,andtheresultisextendedtothecaseofapipewithfinitedepth.
简介:Inthisarticle,wemainlystudythelocalequationofenergyforweaksolutionsof3DMHDequations.WedefineadissipationtermD(u,B)thatstemsfromaneventuallackofsmoothnessinthesolution,andthenobtainalocalequationofenergyforweaksolutionsof3DMHDequations.Finally,weconsiderthe2Dcaseattheendofthisarticle.
简介:摘要:为更能体现湿喷混凝土适应环保及职业健康的安全性的要求,湿喷混凝土的质量满足现在湿喷技术的要求,依托工程施工中凸显问题,从多方便分析影响喷射混凝土的因素,以及各因素对喷射过程产生危害,通过对各种因素的分析,提出整改措施,以达到更好的控制喷射混凝土质量,提高喷射质量的控制方式、方法。
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简介:WeprovetheexistenceofaweaksolutionforageneralizedquantumMHDequationina2-dimensionalperiodicboxforlargeinitialdata.Theexistenceofaglobalweaksolutionisestablishedthroughathree-levelapproximation,energyestimates,andweakconvergencefortheadiabaticexponentγ>1.