简介：Basedonthetheoryofthepassivehydrogenmaser,alongwiththetechnologyoffrequencymodulationandmodulationtransferspectroscopy,thetheoreticalexpressionofthesinglefrequencymodulationforthepassivehydrogenmaserandthefunctionofthecavityandHlineerrorsignalsseparationarederived,whicharebasicallycoincidentwiththeexperiment.Theabsorptionanddispersionspectrumcurveswithdifferentresonancewidthsshowthatthecavityandhydrogentransitionserveasdiscriminators,andthetwoerrorsignalscanbeseparated.Throughthecalculationsofthetwoerrorsignalsinthepassivehydrogenmaser,itanalyzesthetraditionalmethodofthetwoerrorsignalsseparation,andthendescribesanewimprovedmethodforthepassivehydrogenservoloopsconsistingintheuseofasinglemodulationfrequencyandfrequencydiscrimination.Anullinteractionofthetwoerrorsignalsforthenewselectionofthephasesettingisdeducedtheoreticallyandvalidatedbythesimulation.Thepreliminaryexperimentalresultconfirmsthefeasibilityofthisnewapproach,whichcanreducetheinfluencefromthecavityfrequencyvarietyonthecrystaloscillatorandcontributesignificantlytothelongtermperformanceofthepassivehydrogenmaser.

简介：Octave-spanningfrequencycombgenerationinmicroresonatorsispromising,butstrongspectrallossescausedbymaterialabsorptionandmodecouplingbetweentwopolarizationsormodefamiliescanbedetrimental.Weexaminetheimpactofthespectrallossandproposerobustcombgenerationwithalossofeven300dB/cm.CavitynonlineardynamicsshowthataphasechangeassociatedwithspectrallossescanfacilitatephasematchingandKerrcombgeneration.Giventhisuniquecapability,weproposeanovelarchitectureofon-chipspectroscopysystems.

简介：Wepresentamethodtogenerateafrequency-doubledmicrowavesignalbyemployingacoupling-modulatedringresonator.CriticalcouplingisachievedwhentheresonatorintrinsiclossisperfectlybalancedbytheexternalcouplingenabledbyaMach–Zehnderinterferometercoupler.Thehighsuppressionofthecarrierleadstoacleantwo-toneopticalsignalwiththefrequencyintervaltwotimeslargerthanthatoftheinputmicrowavefrequency.Thebeatingofthetwo-tonesignalataphotodiodegeneratesthefrequencyupconvertedmicrowavesignal.Atheoreticalmodelisestablishedtoanalyzethemodulationprocessandthemicrowavesignalgeneration.Experimentalresultsshowthattheelectricalharmonicsuppressionratioisaround~20dB(29dB)foraninputmicrowavesignalwith5dBm(10dBm)power.

简介：Thetraditionalsuper-resolutiondirectionfindingmethodsbasedonsparserecoveryneedtodividetheestimationspaceintoseveraldiscreteanglegrids,whichwillbringthefinalresultsomeerror.Tothisproblem,anovelmethodforwidebandsignalsbysparserecoveryinthefrequencydomainisproposed.Theoptimizationfunctionsarefoundandsolvedbythereceiveddataateveryfrequency,onthisbasis,thesparsesupportsetisobtained,thenthedirectionofarrival(DOA)isacquiredbyintegratingtheinformationofallfrequencybins,andtheinitialsignalcanalsoberecovered.Thismethodavoidstheerrorcausedbysparserecoverymethodsbasedongriddivision,andthedegreeoffreedomisalsoexpandedbyarraytransformation,especiallyithasapreferableperformanceunderthecircumstancesofasmallnumberofsnapshotsandalowsignaltonoiseratio(SNR).

简介：在有卡住大头针的边界条件的非局部的nanobeams的postbuckling配置附近的非线性的免费颤动是调查的经分解，认为从中间飞机的拉长并且特别地产生的几何非线性是一个纵的磁场的效果。当应用轴的力量是小的时，nanobeam是稳定的，它的免费颤动在直平衡位置附近。当轴的力量变得大并且在某个批评价值(批评轴的力量)以外，然而，积极或否定的重要平衡配置发生，免费颤动在弄弯的配置附近。当为弄弯的nanobeam它包含立方、二次的非线性时，为在弄弯前的nanobeam的管理方程展出立方的非线性。基于非线性的管理方程，postbuckling配置的近似分析解决方案以应用轴的力量被评估，证明磁场参数在批评轴的力量，弄弯的排水量和nanobeam系统的线性频率上有大效果。更有趣地，当它能是比在postbuckling政体的情况中的线性的低的时，非线性的频率被发现通常比在prebuckling政体的情况中的线性频率高。非线性的频率能被磁场，与中间飞机的拉长联系的非线性的系数，和起始的颤动振幅显著地影响。

简介：Anopposite-chirpedfrequency-domainopticalparametricamplification（OC-FOPA）designisdemonstratedandnumericallyverified.Thisschemecombinesbothanultrabroadseedinggenerationandthesubsequenteffectiveamplificationinonesingleopticalparametricamplificationstage.Basedonaslightlyasymmetrical4-fopticalsystem,thespectralcontentsofbothpumpandsignalwavesarespectrallydispersedwithoppositespatialchirps,tobroadentheinitialidlerseeding.Viaaproperlydesignedfan-outperiodicallypoledLiNbO3chip,nearlyperfectquasiphasematchingcanberealizedacrossthefullspectrum,wherebyeachindividualspectralpairpreciselymapstoitsrequiredgratingperiod.Full-dimensionalsimulationsbasedoncommercial110fs（FWHM）nearinfrared（near-IR）lasersat790and1030nmarequantitativelydiscussed,andfew-cyclemid-IRlaserpulses（60fsat3.4μm）plusahighconversionefficiencyexceeding50%aretheoreticallypredicted.Bymeansofahigh-powerpumpsource,theOC-FOPAschemecanbealsoappliedtodirectlyproducehigh-intensitycarrier-envelope-phase-stabilizedmid-IRidlerpulses.

简介：在有一致频率分布的一个频率加权的Kuramoto模型的同步被学习。我们阴谋分叉图并且识别asymptotic协调状态。数字模拟证明系统在两个经历二一阶的转变前面、向后的方向。除了小锁阶段的状态，新奇nonstationary协调状态，即，一个重要的站波浪状态被观察并且描绘。处于这个状态，因为他们将处于平常的站波浪状态，在协调的簇内的振荡器不是锁频率的。相反，他们的平均频率被锁到一个常数。到重要的站波浪状态的来自支离破碎的状态的批评联合力量能被执行线性稳定性分析获得。理论结果被数字模拟支持。

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

简介：

简介：Forearthquakedisastermitigation,weusehistoricalrecordsandmorecompleteintensityinvestigationdatafrom1500to2015toanalyzeandestimatetheseismicintensityandfrequencyoftheearthquake-proneareasinYunnan.WedigitizedintensityobservationsanddividedtheYunnanregionintocellsizeof0.2°x0.2°tocalculatetheseismicintensity-frequencyrelationshipforeachcell.CombinedwitharepeatedcycleofintensityofonehundredyearsandpopulationeconomicsdatainYunnan,weanalyzefutureareasofconcern.Theresultscanprovideareferenceforearthquakehazardousareazoning.Thismethodisbasedonhistoricalearthquakedata,reducingasmuchaspossiblethevarioushypothesesfortheassessment,andthuscanconciselyreflectthedifferentintensityfrequencydistributionsoftheregion.

简介：Thevibrationalfrequencyanalysisoffiniteelastictubefilledwithcompressibleviscousfluidhasreceivedplentyofattentioninrecentyears.Toapplyfrequencyanalysistodefectdetectionforexample,itisnecessarytoinvestigatethevibrationalbehaviorunderappropriateboundaryconditions.Inthispaper,wepresentadetailedtheoreticalstudyofthethreedimensionalmodalanalysisofcompressiblefluidwithinanelasticcylinder.Thedispersionequationsofflexural,torsionalandlongitudinalmodesarederivedbyelastodynamictheoryandtheunsteadyStokesequation.ThesymbolicsoftwareMathematicaisusedinordertofindthecoupledvibrationfrequencies.Thedispersionequationisdeducedandanalyticallysolved.Thefiniteelementresultsarecomparedwiththepresentmethodforvalidationandanacceptablematchbetweenthemareobtained.

简介：Manypatientswithsensorineuralhearinglosshaveaprecipitoushigh-frequencylosswithrelativelygoodthresholdsinthelowfrequencies.Thispresentpaperbrieflyintroducesandcomparesthebasicprinciplesoffourtypesoffrequencyloweringalgorithmswithemphasisonnonlinearfrequencycompression(NLFC).AreviewoftheeffectsoftheNLFCalgorithmonspeechandmusicperceptionandsoundqualityappraisalisthenprovided.Forvowelperception,itseemsthatthebenefitsprovidedbyNLFCarelimited,whichareprobablyrelatedtotheparametersettingsofthecompression.Forconsonantperception,severalstudieshaveshownthatNLFCprovidesimprovedperceptionofhighfrequencyconsonantssuchas/s/and/z/.However,afewotherstudieshavedemonstratednegativeresultsinconsonantperception.Intermsofsentencerecognition,persistentuseofNLFCmightprovideimprovedperformance.Comparedtotheconventionalprocessing,NLFCdoesnotalterthespeechsoundqualityappraisalandmusicperceptionaslongasthecompressionsettingisnottooaggressive.Inthesubsequentsection,therelevantfactorswithregardtoNLFCsettings,time-courseofacclimatization,listenercharacteristics,andperceptualtasksarediscussed.AlthoughtheliteratureshowsmixedresultsontheperceptualefficacyofNLFC,thistechniqueimprovedcertainaspectsofspeechunderstandingincertainhearing-impairedlisteners.LittleresearchisavailableonspeechperceptionoutcomesinlanguagesotherthanEnglish.MoreclinicaldataareneededtoverifytheperceptualefficacyofNLFCinpatientswithprecipitoushigh-frequencyhearingloss.Suchknowledgewillhelpguideclinicalrehabilitationofthosepatients.

简介：Wereportthefirstobservation,tothebestofourknowledge,ofsum-frequencygenerationinon-chiplithiumniobatemicrodiskresonators.Thesum-frequencysignalinthe780nmband,distinctinwavelengthfromsecondharmonicsignals,wasobtainedinlithiumniobatemicroresonatorsunderthepumpoftwoindividual1550nmbandlasers.Thesum-frequencyconversionefficiencywasmeasuredtobe1.4×10-7mW-1.Thedependenceoftheintensitiesofthenonlinearsignalsonthetotalpumppowerandthewavelengthofonepumplaserwasinvestigatedwhilefixingthewavelengthoftheother.Thisworkpavesthewayforapplicationsofon-chiplithiumniobatemicrodiskresonatorsrangingfrominfraredsingle-photondetectiontoinfraredspectroscopy.

简介：AkindofcircularringhighfrequencywidebandunderwateracoustictransducerisdevelopedbyusingtheLowQvalueandbroadbandcharacteristicsofthepiezoelectricitycompositematerial,andthedualmodecouplingisusedtobroadenthebandwidthofthetransducerbydoubleringstackingalongtheaxialdirection.Throughtheoreticalanalysisandsimulationcalculation,thegeometricdimensionsofthesensitivecomponentsaredetermined.Thepiezoelectriccompositeringsareprocessedandthenthestacksensitiveelementcanbemadebystackingtwopiezoelectriccompositeringswiththesameouterdiameteranddifferentthicknessinaxialdirectionbycuttingpiezoelectricceramicsfillingtheflexiblepolymer-coatingelectrode.Finally,thetransducercanbemadebypouringwaterproofsound-permeablelayer.Theperformancesoftransducerhavealsobeentestedinthewaterandthetestresultsshowthattheresonantfrequencyis410kHz,themaximumtransmitvoltageresponseis150dB,the-3dBbandwidthcanreaches60kHz,thehorizontaldirectivity(-5dB)is360°,andtheverticaldirectivity(-3dB)is20°.Itisalsoshownthatthebandwidthofthetransducercanbeenlargedremarkablybyusingthemethodofstackingtwodifferentthicknesspiezoelectriccompositeringsalongtheaxialdirection,andthehorizontalomnidirectionalemissionofacousticwavecanberealized

简介：

简介：Backconversionisanintrinsicphenomenoninnonlinearfrequencydown-conversionprocesses.However,thephysicalreasonforitsoccurrenceisnotwellunderstood.Here,wetheoreticallyrevealthatbackconversionistheresultofaπ-phasejumpassociatedwiththedepletionofoneinteractingwave.Bysuppressingtheidlerphasejumpthroughadeliberatecrystalabsorption,thebackconversioncanbeinhabited,thusenhancingtheconversionefficiencyfromthepumptothesignal.TheresultspresentedinthisLetterwillfurthertheunderstandingofnonlinearparametricprocessesandpavethewaytowardthedesignofhighlyefficientdown-conversionsystems.

简介：我们表明电的敲击笔记分析和一个连续波浪(cw)锁在3THz(100m)附近射出的兆兆赫量串联激光(QCL)的收音机频率(RF)注射。在免费的跑，QCL的敲击笔记频率与增加开车电流显示出180MHz的移动。敲击笔记，调整反应，拉的注射，和兆兆赫排放光谱在不同当前的政体的特征我，II，和III被调查。结果证明在我关上到激光阀值的当前的政体，我们在洞双程票频率获得RF调整的更狭窄的敲击笔记和扁平的反应。拉的效果并且光谱调整大小在当前的政体验证那我锁住的RF注射是有效的更多和一个柔韧的工具调制模式数字和兆兆赫QCL的模式频率。

简介：在这研究，我们基于一份日报在1961-2014期间为中国的大陆在高温度的事件(HTE)探索了空间模式和时间的趋势--494个车站和nonparametric趋势察觉方法的最大的surface-air-temperature数据集。与35湩a的三阀值

简介：

简介：Dual-pumpedmicroring-resonator-basedopticalfrequencycombs(OFCs)andtheirtemporalcharacteristicsarenumericallyinvestigatedandexperimentallyexplored.ThecalculationresultsobtainedbysolvingthedrivenanddampednonlinearSchr?dingerequationindicatethatanultralowcoupledpumppowerisrequiredtoexcitetheprimarycombmodesthroughanon-degeneratefour-wave-mixing(FWM)processand,whenthepumppowerisboosted,boththecombmodeintensitiesandspectralbandwidthsincrease.Atlowpumppowers,thefieldintensityprofileexhibitsacosinevariationmannerwithfrequencyequaltotheseparationofthetwopumps,whilearollTuringpatternisformedresultingfromtheincreasedcombmodeintensitiesandspectralbandwidthsathighpumppowers.Meanwhile,wefoundthatthepowerdifferencebetweenthetwopumpfieldscanbetransferredtothenewlygeneratedcombmodes,whicharelocatedonbothsidesofthepumpmodes,throughacascadedFWMprocess.Experimentally,thedual-pumpedOFCswererealizedbycouplingtwoself-oscillatingpumpfieldsintoamicroringresonator.ThenumericallycalculatedcombspectrumisverifiedbygeneratinganOFCwith2.0THzmodespacingover160nmbandwidth.Inaddition,theformationofarollTuringpatternathighpumppowersisinferredfromthemeasuredautocorrelationtraceofa10freespectralrange(FSR)OFC.Theexperimentalobservationsaccordwellwiththenumericalpredictions.Duetotheirlargeandtunablemodespacing,robustness,andflexibility,theproposeddual-pumpedOFCscouldfindpotentialapplicationsinawiderangeoffields,includingarbitraryopticalwaveformgeneration,high-capacityopticalcommunications,andsignal-processingsystems.