简介:Poly4-vinylphenol(P4VP)/multi-wallcarbonnanotubes(MWNTs)multi-layersensitivefilmsweredepositedoninterdigitatedelectrodesbyairbrushtechnologytodetecttoluenevaporatroomtemperature.Thesurfaceandsectionmorphologiesofthemulti-layerfilmswereobservedbyascanningelectronmicroscope(SEM).Itisfoundthattheresistanceofthesensorincreaseswhenitisexposedtotoluenevaporandtheresponsehasagoodlinearitywiththeconcentrationoftoluene.TheresultsshowthattheP4VP/MWNTsthree-layerfilmsensorshavebettersensingpropertiescomparedwiththetwo-layerfilmsensors.Therelatedsensingmechanismisstudiedindetail.
简介:TheanalysisofsolarcellperformancehasbeendonebysimulatingtheexternalI-Vcharacteristicsofn^+/p/p^+singlecrystalsiliconsolarcellunderhighlightintensityand1.5airmass(AM).Thismethodallowsthemaximizationofsolarcellefficiency.Tofabricatelow-costn^+/p/p^+singlecrystalsiliconsolarcells,solidsourceofdopedphosphorousandboronwasused.
简介:Theletterproposesathree-layermanageablemediadistributionnetworksystemarchi-tecturecalledMSPnet,whichisbasedonSessionInitiationProtocol[1]andPeertoPeer(SIPP2P)technology.MSPnetperformsapplication-levelstructuredDHTroutingandresourcelocationamongdomainsandunstructuredonesindomain.Exceptformediadistribution,itcanbeusedtosupportavarietyofP2Papplications,includingvideobroadcasting,videoondemand,VoIP,etc.MSPnetiscomposedofthreelayers,namely,thesignalcontrollayer,themanagementlayer,andthemediatransportationlayer.TheMSPnetprototypeconsistsoftheSIPserver,themanagementserver,themediaserver,andthenodeUserAgent(UA).Resultsfromaprototypeexperimentinalarge-scaleInternetenvironmentshowthatMSPnetisfeasible,scalableandmanageable.
简介:ThekeyprobleminunstructuredP2Psystemishowtocontrol'Flood'.Somestudiesfocusonconstructingmoreefficienttopologywhileothersfocusonbetterqueryalgorithms.ThispaperpresentsHICUS(HierarchicalInterest-drivenCommunity-basedUnstructuredSystem)motivatedbyabasicthought-whethertheresourcescorrelatewithtopologydistinguishesstructuredandunstruc-turedP2Pessentially.Byintroducinghierarchical'interest',HICUSorganizesaquasi-structuredtopologythroughapuredistributedway,andprovidesanewplatformforqueryalgorithms.Westudytheprocedureandperformanceoftopologyorganization,andthesimulationsshowthatHICUSformsasmall-worldwhichcansignificantlyimprovetheroutingefficiency.
简介:Apeer-to-peer(P2P)networkisadistributedapplicationarchitecturewhichprovidesmanyattractivefeatures,suchasavailability,self-organization,load-balancing,andanonymity.However,P2Pnetworkhascreatedsignificantproblemstonetworkoperatorsbygeneratinglargevolumesofinterautonomoussystem(inter-AS)traffic.FocusingontheBitTorrentswarmingprotocol,thispaperproposesanapproachwhichaimstoreduceP2Pgeneratedinter-AStraffic.Inparticular,theapproachcanreduceinter-AStrafficby50%to70%.Moreover,itcanimprovethedownloadingspeedby60%forthepopulartorrents.Theevaluationshowsthatcontrolledregional-basedcontentsreplicationcaneffectivelyachievethisgoal.Furthermore,theapproachisincrementallydeployable.NetworkregionsinwhichthesystemgetsdeployedcansolvetheirP2Pgeneratedinter-AStrafficproblemsautonomously,i.e.,withoutanyInternetserviceproviders-collaborationandanyrequirement,thesystemcanbedeployedintheentireInternet.
简介:Theoperationprincipleofanarrayedwaveguidegrating(AWG)multiplexerisintroducedandthe4×4AWGwithfollowingdesignparametersisdiscussedindetail,suchasthechoiceofwavelength,theneighboringarrayedwaveguidedistanceΔL,thechannelfrequencyintervalΔf,andthefreespectralrange.Thestructureof4×4AWGisdesignedandtheresultofstimulatedtestisalsogiven.Analysisshowsthatthe4×4AWGischaracterizedbyawidedynamicrange,lowcrosstalk,betterspectrumproperties,andacompactstructure.
简介:基于AlGaN/GaNHEMT工艺制作了大栅宽GaN高电子迁移率晶体管(HEMT)管芯,通过负载牵引及建模技术提取了管芯的输入阻抗、输出阻抗。设计中首先通过L-C网络提升了管芯的输入阻抗、输出阻抗,并通过微带多节阻抗变换器实现了宽带功率分配器及合成器电路的制作,同时还加入了稳定网络,最终实现了50Ω输入输出阻抗匹配。该大功率GaNHEMT内匹配器件采用四胞管芯功率合成技术,总栅宽为4×16mm。在50V漏电压、1ms周期、10%占空比的测试条件下及5.3~5.9GHz频率范围内,输出功率均高于56dBm,最高达到56.5dBm,功率增益均大于12dB,带内功率附加效率超过48.2%。