简介：Thebesthydraulicchannelsectionmakesthemaximumflowcapacityforthesameflowcross-area,andtheminimumcross-areaandwettedperimeterforthesamedischarge.Theconstructioncostcanbereducednearlytotheminimumatthesametime.Thehorizontalbottomparabolicsection(HBPsection)isacompositesection.Itisimportantfordesigntofindthebestcombinationformofthehorizontalbottomandtheparabolicsides.Thispaperstudiesthebesthydraulicsectionanditshydrauliccharacteristics.Theexplicitformulaeareproposedtodeterminethedimensionsandthebestcombinationformofthehorizontalbottomandtheparabolicsides.Theseexplicitformulaeandtheparametersmakeiteasytodesignthechannel.Itisshownthattheratiosofthesurfacewidthtothedepthandthebottomwidthtothedepthareconstantforthebesthydraulicsection.Thecomparisonswiththeclassicparabolic,rectangular,trapezoid,triangular,semi-cubicandhorizontal-bottomedsemi-cubicsectionsshowthattheHBPsectionhasthelargestflowcapacityandtheshortestwettedperimeterforthesameflowarea,andhasthesmallestflowareaforthesamedischarge.ItisindicatedthattheparabolicsidepartsofthebesthydraulicHBPsectionaredifferentfromthoseoftheclassicsection.TheresultsofthebesthydraulicsectionoftheclassicparabolicchannelcannotbeapplieddirectlytotheHBCsection.

简介：BasedonTianetal.'stheoreticalmodelofmicrowavescattering,byusingthewindwavespectrumsuggestedbyFungetal.,numericalresultsofpolarizedback-scatteringwerecalculated.Thequantitativerelationshipsbetweenthecalculatedbackscatteringcross-sectionandtheenvironmentalparameters,suchaswindspeeds,azimuthalanglesandincidenceangles,werestudied.Comparedwiththetraditionaltwo-scalescatteringmodel,theresultsaremuchmorecoincidentwiththeobservationsundertheconditionofmoderateincidenceangles,whichisveryusefultomakeupforthetwo-scalemodel.Tomakethenewcalculationmodeltobeusedconvenientlyinthepractice,itssimplifiedformwasproposed.