简介：Techniquesofartificially-triggeredlightninghaveprovidedasignificantlyusefulmeanstodirectlymeasurevariousphysicalparametersoflightningdischargeandtoconductresearchonprotectionmethodsoflightningelectromagneticpulses.Inthisstudy,usingcapacitiveandresistivedividers,currentprobesandopticalfibertransmissiondevices,wemeasuredandanalyzedtheinducedovervoltageontheoverheadtransmissionlineandtheovercurrentthroughSurgeProtectiveDevices(SPD)whenalightningdischargewasartificiallytriggerednearbyonAugust12,2008atConghuaFieldLightningExperimentSite.Thetriggeredlightningdischargecontainedaninitialcurrentstageandeightreturnstrokeswhosepeakcurrentsrangedfrom6.6kAto26.4kA.WefoundthatovercurrentsthroughSPDwereinducedonthepowerlinebothduringtheinitialcontinuouscurrentstageandthereturnstrokeprocesses.Duringthereturnstrokes,theresidualvoltageandthecurrentthroughtheSPDlasteduptothems(millisecond)range,andtheovercurrentsexhibitedameanwaveformupto22/69μswithapeakvalueoflessthan2kA.Basedontheobserveddata,simplecalculationsshowthatthecorrespondingsingledischargeenergywasmuchgreaterthanthevaluesofthehighvoltagepulsegeneratorscommonlyusedintheexperimentsregulatedforSPD.TheSPDdischargecurrentpeakwasnotsynchronoustothatoftheresidualvoltagewiththeformerobviouslylaggingbehindthelatter.TheSPDdischargecurrentpeakwaswellcorrelatedwiththetriggeredlightningcurrentpeakandthewave-frontcurrentgradient.ThelongdurationoftheSPDcurrentisoneofthemajorreasonswhytheSPDwasdamagedevenwithabignominaldischargecurrent.
简介：TheelectrondensityrecordedonboardtheDEMETERsatellitewasanalyzedtosearchforpossibleanomaliesbeforeearthquakesbothinspaceandtime.Todistinguishpre-earthquakeanomaliesfromtheotheranomaliesrelatedtogeomagneticactivity,datawerefilteredusingtheK_pindex.Theanalysisisbasedonthecomparisonofdatarecordedcloselytoearthquakesinspaceandtimeandpastdataforthesamearea.InanalyzingdataaroundthetimeandlocationofthePu'erandWenchuanearthquakes,obviousanomaliesinelectrondensitywerefoundclosetotheepicenters,andsomeremarkabledisturbancesweredetectedbeforetheearthquakesoccurred.Theresultswerefinallycomparedwiththoseofpreviousworksthatusedthesamedatabutemployeddifferentanalysismethods.Goodagreementwasfoundwhichsuggeststhattheseanomalieshaveacloserelationtotheearthquakepreparation.
简介：Anewscreen-spotimagingmethodbasedonopticalmeasurementisproposed,whichisapplicabletotheclose-rangemeasurementofaircraft'sthree-dimensional(3D)attitudeparameters.Lasertrackerisusedtofinishtheglobalcalibrationsofthehigh-speedcamerasandthefixedscreensontestsite,aswellastoestablishmedia-coordinate-framesamongvariouscoordinatesystems.Thelasercooperationobjectmountedontheaircraftsurfaceprojectslaserbeamsonthescreensandthehigh-speedcamerassyn-chronouslyrecordthelight-spots'positionchangingwithaircraftattitude.Therecordedimagesequencesareusedtocomputetheaircraftattitudeparameters.Basedonthematrixanalysis,theerrorsourcesofthemeasurementaccuracyareanalyzed,andthemaximumrelativeerrorofthismathematicalmodelisestimated.Theexperimentalresultshowsthatthismethodeffectivelymakesthechangeofaircraftpositiondistinguishable,andtheerrorofthismethodisnomorethan3′whiletherotationanglesofthreeaxesarewithinacertainrange.
简介：Influencesofthescatteringphasefunctionsonspatiallyresolveddiffusereflectancefromahomogenoussemi-infinitemediumclosetosourcearestudiedwithMonteCarlosimulation.Itisshownthattheinfluencesofopticalparametershigherthanthesecondorderonthediffusereflectancearequiteweakintheregionfrom0.3toseveraltransportmeanfreepatheswhenHenyey-Greensteinphasefunctionoracombinedphasefunctionoftwoparametersareused.ButthisinfluencemaybesubstantialifthedoubleHenyey-Greensteinfunctionisusedtodescribethescatteringpropertyoftissue.
简介：Q:InJiangsuPavilionattheExpoShanghai,wherecanwefindthesignsofLianyungang?A:TnebigscreensintheJiangsuPavilionarethelargestLEDscreengroupusedathome.HereyoucanappreciatethesceneswhicharepeculiartoJiangsu.BesidesSunYat-senMausoleum,SutongGrandBridgeandRiversideEconomicBelt,Lianyungang'smarkinglandscapesincluding
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