简介：Hydrodynamiccharactersonahorizontal,thin,rigidplatelocatedbeneaththefreesurfacearenumericallyinvestigated.Assumingalinear,time-harmonicpotentialflowandutilizingGreenidentity,thegoverningLaplaceequationcanbesimplifiedintoFredholmintegralequationofthesecondkind.Supposinglinear-orderdiscontinuouselementsalongintersectingverticalboundaries,andbyuseoftheboundaryelementmethod,numericalsolutionaboutsourcestrengthdistributionontheplatecanbechangedintoaseriesofalgebraicequations.The3DGreenfunctionisintroducedtosetuptheintegralequations,andtheGMRESsolverisperformedforsolvingthelargedenselinearsystemofequations.Theadded-mass,dampingforceandexcitingforceareevaluateddirectlyfromtheequations.Itisfoundthattheadded-masscoefficientbecomesnegativeforarangeoffrequencieswhentheplateissufficientlyclosetothefreesurface.

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简介：Thebendingrigidityofsubmergedvegetationiscloselyrelatedwithvegetativedragforce.Thisworkaimsatdeterminingtheeffectsofflowconditionsandcharacteristicsofvegetationonthebendingrigidityofsubmergedvegetation.Basedonthedimensionalanalysismethod,thefactorsinfluencingthebendingrigidityofindividualsubmergedvegetationwereanalyzed.Therelationshipbetweentherelativebendingrigidityanditsinfluencingfactorswasinvestigatedbyexperimentalobservation,andarelativebendingrigidityexpressionforsubmergedvegetationwasobtainedbymeansofmultiplelinearregressionmethod.Theresultsshowthatthesubmergedvegetationhasthreestatesunderdifferentinflowconditions,andtheeachcriticalrelativebendingrigidityofindividualsubmergedvegetationwasdeterminedforthedifferentstatesofsubmergedvegetation.

简介：Submergedvegetationhasasignificantimpactonwaterflowvelocity.Currentinvestigationsincludetheimpactthroughaddingdragresistanceandincreasingbottomroughnesscoefficient,whichcannotelucidatethecharactersofrealsubmergedvegetation.Toevaluatetheeffectsofsubmergedvegetationonwatercurrentsatdifferentvelocities,alaboratoryexperimentwasconductedusingthreekindsofvegetations.Theeffectiveheightsofthesevegetationsonvaryingflowvelocitieswereevaluated.AnequationdescribingtherelationshipbetweenthenormalizedresistanceofthesubmergedplantsandtheReynoldsnumberbasedontheplanteffectiveheightwasthenestablishedandusedtocalculatethehydraulicresistanceparametersofsubmergedplantsindifferentstagesofgrowth.

简介：学习的paleoforest遗体在18000m~2的一个范围以内被散布在内部Qianhu海湾的潮汐的地区，福建省。89个古老的树树桩能清楚地在paleoforest遗体被认出。相对，低使碳化树桩取样的10的显微镜的研究毫无疑问显示出四种：Glyptostrobuspensili(Staunt)Kouch，Schima出色Gardn，CinnamomumSchaeffer，和Litsea打。一些样品标明日期的~(14)C产出42560±3的年龄50到>43000一B.P.，相应于晚迟了的更新世。

简介：INTRODUCTIONItisaninterestingresearchareausingureaseinhibitorstocurbureaseactivityinsoil,todecreasetherateofureahydrolysisandtoincreasetherecoveryofureanitrogen(Zhou,1984;Guan,1985).Fewstudieshavebeenconductedontherelationshipbetweentheeffectivenessoftheinhibitorsappliedtoriceandtheenvironmentalconditionsandits

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简介：题目：水下板桩叶片对移动河床的影响研究　　目的：比较板桩叶片和简单的平板叶片在控制河床沉积物再分配时的效率。　　方法：1.在不受当地侵蚀现象影响的接近障碍物和下游区域的直线水道中研究河床的形态；2.使用不同的实验装置测试简单几何形状的平板叶片和复杂形状的603K叶片的性能；3.在不同的叶片迎角和浸没参数下，测试与其面积接近的结构和在远场中的河床形态。　　结论：1.叶片的形状和迎角影响其对河床形态所产生的作用，尤其是对于较大的淹没参数而言；2.平板叶片和板桩叶片对下游河床的重塑作用相似；3.随着迎角的增加，平板叶片将造成更深的冲刷孔。这可能归因于与平板叶片相关的马蹄形涡流增加的侵蚀能力，而板桩叶片的不均匀表面可减轻该涡旋的侵蚀强度。

简介：Aquaticvegetationhasasignificantimpactonwatercurrents.Toevaluatetheeffectsofchangesintheaquaticvegetationonwatercurrentsofdifferentvelocity,a3-Dhydrodynamicmodelwasthendevelopedbytakingintoconsiderationoftheadditionalhydraulicresistanceoftheaquaticplants.TheNavier-StokesequationswerethensolvedusingtheSIMPLEmethodandthek-εturbulencemodel.CalculationsusingtheestablishedmodelswereusedtoforecasttheverticaldistributionofthehorizontalvelocityandhorizontalflowunderthetransmissionconditionsoftheSouth-NorthWaterDiversionintheNansiLake.Andcomparativecalculationfortheflowvelocitywasalsoperformedusingthesimplifiedmethodofassigningahighroughnesscoefficienttothelakebedinthesamearea.Resultssuggestthataddingadditionalhydraulicresistanceoftheaquaticplantsisfeasible.Thecalculationerrorsbetweensimulationresultandthefieldobserveddataaresmallerthan15%,while,thoseerrorsareupto35%iftheinfluenceofaquaticvegetationisdealtwiththesimplifiedmethod.

简介：Thepurposeofthispaperistodevelopafunctionalmethodfordesigningaseriesofsubmergedbreakwatersonpracticaltopography.ThemethodisusedtoverifythefeasibilityandeffectivenessofBraggbreakwatersforcoastalprotectionbyusingfieldtopography.ThefirstpartofthispaperprovidesdefinitionsandproceduresneededinthedesignprocessforapplyingthemechanismofBraggreflection.Next,Braggbreakwatersaredesignedonthebasisofthecross-sectionaltopographyandthenontheplanetopographyoftheMi-Tuocoastbyfollowingtheproposedprocessandprocedure.Numericalmodeling(Hsuetal.,2003;WenandTsai,2008)wasusedasadesignandassessmenttool.Finally,theeffectivenessandfeasibilityofaBraggbreakwaterwasassessedbypracticalcases.BasedonthemechanismofBraggreflection,anoptimumlayoutforaseriesofsubmergedbreakwatersisproposedtoprotecttheMi-Tuocoast.Theresultsindicatethattheproperlayoutofaseriesofsubmergedcreakwaterscanachievetheobjectiveofbeachprotection.

简介：Theproblemsofasolitarywavepassingoverrectangularcylindershavebeenanalysed.Thenumericalsimulationisbasedonthefullnonlineartwo-dimensionalNavier-Stokesequationswhicharesolvedbythefinitedifferencemethod.ThefreesurfaceisdealtwithbytheVolumeofFluidmethod(VOF).ResultsforasolitarywavepassingoverasinglecylinderarecomparedwiththeexperimentaldataofSeabra-Santos,PenouardandTempervilleandbetteragreementisobtainedthanthoseobtainedfromthelongwaveequationbasedonthepotentialflowtheory.Resultsarealsogivenfortwocylinderswithdifferentgaps.

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简介：暴露于波浪的跨岸的沉积运输率为沿海的形态学，象防波堤那样的海洋的结构的设计，突堤，防波提等等，和由于onoff岸沉积交通的沿海的侵蚀和生长的预防是很重要的。在现在的学习，跨岸的沉积运输的实验与1/8，1/10和1/15的起始的沙滩斜坡在一条实验室波浪隧道被执行。由使用常规波浪，不同深海的波浪险峻由一个踏脚板类型波浪生成器产生了，沙滩的几何特征在影响开关岸沉积运输的暴风雨条件和参数下面介绍与d50=0.25的中等直径为沙滩材料被调查，0.32，0.45，0.62和0.80公里。近海酒吧几何特征是从海岸线的水平距离到酒吧开始(Xb)，冠(Xt)，并且(Xs)结束指，从酒吧冠的深度到静止的水水平(ht)，并且酒吧体积(V酒吧)。当时，试验性的结果显示了那深海的险峻(H0/L0)增加，到海滨的网运动增加了。与增加的波浪险峻，移动附此从静止的水拓宽垂直距离的酒吧铺平到酒吧开始(Xb)，冠(Xt)并且结束(Xs)从海岸的点和水平距离排队到酒吧开始，冠和结束的点增加了。它也从试验性的结果被显示出来自开始并且结束点到海岸线的酒吧的水平距离与沙滩斜坡的减少增加了。从这研究获得的试验性的结果与以前的试验性的工作相比并且发现具有象试验性的大小的一样的大小并且跟随期望的基本趋势。

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简介：Theeffectoffullysubmergedbouldersontheflowstructureinchannelshasbeenstudiedbysomeresearchers.However,manynaturalstreamshavebedmaterialwithbouldersthatarenotfullysubmergedunderwater.Inmanynaturalstreams,boulderscoverbetween1%and10%oftheareaofthestreamreach.Theeffectofnon-submergedbouldersonthevelocityprofileandflowcharacteristicsisveryimportantforassessingriverbeddeformation.Theobjectivesofthispaperaretofindthepatternofvelocitydistributionaroundanon-submergedboulderandtocompareitwiththeclassicalstudiesonflowresistanceandReynoldsstressdistributioninopenchannels.Also,byconsideringthevariationintheReynoldsstressdistributionatdifferentlocationsaroundanon-submergedboulder,theeffectofanon-submergedboulderontheestimationofshearvelocityandresistancetoflowhasbeeninvestigated.Resultsindicatesthatinsidethescourholecausedbyanon-submergedboulderinarivervelocitydistributionsareirregular.However,velocitydistributionsareregularoutsidethescourhole.ThepresenceofthebouldercausesaconsiderabledeviationoftheReynoldsshearstressfromtheclassicdistribution,showinganon-specificdistributionwithnegativevalues.TheclassicalmethodsforcalculatingshearvelocityarenotsuitablebecausethesemethodsdonotgivedetailedvelocityandReynoldsstressdistributionsinnaturalriverswithalotofboulders.Thus,theeffectofanon-submergedboulderontheestimationoftheresistancetoflowbyconsideringthevariationsinvelocityandReynoldsstressdistributionsatdifferentlocationsaroundanon-submergedboulderisimportantandneedstobestudiedinanaturalriverinsteadofjustinlaboratoryflumes.ThenegativevaluesinReynoldsstressdistributionaroundaboulderindicatethattheclassicalmethodsareunabletopredictresistancetoflow,andalsoshowstrongturbulenceinsidethescourholewherethecomplexflowconditionspresentambi

简介：—Theresultsofdesignandexperimentofasubmergedsemi-circularbreakwaterattheYangtzeestuaryshowthatthesubmergedstructurewillbeunsafewhenthegeneralempiricalwaveforceformulaforsemi-circularbreakwaterisusedindesign.Therefore,anewcalculationmethodforthewaveforcesact-ingonasubmergedsemi-circularstructureisgiveninthispaper,inwhichthewaveforceactingonthein-sidecircumferenceofsemi-circulararchisincluded,andthephasemodificationcoefficientinthegeneralempiricalformulaisadjustedaswell.Thenewwaveforcecalculationmethodhasbeenverifiedbythere-sultsofsevenrelatedphysicalmodeltestsandadoptedinthedesignofthesouthesturaryjettyofthefirststageprojectofDeepChannelImprovementProjectoftheYangtzeRiverEstuary,thetotaljettylengthbe-ing17.5km.

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简介：有流动上的不同安排密度的纵的酒吧介绍的不同沉没障碍和一个scour洞的形态学的效果在清楚的水条件下面被调查。声学的Dopplervelocimetry(副词)数据被使用阴谋三维的速度和狂暴的轮廓的垂直分布。试验性的结果显示那安排密度(能也代表孔)，结构的材料(灵活或稳固)，并且sidewall效果是影响狂暴的动能和形态学的主要因素搜索洞。为灵活植被，床表面附近的最大的狂暴的动能与安排密度增加了。为一样的结构，深度和scour洞的侧面的扩大的大小也与安排密度增加了。因为偏转和安排密度，灵活植被减少了scour洞的深度。大量scour在结构在灵活植被比作很好那些的固体的在上游、中间的节发现了。多孔的灵活植被的偏转下游地搬运了狂暴的动能，在沉积床附近减少了狂暴的动能，并且增加了酒吧的稳定性。灵活植被酒吧能在正常条件下面保护河岸和一条河的床，使他们成为在河的管理和恢复的一个好其他的图案。

简介：Thispaperdiscussessomeprevious,andpresentssomenewexperimentalresultsonwavetransmissionoversubmergedbreakwaters.Theobjectiveofthisstudyistoevaluatewavetransmissioncoefficientanddevelopatwo-dimensional(2D)modelasanimprovementtotheexistingwavetransmissioncoefficientmodels.Factorswhichaffectwavetransmissionoversubmergedbreakwatersarediscussedthroughaseriesoflaboratoryexperiments.Basicrecommendationsforevaluationanddesignofsubmergedrubble-monudbreakwatersarepresented.Fromthetestresults,acalculationformulaofwavetransmissioncoefficientisproposed.