简介：Weconductedalong-termmonitoringexperimentontheLutuanxiluBridgelocatedinChangpingDistrictofBeijing,employingourrecentlydevelopedreal-timebridgemonitoringsystembasedontheGuralpCMG-6TDbroadbandseismometer.Weidentifiedthemodalparameterswiththestochasticsubspaceidentification(SSI)algorithm,andcontinuouslymonitoredthetemporalvelocityvariationwithcodawaveinterferometry.Theresultsshowthat:(1)thehighlysensitiveGuralpCMG-6TDbroadbandseismometer,whichrecordsthethree-componentvibrationsignalwithinbroadfrequencyrange,iswellsuitedforlong-termbridgehealthmonitoring.(2)Withthecontinuousvibrationsignalfromambientexcitation,thestochasticsubspacealgorithmcanrobustlyidentifythelow-ordermodalparametersandthecodawaveinterferometrycanaccuratelymonitorthetinyvelocityvariation.(3)Theelasticmodulusofbridgematerialschangessignificantlyassociatedwithvaryingtemperature,leadingtodiurnalvelocityvariationwithamplitudeofapproximately1%.Thevelocityvariationshowsstrongnegativecorrelationwithtemperaturefluctuation.Meanwhile,themodalfrequenciesremainquitestable,suggestingthatthevelocityvariationmaybeamoresensitivequantitativedamageindex.(4)Whilethemodalfrequenciesreflecttheintegratedhealthstatusofthebridge,thevelocityvariationcanbeutilizedtomonitorthelocalelasticmodulus.Therefore,itiscrucialforbridgehealthmonitoringtocontinuouslymonitorthetwokeydamageindexesunderambientexcitation.

简介：WereportanenhancementcavityforfemtosecondTi:sapphirelaserattherepetitionrateof170MHz.Anenhancementfactorof24isobtainedwhentheinjectingpulseshaveanaveragepowerof1Wandapulsedurationof80fs.ByplacingaBBOcrystalatthefocusofthecavity,weobtaina392-mWintracavitydoubled-frequencylaser,correspondingtoaconversionefficiencyof43%.Theoutputpowerhasalong-termstabilitywitharootmeansquare(RMS)of0.036%.

简介：时间频率电磁(TFEM)方法联合发出声音，时间域发出声音形成一个全面系统的频率域以便选择不同频率并且根据要探索的客观深度导致波浪是可能的。在处理期间，不仅抵抗力而且极化信息能被提供因此我们能学习抵抗力以及同时预言含有石油的特征。时间域抵抗力信息被pseudo-2D抵抗力倒置获得，频率领域IP信息用海甘蓝海甘蓝模型被获得。在西方的中国的一些成功的应用证明它在一个掩冲断层地区，深火的岩石调查，和烃预言提供唯一的结果。

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简介：宣传在的瑞利波浪的散特征一成层的媒介被一个时间频率分析方法分析，光滑的Pseudo-WignerVille分发(RSPWVD)的重新分配。理论模拟和实验为同类的一半空间和二分层的一半空间被实现。在试验性的结果获得的不同频率范围的组速度分散曲线都相应于在他们的表面排水量振幅的主导的模式，这被显示。多模式瑞利波浪的如此的modeidentification在inversing被要求中等参数。

简介：Weproposeanovelphotonictechniqueformicrowavefrequencymeasurementbasedontransversalmicrowavefilterswithhighresolution.Twoparallelmicrowavefilterswithsineandcosinefrequencyresponsesareobtainedbycrossgainmodulationinasinglesemiconductoropticalamplifier,whichintroducestwodifferentfrequencyresponsestoachieveanamplitudecomparisonfunction.Wealsodemonstrateaproof-of-conceptexperiment.Themeasurementerrorislessthan±0.04GHzforthefirstbandrangeof0–3.45GHzandlessthan±0.03GHzforthesecondbandrangeof3.45–5.8GHz.Ourschemeisfoundtobecapableofbeingextendedforlargerfrequencyrangemeasurementsusingashorterfiberlength.

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简介：Thedischargeoperationregimeofpulsemodulatedatmosphericradiofrequency(RF)glowdischargeinheliumisinvestigatedonthedutycycleandfrequencyofmodulationpulses.Thecharacteristicsofradiofrequencydischargeburstintermsofbreakdownvoltage,alpha(α)-gamma(γ)modetransitionvoltageandcurrentaredemonstratedbythedischargecurrentvoltagecharacteristics.TheminimumbreakdownvoltageofRFdischargeburstwasobtainedatthedutycycleof20%andfrequencyof400kHz,respectively.Theα-γmodetransitionofRFdischargeburstoccursathighervoltageandcurrentbyreducingthedutycycleandelevatingthemodulationfrequencybeforetheRFdischargeburstevolvingintotheignitionphase,inwhichtheRFdischargeburstcanoperatestablyintheγmode.ItproposesthattheintensityandstabilityofRFdischargeburstcanbeimprovedbymanipulatingthedutycycleandmodulationfrequencyinpulsemodulatedatmosphericRFglowdischarge.

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简介：Earthmediumisnotcompletelyelastic,withitsviscosityresultinginattenuationanddispersionofseismicwaves.Mostviscoelasticnumericalsimulationsarebasedonthefinite-differenceandfinite-elementmethods.Targetedatviscoelasticnumericalmodelingformultilayeredmedia,theconstant-QacousticwaveequationistransformedintothecorrespondingwaveintegralrepresentationwithitsGreen'sfunctionaccountingforviscoelasticcoefficients.Anefficientalternativeforfull-waveformsolutiontotheintegralequationisproposedinthisarticlebyextendingconventionalfrequency-domainboundaryelementmethodstoviscoelasticmedia.Theviscoelasticboundaryelementmethodenjoysadistinctcharacteristicoftheexplicituseofboundarycontinuityconditionsofdisplacementandtraction,leadingtoasemi-analyticalsolutionwithsufficientaccuracyforsimulatingtheviscoelasticeffectacrossirregularinterfaces.NumericalexperimentstostudytheviscoelasticabsorptionofdifferentQvaluesdemonstratetheaccuracyandapplicabilityofthemethod.

简介：Inatmosphericradio-frequency(rf)discharges,theplasmaparameters,suchaselectrondensity,sheaththicknessandsheathvoltage,arenoteasytobeprobedexperimentally,whiletheelectricalcharacteristics,suchasimpedance,resistanceandreactance,arerelativelyconvenienttobemeasured.Inthispaperwepresentedasimpletheoreticalmodelderivedfromthefluiddescriptionofgeneratedplasmaswithoutconsideringthecircuitmodel,toinvestigatetherelationshipbetweentheplasmaimpedanceandplasmaparameters.Byintroducingarelaxationfrequency,theplasmaimpedancecouldbepredictedbyformulaspresentedinthisstudy,andthemeanelectrondensityandsheaththicknesscanalsobecalculatedfromthemeasuredorsimulatedimpedanceandreactance,respectively.

简介：Modulatingboththeclockfrequencyandsupplyvoltageofthenetwork-on-chip(NoC)duringruntimecanreducethepowerconsumptionandheatflux,butwillleadtotheincreaseofthelatencyofNoC.Itisnecessarytofindatradeoffbetweenpowerconsumptionandcommunicationlatency.Soweproposeananalyticallatencymodelwhichcanshowustherelationshipofthem.TheproposedmodeltoanalyzelatencyisbasedontheM/G/1queuingmodel,whichissuitablefordynamicfrequencyscaling.Theexperimentresultsshowthattheaccuracyofthismodelismorethan90%.

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简介：Wedemonstratedstablemidinfrared(MIR)opticalfrequencycombatthe3.0μmregionwithdifferencefrequencygenerationpumpedbyahighpower,Er-doped,ultrashortpulsefiberlasersystem.Asolitonmode-locked161MHzhighrepetitionratefiberlaserusingasinglewallcarbonnanotubewasfabricated.TheoutputpulsewasamplifiedinanEr-dopedsinglemodefiberamplifier,anda1.1–2.2μmwidebandsupercontinuum(SC)withanaveragepowerof205mWwasgeneratedinhighlynonlinearfiber.ThespectrogramofthegeneratedSCwasexaminedbothexperimentallyandnumerically.ThegeneratedSCwasfocusedintoanonlinearcrystal,andstablegenerationofMIRcombaroundthe3μmwavelengthregionwasrealized.

简介：Thefeaturesofunsteadyflowsuchaspressurevariationandfluctuationinalargehydraulicturbineusuallyleadtotheinstabilityofoperation.Thisarticlereportstherecentinsiteinvestigationconcerningthecharacteristicfrequenciesinpressurefluctuation,shafttorsionaloscillationandstructuralvibrationofaprototype700MWFrancisturbineunit.Theinvestigationwascarriedoutforawideloadrangeof200MW-700MWintheconditionofwaterhead57m-90m.Anextensiveanalysisofbothtime-historyandfrequencydataoftheseunsteadyhydraulicbehaviourswasconducted.Itwasobservedthatthepressurefluctuationinadrafttubeisstrongerthanthatinupstreamflowpassage.Thelowfrequencywithaboutonethirdofrotationfrequencyisdominativeforthepressurefluctuationinpartloadrange.Alsotheunsteadyfeaturesofvibrationofheadcoverandtorsionaloscillationofshaftexhibitedthesimilarfeatures.Numericalanalysisshowedthatthevibrationandoscillationarecausedbyvortexropeinthedrafttube.Inaddition,astrongvibrationwithspecialcharacteristicfrequencywasobservedfortheheadcoverinmiddleloadrange.Thepressurefluctuationinthedrafttubewiththesamefrequencywasalsorecorded.Becausethisspecialvibrationhasappearedinthedesignednormalrunningcondition,itshouldbeavoidedbycarefullyallocatingpowerloadinthefutureoperation.

简介：Thespectrumvariancem0,peakfrequencyω0andpeaknessfactorpareexpressedintermsofnondimensionalfetchanddurationbymakinguseofrelationswhicharederivedthroughcomparingandanalyzingexistingempiricalformulasforthegrowthofsignificantwaveheightandperiod.ThemainfeaturesofspectrumgrowthasspecifiedbytheseparametersagreewiththoseoftheJONS-WAPexperiments.Forgivenwindspeedandfetch,thehighfrequencypartsbeyondthepeaksofshallowwaterspectraalmostcoincidewiththatofthecorrespondingdeepwaterspectrum,whereasthelowfrequencypartsdifferappreciably.ThemethoddevelopedinthispaperpredictssmallersignificantwaveheightaswellassmallerwaveperiodforshallowwaterspectraincontrasttothetheoreticalresultofKitaigorodskiiefal,inwhichthepeakfrequency,andconsequentlythesignificantwaveperiod,remainsbasicallyunchangedfordifferentwaterdepths.Spectraarefurtherreducedtoaforminwhichonlysignificantwaveh

简介：我们在北伊朗的多山的森林里根据包含的山腰材料(土壤或岩石)和山腰坡度的类型调查了邻近小量的道路的树看台的损坏的分发和频率。80个阴谋的一个总数系统地并且随机被取样记录损坏的树(弯曲，压碎并且伤害)由在道路的边的山腰坡度和材料的班。树在岩石斜坡伤害并且压碎比在有黏土的混合的山腰显著地大(p?45%是比在有斜坡坡度的山腰上更经常的2，8.5和2.3次<15%为分别地弯曲，压碎并且伤害。类型和最经常的损坏改变的损坏分发是树伤害(p?

简介：Thispaperpresentsanequalizationalgorithmforcontinuousphasemodulation(CPM)overfrequency-selectivechannels.Aspecifictrainingsequenceisfirstembeddedineachdatapacket.Byrecursiveleast-squares(RLS)estimation,thechannelinformationparameterscanbeacquired,andafractionallyspacedequalizerperformsjointdecodingandequalization.Simulationresultsshowthattheproposedalgorithmcanacquirethechannelinformationparametersrapidlyandaccurately,andthatthefractionallyspacedequalizercaneliminatetheintersymbolinterference(ISI)effectively,andisnotsensitivetotiminginaccuracy,sothisalgorithmcanbeexploitedfordemodulationsysteminburstmode.

简介：在这份报纸，三存在来源光谱为地面运动的随机的有限差错的建模的模型被考察。这三个模型被用来从一个垂直差错和平均数在一个地点计算远地的收到的精力光谱在Northridge地震的15个车站上的比率，然后比较。从比较，一项必要措施被观察维持subfault尺寸的远地的收到的精力独立人士并且避免overestimation长时期光谱水平。二改进被做到三个模型之一(即，模型基于动态角落频率)如下：(i)计算subfault角落频率的一个新方法被建议，在subfault角落频率基于从取决于的全部差错和增长的全部的地震时刻计算的基本价值是坚定的的地方，地震时刻分到subfault；并且(ii)从每subfault的放射精力的差别被考虑进可伸缩的因素。改进模型也与通过远地的收到的精力和平均数的未耕过的模型相比光谱比率。比较证明改进模型允许收到的精力比未耕过的模型更独立于subfault尺寸，并且减少overestimation度长时期光谱振幅。

简介：在在灰尘天气的半球和它的可能的角色的低频率摆动在2002在诺思中国上袭击事件作为案例研究被分析。结果证明阿留申群岛之土人Low在3060天的摆动上在南半球与环极涡旋被连接，与趋于加深可能对尘暴事件的产生有用的阿留申群岛之土人Low的弱环极涡旋。在这后面的可能的机制是吝啬的经向环流的内部半球的相互作用，与在东亚上的主要可变性。在在上面的水平对流层的南半球的高纬度的带的吝啬的偏午可以带北半球的，它然后在北半球影响地方性环流。因此，低频率摆动电视连接是在在诺思中国上在南半球发行量和灰尘事件之间联合的一个可能的连接。然而，内部低频率摆动的年变化是不清楚的。