简介：Waveguideinvariantiswidelyusedinunderwatertargetpassiveranging.Inshallowwaterwithuniformsoundspeedprofile,thevalueofwaveguideinvariantisapproximatelyaconstant,whileinshallowwaterwiththermocline,itvariesinawiderange.Thewaveguideinvariantdistributionsandstriationsinthesetwoconditionsareanalyzedrespectively.Onthebasisofwavenumberdifferencebetweenreflectedmodesandrefractedmodes,awavenumber-frequencydomainfilteringtechniqueisproposedtoseparatethetwogroupsofmodes.Therequiredrelationshipbetweenarrayelementspace,totalarraylengthandtargetazimuthforeffectiveapplicationisdiscussed.Finally,thesimulationresultsindicatethatinshallowwaterwithathermocline,refractedmodescanbeeffectivelyfilteredoutusingthewavenumber-frequencydomainfilteringtechniqueandthetarget’srangeisestimatedaccurately.

简介：Thetime-domainElectroMagnetic(EM)scatteringbyburiedobjectsindispersivemediaiscalculatedwithFD-TDmethod.TheFD-TDformulainDebyedispersivemedia(boththecomplexpermeabilityandthecomplexpermittivityaredescribedbyDebyeequations)arededuced,andtheabsorbingboundaryconditionisgiven.ThevalidityofFD-TDmethodinlossymediaisverifiedthroughcomparingtheFD-TD’sresultsandtheotherones.Thepropagationoftransientpulsesindispersivemediaisstudiedindetail.Thescatteringpulsesandthewiggletracesfortypicalburiedobjectsaregiven.

简介：大赌才能大赢——如今这个说法在商界非常流行，不仅有很多人信奉此论，而且有不少人将其付诸实践，以期一“赌”翻生，破茧成蝶。

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