学科分类
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7 个结果
  • 简介:Themultifractalformalismforsinglemeasureisreviewed.Next,amixedgeneralizedmultifractalformalismisintroducedwhichextendsthemultifractalformalismofasinglemeasurebasedongeneralizationsoftheHausdorffandpackingmeasurestoavectorofsimultaneouslymanymeasures.Borel-CantelliandLargedeviationsTheoremsareextendedtohigherordersandthusappliedforthevalidityofthenewvariantofthemultifractalformalismforsomespecialcasesofmulti-doublingtypemeasures.

  • 标签: HAUSDORFF测度 多重分形 形式主义 混合 评论 偏差定理
  • 简介:Displacednon-Keplerianorbitsaboveplanetarybodiescanbeachievedbyorientatingthesolarsailnormaltothesunline.ThedynamicalsystemstechniquesareemployedtoanalyzethenonlineardynamicsofadisplacedorbitanddifferenttopologiesofequilibriaareyieldedfromthebasicconfigurationsofHill'sregion,whichhaveasaddlenodebifurcationpointatthedegeneratedcase.Thesolarsailnearhyperbolicordegeneratedequilibriumisquiteunstable.Therefore,acontrollerpreservingHamiltonianstructureispresentedtostabilizethesolarsailnearhyperbolicordegeneratedequilibrium,andtogeneratethestableLissajousorbitsthatstaystableinsidethestabilizingregionofthecontroller.ThemaincontributionofthispaperisthatthecontrollerpreservingHamiltonianstructurenotonlychangestheinstabilityoftheequilibrium,butalsomakesthemodifiedellipticequilibriumbecomeuniqueforthecontrolledsystem.Theallocationlawofthecontrolleronthesail'sattitudeandlightnessnumberisobtained,whichverifiesthatthecontrollerisrealizable.

  • 标签: 太阳帆 HAMILTON结构 轨道 退化 双曲 稳定控制器
  • 简介:ThepresentstudyinvestigatesthechangesinTEC(totalelectroncontent)andionosphericscintillationindex(S4)inferredfromtheGNSSdatarecordedattheSCINDAstationofAbidjan(Latitude=5.34°N,Longitude=3.90°W)duringandafterasolarflare.Inthecourseof2014,ayearofhighsolaractivity,three(3)casesofextreme(X1.66)andmoderate(M6.23andM2.13)solarflaresrecordedinthemonthsofSeptemberandDecembereffectsontheionospherehavebeenstudiedusingtheXrayfluxes,themagneticparameters(Vx,Bz,Dst),theionosphericscintillationindexS4andTECanditsROT(timerateofchange).TheROTexhibitsaprominentpeakbetweenten(10)andtwelve(12)minutesaftertheoccurrenceofthemaximumpeakofthetimerateofchangeoftheX-rayfluxemittedduringtheflare.TheROTmaximumvalueoccurssimultaneouslywithanenhancementoftheS4index.DeferredperturbationsofthesolarflareontheTECintheSCINDAstationofAbidjanoccurwithin42to54hoursafteranM-classsolarflareandwithin46to58hoursfollowinganX-Classsolarflare.Themagneticstormsresultedfromtheseflaresshowanincrementof20%onVTECobservedwhencomparedtotheaverageVTEC()computedfromthemostfive(5)quietestdaysoftheselectedmonths.

  • 标签: TEC IONOSPHERIC scintillation SOLAR FLARE X-ray
  • 简介:Inthispaper,amathematicalmodelfortopologyoptimizationoftrussstructureswithconstraintsofdisplacementandsystemreliabilityundermultipleloadingcasesisconstructed.Inordertoavoidthedifficultyofcomputingthestructure’ssystemreliability,asolvingapproachispresentedinwhichthefailureprobabilityofsystemisdividedintothesumofallbars’failureprobabilitybymeansofreliabilitydistribution.Inaddition,bydrawingintothereliabilitysafetyfactorandthefundamen-talrelationshipinstructuralmechanics,allprobabilityconstraintsofdisplacementandstressareequiv-alentlydisplayedasconventionalformandlinearfunctionofthedesignvariables.Theoptimizationproblemwithmultipleconstraintsistreatedbythecompactconstrainttacticsandissolvedbytheim-provedsimplexmethod.Theexamplesshowthattheapproachproposedinthispaperisfeasibleandef-ficient.

  • 标签: MULTIPLE LOADING CASES TRUSS structures systematic
  • 简介:Inthispaper,weconsidernonlinearinfinity-normminimizationproblems.WedeviceareliableLagrangiandualapproachforsolvingthiskindofproblemsandbasedonthismethodweproposeanalgorithmforthemixedlinearandnonlinearinfinity-normminimizationproblems.Numericalresultsarepresented.

  • 标签: 最小化问题 拉格朗日对偶 线性规划 规划论