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150 个结果
  • 简介:Inrecentyears,agreatdealofefforthasbeenmadetoacreateterahertz(THz)waveabsorberbasedonmetamaterials(MM).Metamaterialsabsorbershaveavarietyofpotentialapplicationsincludingthermalemitters,detector,stealthtechnology,phaseimaging,etc.Inthispaper,wefirstlyintroducethebasicstructureandworkprincipleoftheTHzMMabsorbers,andatransmissionlinemodelisdevelopedfordevicesanalysis.ToexpandtheapplicationofTHzabsorbers,dual-bandandbroadbandTHzMMabsorbersaredesigned,fabricated,andmeasured.Attheendofthisarticle,thefuturedevelopmenttrendsofMMabsorbersarediscussed.

  • 标签: 太赫兹 吸收器 双波段 材料 电波吸收体 传输线模型
  • 简介:在这份报纸,我们学习一个乐队抑制nonnegative矩阵因式分解(乐队NMF)问题:为给定的nonnegative矩阵Y,与A作为Y斧子分解它一个nonnegative矩阵和X一个nonnegative块乐队矩阵。这个因式分解模型扩大一个单个低等级subspace模型到几重叠低等级subspaces的混合物,它能不仅提供稀少的表示,而且能从数据集捕获重要组织结构。基于重叠subspace聚类和在附近的subspaces之间的重叠的水平的俘获,二个简单、实际的算法被介绍解决乐队NMF问题。合成数据和真实图象数据的数字实验证明乐队NMF在数据表示提高NMF的性能并且处理。

  • 标签: 因式分解 矩阵和 分解模型 NMF 组织结构 数字实验
  • 简介:The11thChangchunSummerConferenceonChem-istry---TheSeminaronChemistryandPhysicsofRareEarthsinValenceFluctuation,sponsoredbytheChi-neseSocietyofChemistry,theChineseSocietyofRareEarths,JilinSocietyofChemistryandChangchunIn-stituteofAppliedChemistry,AcademiaSinica,washeldinChangchunJuly20-22,1992.ProfessorSuqiang,afamouschemistofChangchunInstituteofAppliedChemistry,lecturedtheplenarymeetingon“TheDependenceofValence

  • 标签: Changchun CHEMIST Jilin SEMINAR MAGNETISM EXPLAIN
  • 简介:Thegeophysicalmodelfunction(GMF)describestherelationshipbetweenbackscatteringandseasurfacewind,sothatwindvectorscanberetrievedfrombackscatteringmeasurement.TheGMFplaysanimportantroleinoceanwindvectorretrievals,itsperformancewilldirectlyinfluencetheaccuracyoftheretrievedwindvector.Neuralnetwork(NN)approachisusedtodevelopaunifiedGMFforC-bandandKu-band(NN-GMF).EmpiricalGMFCMOD4andQSCAT-1areusedtogeneratethesimulatedtrainingdata-set,andGaussiannoiseatasignalnoiseratioof30dBisaddedtothedata-settosimulatethenoiseinthebackscatteringmeasurement.TheNN-GMFemploysradiofrequencyasanadditionalparameter,soitcanbeappliedforbothC-bandandKu-band.Analysesshowthattheσ0predictedbytheNN-GMFiscomparablewiththeσ0predictedbyCMOD4andQSCAT-1.AlsothewindvectorsretrievedfromtheNN-GMFandempiricalGMFCMOD4andQSCAT-1arecomparable,indicatingthattheNN-GMFisaseffectiveastheempiricalGMF,andhastheadvantagesoftheuniversalform.

  • 标签: 神经网络方法 Ku波段 模型函数 地球物理 C波段 基因改造食品
  • 简介:Duetothegoodperformanceoftrackinglowelevationtargetascomparedtomicrowaveandthesuperiorityinpenetratingsmoke,dust,fog,anddrysnowascomparedtoinfrared,aKuandKadualbandexperimentalradarwasdesignedanddeveloped.ThisKuandKadualbandexperimentalradarisanarnplitute-comparisonmonopulsetrackingandguidingradar.Theconstitutionandparametersofthisradarisdescribedinparagraph2.Paragraph3dealswithtwoexperimentsfortestingthetrackingperformancesagainstlowelevationtarget,andgivestheimportantresults.BothKuandKabandhavehightrackingprecisionwhentheytrackhighelevationtargets,whileKabandhasmuchbettertrackingperformancethanKubandwhentheytracklowelevationtargets.Kabandcantrackahelicopter,whoseradarcrosssectionisabout6squaremeters,at40m,20m,10m,andeven5mabovesea.Kubandcanonlytrackthesamehelicopterat160mandhigherabovesea.

  • 标签: MILLIMETER wave RADAR KU and KA
  • 简介:Amethod,whichcanpredictthevalencebandoffsetsatstrainedlayerheterojunctionsunderdifferentstrainsituationsonlybycalculatingbandstructuresanddeformationparametersofthebulkmaterials,issuggested.Theapplicabilityofthismethodisverifiedbycalculationofthevalencebandoffsetsatstrainedlayerheterojuntions,suchasInP/InAs,InP/GaP,GaAs/InAs,GaP/GaAsandAlAs/InAswithvariousstrainconditions.

  • 标签: 应变 异质结 价电子带偏移 平均带能法 畸变位
  • 简介:AkindofDynamicFullBandwidthUtilized(DFBU)allocationalgorithmisintroduced.Thisalgorithmallowsasinglelinktousebandwidthfarbeyonditsfairsharebandwidthinamulti-servicepackettransportingsystem.Threeimportantparametersastheboundonmaximumandminimumbandwidth,themaximumpacketdelayandtheminimumbandwidthutilizationarediscussedandanalyzed.ResultsofexperimentsshowthattheDFBU-algorithmiscapableofmakingasinglelinkinthesystemtouseallthesparebandwidth(uptofull-bandwidth)whiletheperformanceoffairnessandQoSrequirementisstillguaranteed.

  • 标签: 动态分配算法 带宽 DFBU 信息传输
  • 简介:乐队结构和混乱黄铜矿的有效质量光电的材料Cu1xAgxGaX2(X=S,Se)被密度调查功能的理论。特殊quasirandom结构被用来在Cu/Ag地点模仿本地原子混乱。加修正方法的本地密度被采用为所有混合物获得正确半导体乐队差距。bandgap异例能为硫化物和硒化物被看见,在Ag混合物的差距价值比Cu混合物的那些大的地方。乐队差距能为Cu1xAgxGaSe2,并且从为Cu1xAgx煤气的2。乐队差距最小和最大值发生在在x=附近0.5并且x=1,分别地为硫化物和硒化物。以便显示出Cu1xAgx有效的团作为混乱Ag集中的功能被显示出的GaX2,。最后,详细说明了结构被给看澄清基本间接差距的转变需要的声子动量的乐队。这些结果应该在设计高效率的光电的设备是有用的,与更好的吸收和高活动性,由在CuGaX2的做Ag。

  • 标签: 有效质量 能带结构 黄铜矿 无序 密度泛函理论 铜化合物
  • 简介:Thisletterintroducesthedesignideas,simulationandtestresultsofanS-bandklystronwithbandwidthof11%,whichwasdevelopedbytheInstituteofElectronics,ChineseAcademyofSciences(IECAS).Onthepeakpowerlevelof800kW,theefficiencyofklystronismorethan30%;thegainismorethan41dB;theequal-drivingrelativeinstantaneousbandwidthisover11%;theaveragepowerislargerthan8kW,andthepowerfluctuationwithinbandwidthislessthan1.5dB.

  • 标签: S波段速调管 频宽 峰值功率 IECAS
  • 简介:Thispaperdevelopsawide-bandmulti-spectralspaceforcolorrepresentationwithAitkenPCAalgorithm.Thisnovelmathematicalspaceusingthebroad-bandspectramatchingmethodaimsatimprovingtheaccuracyofcolorrepresentationaswellasreducingcostsforprocessingandstoringmulti-spectralimages.Theresultsshowthatthespacecanpresentourexperimentaloriginalspectralspaces(i.e.MunsellcolormattandDIN-6164colorchips)withhighefficiency,andthatthespanningspacewiththreeeigenvectorscanpresenttheoriginalspaceatmorethan98%CSCR,andwhen5eigenvectorsareuseditcancoveralmostthewholeoriginalspaces.

  • 标签: 遥感 彩色图像 计算机 主成分分析 PCA 光谱匹配
  • 简介:Anewultra-wide-band(UWB)hornantennabasedonthenonradiativedielectricwaveguide(NRD-guide)wasproposedtosolvetheproblemofUWBantennas,TEMhornsforexample,generallysufferfromlargesideleakage.Theruleofthetheoreticalselectionofitsparameters,ifNRD-guideisusedastheUWBantennas,isstudiedfirstly,thentheradiationcharacteristicsforanopen-endedNRD-guidearecalculatedbyFDTD(finite-differencetime-domain)method.

  • 标签: 超宽带 NRD波导 FDTD 天线
  • 简介:Theoff-planepropagationofelectromagnetic(EM)wavesinatwo-dimensional(2D)graphitephotoniccrystalstructurewasstudiedusingtransfermatrixmethod.Transmissionspectracalculationsindicatethatsucha2Dstructurehasacommonbandgapfrom0.202to0.2035c/aforbothHandEpolarizationsandforalloff-planeanglesform0°upto90°.Thepresenceofsuchanabsolutebandgapimpliesthat2Dgraphitephotoniccrystal,whichismucheasierandmorefeasibletofabricate,canexhibitsomepropertiesofathree-dimensional(3D)photoniccrystal.

  • 标签: 二维石墨光子晶体 带隙 结构分析 电磁波传播 矩阵变换 光谱分析