简介:ThestatisticalpropertiesofthemodeconvertedSVwavespecklesinthebackscatteringspacewerestudiedasultrasonicPwaveswereincidentonastronglyscatteringinterface.BasedontheFrensel-Huygenstheoryandthecorrelationprinciple,theRayleighdistributionoftheSVwavespeckleamplitudeandtheformulaforcalculatingtheaveragelateralsizeoftheSVwavespeckleswereobtained.Besides,theprobabilitydensityfunctionofthenormalizedintensityoftheSVwavespecklesreceivedbyatransversewaveprobewithanapertureofsomesizewasdeduced.Theprobabilitydensityfunctionwasrelatedtotheaveragenumberofthespecklesreceivedbytheprobe.TwotransversewaveprobeswithaperturesindifferentsizewereemployedtomeasurethesoundintensityoftheSVwavespecklesintheexperiment.Aftertheexperimentaldataofthespeckleintensitywereanalyzedstatistically,itwasshownthattheexperimentalresultswereingoodagreementwiththetheoreticalones.Thus,thepresentedtheoreticalconclusionswereprovedtobecorrect.
简介:针对10种不同坡角的凸起地形,采用基于透射边界的有限元-有限差分计算方法,研究了局部凸起在SV波斜入射时,地震动峰值加速度放大倍数和反应谱谱比随入射角度的变化规律。结果表明:(1)地震波以一定的角度斜入射时,地表大部分观测点的峰值加速度放大倍数大于垂直入射的情况;(2)在计算模型宽高比一定的情况下,最不利入射角度与坡角有一定关系,且地表最不利位置随坡角增大由凸起台地边缘向中心移动;(3)入射角度对凸起地形地震反应谱特性的影响十分显著,不但影响谱比的幅值,也影响谱比曲线的形状,斜入射时各关键节点大部分周期点的谱比值大于垂直入射,入射角度对反应谱中的高频成分影响较为显著,而对长周期成分影响不大。
简介:捷豹特别车辆运营(SVO)部门最近在古德伍德速度节上发布了有史以来最强悍、最灵巧的捷豹公路车——捷豹XESVProject8,它采用全轮驱动系统,搭载5.0升机械增压V8发动机,最大功率为600马力,极速为320公里/小时.这是SVO为收藏家推出的第二款车,前一款是2014年的F-TYPEProject7,专为满足驾驭激情而设计,限量生产300辆.