简介：Byemployingaradiofrequency(RF)feedbackchain,theself-interferencecanbecanceledefficientlyinco-timeco-frequencyfullduplex(CCFD).However,theevitablesignalcrosstalkwhichiscausedbytheimperfectRFfeedbackchainisolationusuallydamagestheself-interferencecancelation(SIC)performance.Todealwiththisproblem,firstly,weanalyzetheimpactofRFfeedbackchainisolationonSICperformance.ThenadigitalpreprocessingschemewithRFfeedbackchainisproposedinthemultiple-antennaCCFDarchitecture.Usingbothanalyticalandexperimentalmethods,wefindthattheproposedschemeachievesabetterperformanceonSIC.

简介：Asignalwaveformrecoverymethodbasedonthecoprimearrayisinvestigatedtoextractthewaveformofthedesiredsignalfromspatialinterferencesinnarrowbandscenarios.Thedirectionofarrivals(DOAs)ofthedesiredsignalandinterferencesignalsareestimatedwiththecompressivesensingapproachbasedonanglegrids,andthesignalpowertogetherwiththenoisepowerareestimated.Thereafter,amodifiedsteepestdescent(SD)methodisderivedtorecoverthewaveformofthedesiredsignalandinterferencesutilizingtheestimatedpoweranddirections.Therecoveredwaveformofthedesiredsignalistheoutputoftheproposedmethod.Thesituationinwhichthesignalsarenotonthepredefinedanglegridsisalsoconsidered.TheDOAsestimatedpredefinedanglegridsisalsoconsidered.TheDOAsestimatedlikelihood(ML)angleestimation.Comparedtotheexistingbeamformingmethodsonco-primearray,theproposedmethodcanobtainthewaveformofthedesiredsignal.Simulationresultsdemonstratethattheproposedmethodcanachievegoodperformanceinsignalwaveformrecoveryandoutputsignaltonoiseratio.

简介：Anovelpre-ionizationschemeofhelicaltransverse-pulsedpre-ionizationinalongitudinaldischargeCO2laserispresented.Thelasertubeismadeofglasswithinnerdiameterof7.5mmanddischargelengthof50cm.Thelaserperformancecharacteristicsasfunctionsofparameters,suchaspressure,chargingcapacitanceandappliedvoltage,areinvestigated.Comparedwiththesamelaserstructurewithoutpre-ionization,themaximumpulseenergyimprovesby23%,theoptimumelectro-opticalefficiencyincreasesby31%,andthespecificoutputenergyreaches26J/(L·atm).

简介：Cu-andCo-substitutedNiZnferritethinfilms,Ni0.4-xZn0.6CuxFe2O4andNi0.5Zn0.5CoxFe2-xO4(0≤x≤0.2),aresynthesizedbysol-gelprocess.ThecrystallographicandmagneticpropertiesofCu-andCo-substitutedNiZnferritethinfilmshavebeeninvestigated.ThelatticeparameterdecreaseswithCusubstitutionandincreaseswithCosubstitution.ThesaturationmagnetizationdecreasesandthecoercivityincreaseswiththeincreaseofCusubstitution.Moreover,thesaturationmagnetizationgraduallyincreaseswiththeincreaseofCosubstitutionwhenx≤0.10,butdecreaseswhenx>0.10.Meanwhile,thecoercivityinitiallydecreaseswiththeincreaseofCosubstitutionwhenx≤0.10,butincreaseswhenx>0.10.

简介：Inthispaper,quartzcrystalmicrobalance(QCM)gassensorscoatedwithpolyehtyleneimine(PEI)wasutilizedforcarbondioxide(CO2)detection.Thesensingmechanismisbasedontheavailabilityofreversibleacid-basereactionsbetweenCO2moleculesandPEIatroomtemperature.TheexperimentalresultsrevealedthatthePEI/starchsensorexhibitedmuchhighersensitivitythanthatofpurePEI,andshowedapproximatelinearityoveraconcentrationregionrangingfrom500ppmto8000ppm.Theinfluenceofhumidityhadalsobeeninvestigated.Furthermore,theresponseandrecoverytimedeceasedastheoperationtemperaturesincreased.Finally,sensitivitylossafterconservationforseveraldaysandreversibilityofthesensorshadbeendiscussed.

简介：半导体封装尺寸的缩小、功率的增大以及开关速度的提高，这些推动着电子器件冷却方法的发展。在现在的先进电子系统中，现有的导热界面材料成为散热的瓶颈。工程师们希望用按照热管理要求设计的最优金属，他们需要知道有些什么方案可以选用，才能把最好的导热界面材料（TIM）用到他们设计的应用系统中，加强散发热量通路中的薄弱环节。

简介：1前言SnPB合金镀层已广泛地应用于电子元器件和印制板等电子业领域,用作抗蚀行保护和可焊性涂层。随着印制板图形和电子元器件的微细化,作为SnPb合金镀覆方法的电镀SnPb法和浸渍熔融SaPb法存在着SnPb涂层厚度不均匀,容易造成短路和热变形等缺点,已远远不能适用。与此对比,化学镀SnPb合金则可以弥补电镀法和浸渍法的不足,近年来的化学镀SnPb合金的应用日趋广泛。本文就化学镀PbSn合金

简介：概述了电子安装工业中理想的替代用无Pb焊料合金Veromet347和Veromet349,具有优良的微构造,金属间化合物厚度,焊料湿润性,机械特性,抗拉应变和蠕变特性等。

简介：Dispersionandnonlineardistortionhaveaneffectontransmissionperformancesofopticalfibertransimissionsystems,Theschemesofdispersioncompensationandnonlineardistortionself-compensationintelecom-CATVco-networktransmissionsystemsarereported,followedbyinvestigationon(1)theimpactofdispersioncompensationfiber(DCF)onfibernonlineareffectswithacascadeoferbium-dopedfiberamplifiers(EDFAs)anddifferentdispersioncompensationschemes,(2)theimpactofthecomplexonthetotalnonlineardistortioninducedbyEDFAgaintiltandthelightsource.Asaresult,dispersioncompensationoptimalschemeandEDFAnegativegaintiltaresuggestedasasolutiontodispersioncompensationoptimalschemeandEDFAnegativegaintiltaresuggestedasasolutiontodispersioncompensationandthenonlineardistortionself-compensation.

简介：近几年,电子产品朝轻,薄,短,小化迅速发展,印制线路板也随着这股潮流朝向高密度封装方向发展。尤其是积层板总数的增加和导通孔以及连接盘的小径化也日益显著。对于积层线路板而言,用来加工层间连接的盲通孔(BVH)的激光方法取决于导通孔和连接盘径。激光器分为CO2激光和UV-Yag激光两种。导通孔径为60μm以上时,则一般用CO2激光加工。由于铜在CO2激光的波长(9.3μm～10.3μm)领域中的吸收比很低,因此"保形法"(在表面铜箔上,蚀刻出需要的加工孔径(开铜窗),再以激光打掉树脂)成为了现在的主流。然而,由于保形法需要蚀刻开铜窗,因此增加了形成图形的工序,而且导通孔的定位取决于下层的定位标记,容易发生错位。随着积层板层数的增加,导通孔和连接盘的小径化发展,越来越需要提高加工速度和定位精度。因此,同时对铜和树脂进行加工的"直接钻孔法"开始被关注。直接钻孔法是根据格柏数据进行导通孔的定位,因此,即使导通孔/连接盘径越趋小型化,也不会发生错位,是一种能够推进多层化,高密度化的先端技术。本文讲述了以直接钻孔法形成高可靠度导通孔时所需的技术和药品。

简介：Aimingattheproblemofthepeaktoaveragepowerratio（PAPR）incoherentopticalorthogonalfrequencydivisionmultiplexing（CO-OFDM）,ahybridPAPRreductiontechniqueoftheCO-OFDMsystembycombiningiterativepartialtransmitsequence（IPTS）schemewithmodifiedclippingandfiltering（MCF）isproposed.Thesimulationresultsshowthatatthecomplementarycumulativedistributionfunction（CCDF）of104,thePAPRofproposedschemeisoptimizedby1.86dBand2.13dBcomparedwiththoseofIPTSandCFschemes,respectively.Meanwhile,whenthebiterrorrate（BER）is10^-3,theopticalsignaltonoiseratio（OSNR）areoptimizedby1.57dBand0.66dBcomparedwiththoseofCFandIPTS-CFschemes,respectively.

简介：在平行缝焊、储能焊、玻璃熔封、激光焊、合金焊料熔封等密封工艺中,合金焊料密封是高可靠密封的优选工艺。文章针对合金焊料密封工艺中常遇到的密封强度、密封内部气氛、焊缝及盖板耐腐蚀、薄形封装易短路等问题,介绍了通过合金焊料盖板的选择,从而控制密封强度、密封内部气氛、耐蚀性能和电性能等的质量。

简介：1.前言铜及铜合金具有较高的强度、优异的机械加工性、导电性、导热性、焊接性及耐腐蚀性等特性,在电力、电子、石油化工及军工等工业领域得到极为广泛的应用和发展.在电化学序列中,铜具有比氢更高的正电极电位,因此在一般的腐蚀性介质(空气、水及非氧化性酸等)中,铜具有较高的热力学稳定性,故被列为耐腐蚀性金属.铜合金则比纯铜具有更高的耐腐蚀性能.

简介：ThemicrostructureandopticalpropertiesofaburiedlayerformedbyO+(200keV,1.8×1018/cm2)andN+(180keV,4×1017/cm2)co-implantationandannealedat1200℃for2hhavebeeninvestigatedbyAugerelectron,IRabsorptionandreflectionspectroscopicmeasurements.TheresultsshowthattheburiedlayerconsistsofsilicondioxideandSiOx（x<2）andthenitrogensegregatestothewingsoftheburiedlayerwhereitformsanoxynitride.BydetailtheoreticalanalysisandcomputersimulationoftheIRreflectioninterferencespectrum,therefractiveindexprofilesoftheburiedlayerwereobtained.

简介：本文概述了含有Sn^2+盐、合金成份金属可溶性盐、酸、络合剂和还原剂等组成的Sn合金化学镀液，可以获得附着性、耐蚀性和平滑致密性优良的无Pb和Sn合金镀层，适用于PCB等电子部品的化学镀。

简介：压力容器是内部或外部承受气体或液体压力、并对安全性有较高要求的密封容器。随着化工和石化工业的发展,新工作介质的出现,对压力容器材质在耐压、耐介质腐蚀方面提出了更高的要求。铝合金就是近年来发展比较迅速的容器材料。由于铝的固有物理特性导致焊接铝及铝合金时比较容易出现焊接缺陷,这就给焊接铝合金压力容器提出了更高的技术要求。

简介：Aco-designschemeofevent-triggeredsamplingmechanismandactivefaulttolerantcontrol(FTC)isdeveloped.Firstly,afaultdiagnosisobserverisdesignedtoestimateboththefaultandthestatesimultaneouslybyusingtheevent-triggeredsampledoutput.SomeH∞constraintsbetweentheestimationerrorsandtheevent-triggeredsamplingmechanismareestablishedtoensuretheestimationaccuracy.Then,basedontheconstraintsandtheobtainedfaultinformation,anevent-triggereddetectorandastaticfaulttolerantcontrollerareco-designedtoguaranteethestabilityofthefaultysystemandtoreducethesensorcommunicationcost.Furthermore,theproblemoftheeventdetectoranddynamicFTCco-designisalsoinvestigated.Simulationresultsofanunstablebatchreactorarefinallyprovidedtoillustratetheeffectivenessoftheproposedmethod.

简介：Classifyingthetextureofgranulesin2Dimageshasarousedmanifoldresearchatten-tionforitstechnicalchallengesinimageprocessingareas.ThisletterpresentsanaggregatetextureidentificationapproachbyjointlyusingGrayLevelCo-occurrenceProbability(GLCP)andBPneuralnetworktechniques.First,upto8GLCP-associatedtexturefeatureparametersaredefinedandcomputed,andtheseconsequentparametersnextserveastheinputsfeedingtotheBPneuralnetworktocalculatethesimilaritytoanyofgivenaggregatetexturetype.Afinitenumberofaggregateimagesof3kinds,witheachcontainingspecifictypeofmineralparticles,areputtotheidentificationtest,experimentallyprovingthefeasibilityandrobustnessoftheproposedmethod.

简介：所有纤维基于Er~(3+)：Yb~(3+)共同做在1550nm操作的两倍穿着的光纤激光器被表明。由使用9m渴望Er~(3+)：Yb~(3+)共同做纤维(EYDF)著名计算机生产厂商他获得媒介，并且当波长过滤，用一双纤维布拉格栅栏，产量激光的线宽象0一样狭窄。2nm和产量力量是超过6mW。在它的排放前的激光的荧光灯的效果也被学习。并且它被发现Er~(3+)：Yb~(3+)共同做双clad光纤激光器也在1080nm附近为Yb~(3+)转变展出高获得。

简介：摘要强化型铝合金在室温下具有良好的力学性能，近年来随着制造技术的不断进步，强化型铝合金在工业领域中的运用越来越广泛，对其的焊接也成为研究重点。电子束焊具有穿透能力强、焊缝深宽比大、热影响区以及焊接变形小等优点，适合于高铝合金的焊接。本文对6mm厚的强化型铝合金在电子束焊不同工艺参数下所获接头进行力学性能测试、金相组织观察，结合接头的拉伸性能、冲击性能以及金相组织，研究电子束焊接工艺参数变化对焊接接头质量的影响，达到优化电子束焊接工艺的目的，从而获得具有优良力学性能的焊接接头，进而满足实际工程结构对力学性能的高要求。