简介:A2D-directionofarrivalestimation(DOAE)formultiinputandmulti-output(MIMO)radarusingimprovedmultipletemporal-spatialsubspacesinestimatingsignalparametersviarotationalinvariancetechniquesmethod(TS-ESPRIT)isintroduced.InordertorealizetheimprovedTS-ESPRIT,theproposedalgorithmdividestheplanararrayintomultipleuniformsub-planararrayswithcommonreferencepointtogetaunifiedphaseshiftsmeasurementpointforallsub-arrays.TheTS-ESPRITisappliedtoeachsub-arrayseparately,andinthesametimewiththeotherstorealizetheparallellytemporalandspatialprocessing,sothatitreducesthenon-linearityeffectofmodelanddecreasesthecomputationaltime.Then,thetimedifferenceofarrival(TDOA)techniqueisappliedtocombinethemultiplesub-arraysinordertoformtheimprovedTS-ESPRIT.Itisfoundthattheproposedmethodachieveshighaccuracyatalowsignaltonoiseratio(SNR)withlowcomputationalcomplexity,leadingtoenhancementoftheestimatorsperformance.
简介:Thispaperpresentsanewarraystructureforestimatingtwo-dimensional(2-D)direction-of-arrivals(DOAs).ThestructureiscalledY-shapedarray,whichhas10%betteraccuracypotentialthanthenewly-developedL-shapedarray.Agreatmeritisitsabilitytoestimate2-DDOAswhicheverdirectionsthearrivingsignalscomefrom,comparedwithL-shapedarraywhoseperformancedependsonDOAs.Simulationresultsaregiventodemonstratetheperformanceofthenewarray.
简介:Organicmultiplequantumwells(OMQWs)consistingofalternatinglayersoforganicmaterialshavebeenfabricatedfromtris(8-hdroxyquinoline)aluminum(Alq)and2-(4-biphenylyl)-5-(4-tertbutylphenyl)-1,3,3-oxadiazole(PBD)byamultisource-typehigh-vacuumorganicmoleculardeposition.Fromthesmall-angleX-raydiffractionpatternsofAlq/PBDOMQWs,aperiodicallylayeredstructureisconfirmedthroughtheentirestack.TheAlqlayerthicknessintheOMQWswasvariedfrom1nmto4nm.Fromtheopticalaborption,photoluminescenceandelectroluminescencemeasurements,itisfoundthattheexcitonenergyshiftstohigherenergywithdecreasingAlqlayerthickness,ThechangesoftheexcitonenergycouldbeinterpretedastheconfinementeffectsofexcitonintheAlqthinlayers.Narrowingoftheemissionspectrumhasalsobeenobservedfortheelectroluminescentdevices(ELDs)withtheOMQWsstructureatroomtemperature.