简介：ConventionalGaborrepresentationanditsextractedfeaturesoftenyieldafairlypoorperformanceinextractingtheinvariancefeaturesofobjects.Toaddressthisissue,aglobalGaborrepresentationmethodforraisedcharacterspressedonlabelisproposedinthispaper,wheretherepresentationonlyrequiresfewsummationsontheconventionalGaborfilterresponses.Featuresarethenextractedfromthesenewrepresentationstoconstructtheinvariantfeatures.ExperimentalresultsclearlyshowthattheobtainedglobalGaborfeaturesprovidegoodperformanceinrotation,translation,andscaleinvariance.Also,theyareinsensitivetoilluminationconditionsandnoisechanges.ItisprovedthatGaborfilterscanbereliablyusedinlow-levelfeatureextractioninimageprocessingandtheglobalGaborfeaturescanbeusedtoconstructrobustinvariantrecognitionsystem.

简介：AraisedpanelmethodbasedonNURBS(Non-UniformRationalB-Splines)forfree-surfaceflowswithforwardspeedispresented.Inthisgeneralizedpanelmethod,NURBSareemployedtorepresentthebodygeometry,disturbedfreesurface,andtoexpresstheunknownsourcestrengthdistribution,onthebodysurfaceandabovethefreesurface.Comparedwithcommonhigher-orderpanelmethods,ithasnoneedofadoptinglocalcoordinates.NURBSmakethegeometryrepresentationofthebodyshapeandthewavepatternmoreprecise.Raisedpanelsabovethefreesurfaceproducelessnumericaldispersionerror,needlessCPUconsumptionandarehelpfulandcombinedwithcollocation-pointshiftingup-stream,cansatisfytheradiationconditionnumerically.ByusingcontinuousanddiscreteFourieranalysis,numericalerrorsofthismethodarediscussedandageneralexpressionfortheerrorsofnumericaldampinganddispersion,includingtheeffectsoftheverticaldistanceofsingularitiestothefreesurface,theorderofsingularitydistributionrepresentedbyB-splinesinpanels,andcollocation-pointshiftingisderived.

简介：Photoniccrystalfibers(PCFs)withasteppedraised-coreprofileandonelayerequallyspacedholesinthecladdingareanalyzed.Usingeffectiveindexmethodandconsideringaraisedsteprefractiveindexdifferencebetweentheindexofthecoreandtheeffectiveindexofthecladding,weimprovethecharacteristicparameterssuchasnumericalapertureandV-parameter,andreduceitsbendinglosstoaboutonetenthofaconventionalPCF.ImplementingsuchastructureinPCFsmaybeonestepforwardtoachievelowlossPCFsforcommunicationapplications.

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