基于干涉和φ-otdr复合的分布式光纤振动传感技术的-研究

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1、重庆大学硕士学位论文中文摘要④频率信息对于动态振动测量是一个重要的参数。快速傅里叶变换(FFT)只能适用于平稳和周期性的振动信号的频谱分析。而对于非平稳瞬态信号，如材料撕裂、发动机的振动，FFT算法不能反映瞬态信号的局部频域特性，我们利用经验模式分解(EMD)方法分析非稳态振动信号的时频特性。实验中，我们采用扫频信号(500Hz~1KHz)驱动压电陶瓷管模拟非稳态振动，所得实验结果与扫频信号的频率信息吻合，因此对于φ-OTDR系统来说，EMD算法是一种有效的非稳态信号处理方法。关键词：分布式传感，瑞利散射，干涉，二维边缘检测，经验模态分解，空间分辨率，频率响应II重庆大学硕士学位论文英文摘

2、要ABSTRACTDistributedopticalfibersensingisatechnologyusingopticalfiberasthesensingmedium,andcarriesonremoteandreal-timemonitoringofthetargetalongthesensingfiber.Itiswidelyusedinlong-rangesafetymonitoring(i.e.pipelinemonitoringofnaturalgasandoil)orhealthmonitoringofcivilstructures(i.e.bridgeandhighb

3、uilding).Uptonow,distributedopticalfibervibrationsensingbasedoninterferometryandbackscatteringtechnology(RayleighorBrillouinscattering)aredeeplyresearchedbydomesticandforeignscholars.Thefrequencyresponseofinterferometriesisveryhigh,butthesignaldemodulationmethodneedstobefurthersimplifiedandthespat

4、ialresolutionshouldbeimproved，moreimportantly,interferometriesbaseddistributedvibrationsensingsystemshavenocapabilityofmultiplevibrationpointslocationanddetectionsimultaneously.Ontheotherhand,thefrequencyresponseofvibrationsensingbasedonBrillouinscatteringisrelativelylow.RayleighscatteringbasedOTD

5、Rtechnologyownsthefollowingmerits:highspatialresolution,multi-pointdetectionandsimplesignalprocessing.However,duetotheweakintensityofRayleighbackscatteringlight,averagingmethodisadoptedinsignalprocessingwhichresultsinthefrequencyresponsesharplydecreasing.Therefore,weproposeacompositesensingschemec

6、ombiningtheinterferometryandRayleighbackscatteringtechnologytoachievedistributedvibrationmeasurementwithhighspatialresolutionandhighfrequencyresponsesimultaneously.Themaincontentsofthisthesisareasfollowing:①TheoriesoninterferometriesandRayleighbackscatteringaredescribedbriefly,andthefeasibilityofc

7、ombiningtwotechnologiesisdiscussed.Firstly,accordingtothegenerationmechanismofRayleighbackscatteringlightinopticalfiber,theoperatingprincipleofphase-sensitiveOTDR(φ-OTDR)systemisanalyzedbybuildingthediscretemodel