简介:EmployingafiberFabry-Perot(FFP)interferometerhasbeenconsideredasatrianglenotchfiltertodemodulatethewavelengthoffiberBragggrating(FBG)sensor.Thesingleparameterofstrainhasbeendemodulated,andthecross-sensitivityinfluenceoftemperaturehasbeeneliminated.Theprincipleofthismethodissimpleandeasytobeimplemented,andhasbeenusedtodesigna30tfibergratingweightbridgesuccessfully.Themaximaltemperaturedrifterroroftheweightbridgeis4με,whichmeansthatthefullscaleerroris8‰.Theresultrevealsthattheaccuracyishighenoughtobeusedinmeasurement.
简介:有一个复杂系数的一个微波photonic槽口过滤器基于混合的四个波浪(FWM)被建议并且示威。二根单个频率的激光横梁的FWM效果发生在里面高度非线性的纤维(HNLF),和多波长光信号被产生并且过去常产生微波photonic过滤器(MPF)的多龙头。复杂系数被使用Fourier域产生光处理器(FD-OP)到控制光搬运人和阶段调整边带的振幅和阶段。结果证明这个过滤器能被控制FD-OP从通带过滤器改变到槽口过滤器。槽口过滤器的中心频率能连续地从5.853GHz被调节到29.311GHz与免费光谱11.729GHz的范围(FSR)。当阶段被调节时,频率反应的形状保持未改变。
简介:Anewvariablestep-sizealgorithmforasecond-orderlatticeformstructureadaptiveinfiniteimpulseresponse(IIR)notchfiltertodetectionandestimationfrequencyofsinusoidsinGaussiannoisesisproposed.Utilizingleastsquarekurtosisofoutputsignalsasacostfunction,thenewgradient-basedalgorithmtoupdatefrequencyoftheadaptiveIIRnotchfilterandthenewvariablestep-sizealgorithmaregiven.ThecomputersimulationresultsshowthattheproposedalgorithmhasbetterabilityinsuppressingcoloredGaussiannoisesandbetteraccuracyinestimatingparametersatlowSNRthanpreviousalgorithms.
简介:UsingTime-VaryingAR(TVAR)modelandadaptivenotchfilterisanewmethodforthenon-stationaryjammersuppressioninDirectSequenceSpreadSpectrum(DSSS).TheperformanceofTVARmodelforInstantaneousFrequency(IF)estimationwillbeaffectedbysomefactorssuchasbasisfunctions.Focusingonthisproblem,theoptimalbasisfunctionofTVARmodelfortheIFestimationoftheLFMsignalisobtainedinthispaper.Besidesthedepthandwidthofnotching,thephasepropertiesofnotchfilteraffecttheSignal-to-Interferenceplus-NoiseRatio(SINR)ofcorrelationoutputtothenarrowbandjammersuppressioninDSSS,inresponsetotheproblemtheclosedsolutionofcorrelationoutputSINRimprovementhasbeenderivedwhenasinglefrequencyjammerpassesthroughdirectIIRnotchfilter,anditsperformancehasbeencomparedwiththoseoffivecoefficientFIRfilters.Later,anovelmethodforLFMjammersuppressionbasedonFourierbasisTVARmodelanddirectIIRnotchfilterisproposed.Thesimulationresultsshowtheeffectivenessoftheproposedmethod.
简介:Theopticalparametersforthreesamplesofintrinsic,dopedSianddopedMg(AlxGa1-x)yIn1-yPpreparedbytheMOCVDonGaAssubstrateweremeasuredbyusingellipsometryandwerecalculatedbythetwo-layerabsorptionfilmmodel.Theresultsobtainedwerediscussed.Thegrownratesandthicknessofoxidiclayerontheintrinsic(AlxGa1-x)yIn1-yPsurfaceexposedintheatmospherewerestudied.Alineardependenceofoxidiclayerthicknessonthetimewasobtained.
简介:RamanscatteringspectroscopyisappliedtoinvestigatethephononmodesinGaxIn1-xP(x=0.52)and(AlxGa1-x)0.51In0.49P(x=0.29)alloys.Two-modebehaviorinGaxIn1-xPandthree-modebehaviorin(AlxGa1-x)0.51In0.49Pareobserved.InorderedGaxIn1-xP,weclearlydistinguishtheTO1(GaP-like)modeandthesplittingofLO1(GaP-like)andLO2(InP-like)modes,whichisbelievedtobetheresultofsuperlatticeeffectofordering,andtheLO1+LO2mode,whichisobservedforthefirsttime.Inadditiontotheb/aratio,it'sfoundthattherelativeintensityoftheFLAandtheLO1+LO2modesalsocorrespondstothedegreeoforder.TheTO1andthesplittingofLO1andLO2devotetogethertothereductionofthe'valleydepth'.In(AlxGa1-x)0.51In0.49P,thedoublingofFLAisobserved.DuetotheinfluenceofAlcomposition,theGaP-likeLOmodebecomesashoulderoftheInP-likeLOmode.TheunresolvedRamanspectraindicatetheexistenceoforderedstructurein(AlxGa1-x)0.51In0.49Palloys.
简介:Basedonthewhiteningpropertyofwavelettransformationfor1/fnoise,thispaperaddressestheproblemofdetectingdeterministicsignalsinthepresenceof1/ffractalnoise.Thetransferfunctionofwhiteningfilterisprovidedaswellastheconditionforwhitening.ThereceiverstructurebasedonKarhunen-Loeveexpansionandthedecisionrulearealsogiven.Finallyperformanceofthedetectorisanalyzed.
简介:Zinchasbeendiffusedinton-typeInxGa1-xAs,InPandGaAsinclosedam-poules,andtheexperimentaldataforInxGa1-xAsrarelyreportedpreviouslyhavebeenob-tained,TheoreticallythelinearrelationsipbetweenlogarithmicdiffusioncoefficientlnDandthecompositionxhasbeendemonstrated,whichisingoodagreementwiththeexperimentalresults.ThecalculateddiffusionjunctiondepthforInGaAsbasedonthediffusionmodelinwhichD^∝c^2isassumedalsoagreeswellwiththatoftheexperment,Finallytheoveralldiffusiontimeinamultiayerheterostructurewasapproximatedast=(∑√-ti)^2.
简介:本文叙述了660MW中间再热机组强制循环汽包炉的炉本体采用盐酸清洗、采用磷酸和多聚磷酸盐进行漂洗钝化的清洗工艺方法.其特点在于:为减缓金属腐蚀,必需严格控制清洗工艺配方.通过缓蚀剂对比小型试验探索出:在酸洗配方和水冲洗过程中,添加适量的异抗坏血酸钠还原剂可以抑制三价铁离子对金属的腐蚀,并可避免因水冲洗时间过长而产生二次锈蚀.该工艺实际应用后效果良好,金属腐蚀速率及腐蚀总量均显著小于(DL/T794-2001)所规定的标准.该工艺还探索出:在酸洗和酸洗后的冲洗水中添加异抗坏血酸钠后,能够有效抑制三价铁离子的腐蚀危害,并减少二次锈蚀的产生.