简介：Thispaperdealswiththeproblemofdeterminingtwounknownparametersofsomenonlinearreaction-diffusionmodels.Thesereaction-diffusionmodelsarederivedfromapplicationsinthegroundwaterflowtransport,environmentalsciences,gasdynamics,heatandmasstransfer,industrialautomatizationandsomeotherengineeringtechnologicalfields.Theadjointmethodbasedonthevariationalprincipleisarelativelynewoptimalcontrolmethod.Itisusedintheidentificationoftheunknowndiffusioncoefficient,andsomecoefficientsofthenonlinearsinkorsourcetermsinthesesystems.Atfirst,theproblemistransferredintoanoptimizationproblemofminimizingafunctional,andtheadjointequationsofthegoverningequationsarederivedfromtheadjointmethod.Then,theformulasaregiventocalculatethegradientoftheobjectivefunctionwithrespecttothecoupleofunknownparameters.Atlast,aniterativegradient-basedoptimizationalgorithmispresentedforsolvingtheoptimizationproblem.Anumericalexampleisofferedintheend.Itshowstheeffectivenessoftheproposedapproach.

简介：Undertheeffectsofelectricfieldandchemicalreaction,theproblemofdispersionofaerosolsinapoorlyconductingfluidinachannelissolvedanalyticallyusingthemixturetheorytogetherwitharegularperturbationtechnique.Itisshownthattheaerosolsaredispersedrelativetoaplanemovingwiththemeanspeedofatmosphericfluidaswellasthemeanspeedofagglomerationofaerosolwitharelativediffusioncoefficient,calledtheTaylordispersioncoefficient.Thiscoefficientisnumericallycomputedandtheresultsrevealthatitincreaseswithanincreaseintheelectricnumber,butdecreaseswithincreasingporousparameter.Thephysicalexplanationsforthephenomenaaregiveninthisarticle.