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

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

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

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：DVS最新推出的Pronto2K2和ProntoHD.2硬盘录像机．使Pronto2K和ProntoHD模块产品系列得到进一步完善。这两款新产品应用了DVS新开发的专用视频板卡，采用软件处理相应的传输延迟和误差．具备全自动传输一致的独特性能。

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：2003年，中国IT服务市场规模呈大幅上升趋势，IT服务正成为IT产业中一个强势增长的市场。特别是随着我国企业信息化的逐步深入，信息化应用和解决方案将会掀起新一轮发展热潮，并将与电子政务一同为IT服务商提供巨大商机。

简介：2004年，宽带市场发展的主要动力来源于固网运营商的推动和市场需求的拉动。宽频娱乐、游戏将是宽带消费的一大热点，娱乐与体育竞技类的服务也是今年宽带内容消费的一大方向。

简介：Linearcomplexityandk-errorlinearcomplexityofthestreamcipheraretwoimportantstandardstoscaletherandomicityofkeystreams.Forthe2n-periodicperiodicbinarysequencewithlinearcomplexity2n1andk=2,3,thenumberofsequenceswithgivenk-errorlinearcomplexityandtheexpectedk-errorlinearcomplexityareprovided.Moreover,theproportionofthesequenceswhosek-errorlinearcomplexityisbiggerthantheexpectedvalueisanalyzed.

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：这份报纸描述一个新方法与高反射率，宽思考带宽和高laserinduced损坏阀值设计一面激光镜子。镜子被HfO2/TiO2/SiO2的三材料高基于电场和所有电介质激光的温度地分发特征构造反射镜。TiO2/SiO2栈充当高反射镜(HR)并且拓宽思考带宽，当HfO2/SiO2栈被用于增加激光抵抗时。有34层的HfO2/TiO2/SiO2激光镜子被一篇小说制作遥远的血浆劈啪作响免职。为新镜子的零损坏可能性的损坏阀值直到39.6J/cm2(1064nm，12ns)。镜子的可能的激光损坏机制被讨论。

简介：borophosphate眼镜的作文上的白光的颜色点的依赖与铕(Eu)和铽(Tb)共同做以稀土元素离子的原子价变化被调查了。在下面紫外(紫外)刺激，白光被观察从在为Eu2+的425nm的4f65d4f7乐队转变排放的联合，5D07FJ(J=1，2)在593nm的线排放和为Eu3+的611nm，并且在为Tb3+的545nm的5D47F5乐队转变排放。由改变玻璃作文，结果的排放颜色能高效地被调节。最后，有委员会的优化的白光国际deIEclairage(CIE)坐标(0.3382，0.2763)并且在5010K的相互关联颜色温度(CCT)被完成。

简介：Inthispaper,awavelengthdivisionmultiplexing(WDM)transmissionsystemderivedfromthecoherentopticalorthogonalfrequencydivisionmultiplexing(CO-OFDM)withpolarizationdivisionmultiplexing(PDM)and16-orderquadratureamplitudemodulation(QAM)isstudied.Asimulationof80-channelWDMtransmissionsystemwithdatarateof200Gbit/sisbuilt,andthetransmissionperformanceofthesystemisanalyzed.ThesimulationresultsshowthatthesystemQvalueoftheWDMchannelsat16Tbit/swithaspectralefficiencyof7.14bit/s/Hzispotentiallyover10.0dBforalonghaultransmissionupto1800kminastandardsingle-modefiber.

简介：开源操作系统，开源数据库都将在未来成为主流。在互联网迅速发展的年代，安全软件将是最重要和最有前途的软件之一。