学科分类
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20 个结果
  • 简介:Hydrodynamiccharactersonahorizontal,thin,rigidplatelocatedbeneaththefreesurfacearenumericallyinvestigated.Assumingalinear,time-harmonicpotentialflowandutilizingGreenidentity,thegoverningLaplaceequationcanbesimplifiedintoFredholmintegralequationofthesecondkind.Supposinglinear-orderdiscontinuouselementsalongintersectingverticalboundaries,andbyuseoftheboundaryelementmethod,numericalsolutionaboutsourcestrengthdistributionontheplatecanbechangedintoaseriesofalgebraicequations.The3DGreenfunctionisintroducedtosetuptheintegralequations,andtheGMRESsolverisperformedforsolvingthelargedenselinearsystemofequations.Theadded-mass,dampingforceandexcitingforceareevaluateddirectlyfromtheequations.Itisfoundthattheadded-masscoefficientbecomesnegativeforarangeoffrequencieswhentheplateissufficientlyclosetothefreesurface.

  • 标签: SUBMERGED plate Dreen function Added mass
  • 简介:Thepurposeofthispaperistodevelopafunctionalmethodfordesigningaseriesofsubmergedbreakwatersonpracticaltopography.ThemethodisusedtoverifythefeasibilityandeffectivenessofBraggbreakwatersforcoastalprotectionbyusingfieldtopography.ThefirstpartofthispaperprovidesdefinitionsandproceduresneededinthedesignprocessforapplyingthemechanismofBraggreflection.Next,Braggbreakwatersaredesignedonthebasisofthecross-sectionaltopographyandthenontheplanetopographyoftheMi-Tuocoastbyfollowingtheproposedprocessandprocedure.Numericalmodeling(Hsuetal.,2003;WenandTsai,2008)wasusedasadesignandassessmenttool.Finally,theeffectivenessandfeasibilityofaBraggbreakwaterwasassessedbypracticalcases.BasedonthemechanismofBraggreflection,anoptimumlayoutforaseriesofsubmergedbreakwatersisproposedtoprotecttheMi-Tuocoast.Theresultsindicatethattheproperlayoutofaseriesofsubmergedcreakwaterscanachievetheobjectiveofbeachprotection.

  • 标签: 设计过程 海岸保护 潜堤 布拉格反射 海岸地形 反射机制
  • 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。

  • 标签: 沿海 沙质岸 淹没 水平距离 实验室 海洋结构物
  • 简介:—Theresultsofdesignandexperimentofasubmergedsemi-circularbreakwaterattheYangtzeestuaryshowthatthesubmergedstructurewillbeunsafewhenthegeneralempiricalwaveforceformulaforsemi-circularbreakwaterisusedindesign.Therefore,anewcalculationmethodforthewaveforcesact-ingonasubmergedsemi-circularstructureisgiveninthispaper,inwhichthewaveforceactingonthein-sidecircumferenceofsemi-circulararchisincluded,andthephasemodificationcoefficientinthegeneralempiricalformulaisadjustedaswell.Thenewwaveforcecalculationmethodhasbeenverifiedbythere-sultsofsevenrelatedphysicalmodeltestsandadoptedinthedesignofthesouthesturaryjettyofthefirststageprojectofDeepChannelImprovementProjectoftheYangtzeRiverEstuary,thetotaljettylengthbe-ing17.5km.

  • 标签: SEMI-CIRCULAR BREAKWATER SUBMERGED structure ESTUARY jetty
  • 简介:Thispaperdiscussessomeprevious,andpresentssomenewexperimentalresultsonwavetransmissionoversubmergedbreakwaters.Theobjectiveofthisstudyistoevaluatewavetransmissioncoefficientanddevelopatwo-dimensional(2D)modelasanimprovementtotheexistingwavetransmissioncoefficientmodels.Factorswhichaffectwavetransmissionoversubmergedbreakwatersarediscussedthroughaseriesoflaboratoryexperiments.Basicrecommendationsforevaluationanddesignofsubmergedrubble-monudbreakwatersarepresented.Fromthetestresults,acalculationformulaofwavetransmissioncoefficientisproposed.

  • 标签: 水下碎石防波堤 波传输系数 波损耗 数学模型
  • 简介:Thenumericalinvestigationofregularwavesinteractingwithasubmergedhorizontaltwin-platebreakwaterispresentedinthispaper.Anumericalmodelwithanabsorbingwave-makerisestablishedbasedontheVOFmethod.Thevalidityofthemodelisverifiedbyexperimentalresults.Comparisonsbetweenthenumericalandexperimentalresultsshowthatboththewatersurfaceprofilesandthewave-inducedpressurescanbemodeledaccurately.Wavedeformationoverthebreakwater,waterparticlevelocitiesaroundthebreakwater,andthewave-inducedpressuresonthestructurearenumericallyinvestigated.Thepressureamplitudesofthefundamentalandsecondharmonicsonthemodelsurfaceareexaminedinvariouswaterdepths.Thecomputedandexperimentalresultshaverevealedthatthehigherfrequencycomponentsaregeneratedattheonshoresideofthebreakwater.Furthermore,thecomputedresultsdemonstrateacirculatingflowformedattheonshoresideofthebreakwater.

  • 标签: 数值模拟 相互作用 防波堤 卧式 数学模型 验证实验
  • 简介:由于胭脂波浪的物理机制的复杂性,rogue-wavestructure相互作用问题的理论学习仍然取得很少进步。为常规形状的结构,然而,给理论分析是可能的,如果流氓波浪的一个相对简单的模型被使用。波浪负担,由作为胭脂波浪的一个直觉的基本模型被知道的一个集中的波浪导致了,在沉没半的柱体之上被学习经分解。集中的波浪由高斯信封波浪是近似的,包含流氓波浪的大多数特征的一个理想的模型。衍射速度潜力通过水平力量的流动地,和公式的分离被导出,弯曲时刻被建议。导出的公式适当地被简化,并且对数字结果通过比较验证了。另外,参数的影响集中的沉没深度和波浪例如集中的度,放,彻底地被调查。

  • 标签: 柱体 沉没 负担 理论学习 物理机制 相互作用
  • 简介:Investigatingthewavefieldnearstructuresincoastalandoffshoreengineeringisofincreasingsignificance.Inthepresentstudy,simulationisdoneofthewaveprofileandflowfieldforwavespropagatingoversubmergedbars,usingPLIC-VOF(PiecewiseLinearInterfaceConstruction)totracethefreesurfaceofwaveandfinitedifferencemethodtosolvevertical2DNavier-Stokes(N-S)equations.AcomparisonofthenumericalresultsfortwokindsofsubmergedbarswiththeexperimentalonesshowsthatthePLIC-VOFmodelusedinthisstudyiseffectiveandcancomputethewavefieldprecisely.

  • 标签: PLIC-VOF模型 有限元分析 波浪 环境保护 N-S方程 数值模拟
  • 简介:BasedonthesimulationwiththeOcean-AtmosphereCoupledModelCCSMandOceanModelPOPunderthegreenhousegasemissionscenariooftheIPCCSRESA2(IPCC,2001),andontheearthcrustsubsidenceandglaciermeltingdata,therelativesealevelchangeisobtainedalongthecoastofChinainthe21stcentury.UsingtheSRTMelevationdatathesubmergenceofcoastallowlandiscalculatedundertheextremewaterlevelwitha100-yearreturnperiod.Thetotalfloodingareasare98.3×103and104.9×103km2for2050and2080,respectively.Forthethreeregionsmostvulnerabletoextremesealevelrise,i.e.,thecoastofBohaiBay,theYangtzeRiverDeltatogetherwithneighboringJiangsuProvinceandnorthernZhejiangProvince,andthePearlRiverDelta,thefloodedareasare5.0×103,64.1×103and15.3×103km2in2050and5.2×103,67.8×103and17.2×103km2in2080,respectively.

  • 标签: 海平面上升 中国海岸 沿海地区 淹没区 气候变化 长江三角洲地区
  • 简介:全部的推迟的微粒(TSP)样品沿着Qingdao的海岸在三个地点被收集,中国,在前并且在在2002年3月的主要尘暴期间。为比较,PM_(10)(有空气动力学的直径的微粒物质不到10μm)样品被收集三个地点赎回。词法观察和体积和单个粒子的组合分析被使用扫描与为TSP和PM_(10)的散X光检查系统(SEM/EDX)取样的一个精力装备的电子显微镜学执行。结果证明形态学的不同类型的粒子有类似的形态学的不同元素的作文,而是粒子总是没为非灰尘样品有一样的元素的作文。非灰尘粒子的Themorphology和作文在不同地点是不同的。分数维、球形的粒子为非灰尘样品主要在粗粒级存在,当时在好模式(<10μm)有絮状物,一起结队并且包含外壳的元素的好粒子形成。与非灰尘粒子相比,尘粒以形态学,颗粒大小和作文是更同类的。有andwell分布式的尺寸在灰尘样品统治了的不规则的形状的粒子,包含象Mg那样的外壳的元素,艾尔,Si,Ca,Fe,等等。高硫内容显示了那同类并且多相反应在Qingdao的特定的环境发生在尘粒的表面上。

  • 标签: 气溶胶 颗粒污染物 电子显微镜扫描 灰尘 大气污染
  • 简介:Settlingvelocityisafundamentalparameterinsedimenttransportdynamics.ForuniformPar-ticles,thereareabundantformulasforcalculationoftheirsettlingvelocities.Butinnaturalfields,sedi-mentconsistsofnon-uniformparticles.Theinteractionamongparticlesiscomplexandshouldnotbeneg-lected.Inthispaper,basedontheanalysisofsettlingmechanismofnon-cohesiveandnon-uniformparti-cles,atheoreticalmodeltodescribesettlingmechanismisproposed.Besidessuspensionconcentrationandupwardturbulentflowcausedbyotherparticles,collisionamongparticlesisanothermainfactorinflu-encingsettlingvelocity.Byintroducingthecollisiontheory,equationsoffallvelocitybeforecollision,colli-sionprobability,andfallvelocityaftercollisionareestablished.Finally,aformulausedtocalculatetheset-tlingvelocityofnon-cohesiveparticleswithwidegraingradationispresented,whichagreeswellwiththeexperimentaldata.

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  • 简介:Basedontheanalysisoftropicalcyclone(TC)databaseintheNorthwestPacific(NWP)from1945to2008,wenotonlyextractthetemporalvariationofTCintensityandfrequency,butalsogivetheirspatialdistributionbothintheNWPandintheSouthChinaSea(SCS).TheresultsshowthatthereisanobservationalincreaseofTCactivities,whichmanifestsastheenhancementofthepowerdissipationindex(PDI)andthegrowthofTCfrequency,especiallyfortyphoonsandstrongtyphoons.TheinhomogeneousspatialdistributionsofTCfrequencyandintensityarealsoprovidedbothintheNWPandintheSCS.Forexample,theregionofZhongshaIslandsandDongshaIslandsintheSCS(15°~22°N,115°~120°E),westtothePhilippineIslandsistheplacewithfrequentoccurrenceofstrongtyphoons,amongwhichthewindspeedof7TCsin64yearsexceeds60m/s.

  • 标签: 热带气旋活动 西北太平洋 非平稳 东沙群岛 南海地区 空间分布
  • 简介:Naturalhazardssuchashurricanesmaycauseextensiveeconomiclossesandsocialdisruptionforcivilstructuresandinfrastructuresincoastalareas,implyingtheimportanceofunderstandingtheconstructionperformancesubjectedtohurricanesandassessingthehurricanedamagesproperly.Theintensityandfrequencyofhurricaneshavebeenreportedtochangewithtimeduetothepotentialimpactofclimatechange.Inthispaper,aprobability-basedmodelofhurricanedamageassessmentforcoastalconstructionsisproposedtakingintoaccountthenon-stationarityinhurricaneintensityandfrequency.Thenon-homogeneousPoissonprocessisemployedtomodelthenon-stationarityinhurricaneoccurrencewhilethenon-stationarityinhurricaneintensityisreflectedbythetime-variantstatisticalparameters(e.g.,meanvalueand/orstandarddeviation),withwhichthemeanvalueandvariationofthecumulativehurricanedamageareevaluatedexplicitly.TheMiami-DadeCounty,Florida,USA,ischosentoillustratethehurricanedamageassessmentmethodproposedinthispaper.Theroleofnon-stationarityinhurricaneintensityandoccurrencerateduetoclimatechangeinhurricanedamageisinvestigatedusingsomerepresentativechangingpatternsofhurricaneparameters.

  • 标签: hurricane DAMAGE assessment intensity frequency non-stationarity
  • 简介:AerosolsampleswerecollectedonboardtheresearchvesselXuelongduringtheFifteenthChineseAntarcticResearchExpedition(CHINAREXV)inNovember1998-April1999andtheFirstChineseArcticResearchExpeditioninJuly-September1999.TheareastraversedbytheexpeditionarycruisesincludetheArcticOcean,thewesternNorthPacificOceanandtheeasternIndianOcean,covering75°N-69°Sand75°E-133°W.AerosolsampleswerealsotakenattheChineseZhongshanStationinEastAntarcticaduringtheCHINAREXV.Analysisofthesamplesyieldedconcentrationsofnon-sea-saltsulfateandothersolublechemicalspeciesinthemarineboundarylayer.Thedatasuggestthatthechemicalcompositionofthemarineaerosolsisinfluencedbythreemajorsources:continentalairmasses,primaryoceanicemissions,andsecondarymarineaerosolsoriginatedfromoceanicemissions.Theresultsshowthat,awingtostronganthropogenicsulfuremissionsfromtheAsiancontinent,non-sea-saltsulfateconcentrationsintheNorthernHemisphere(thewesternNorthPacific)marineaerosolaresignificantlyhigherthanthoseintheSouthernHemisphere(theeasternIndianOcean).Aerosolnon-sea-saltsulfateconcentrationsappeartobeinverselycorrelatedwithaerosolnon-sea-saltchloridewhichshowssignificantlynegativevalues,indicatingthelossofchloridebyseasalts,inmostaerosolsamples.SincegaseousHClmaybeinvolvedinchemicalreactionsthatdepleteatmosphericozoneinthemarineboundarylayer(MBL),highlevelsofacidicnon-sea-salt-sulfatereleasedbyhumanactivitiesinthelowandmid-latitudesoftheNorthernHemispheremaybecomeanimportantpotentialcontributortothelossofatmosphericozoneintheMBL.

  • 标签: non-sea-salt SULFATE MARINE BOUNDARY LAYER CHLORIDE
  • 简介:Inthispaper,thecharacteristicsofdifferentformsofmildslopeequationsfornon-linearwaveareanalyzed,andnewnon-lineartheoreticmodelsforwavepropagationarepresented,withnon-lineartermsaddedtothemildslopeequationsfornon-stationarylinearwavesanddissipativeeffectsconsidered.Numericalsimulationmodelsaredevelopedofnon-linearwavepropagationforwatersofmildlyvaryingtopographywithcomplicatedboundary,andtheeffectsarestudiedofdifferentnon-linearcorrectionsoncalculationresultsofextendedmildslopeequations.Systematicalnumericalsimulationtestsshowthatthepresentmodelscaneffectivelyreflectnon-lineareffects.

  • 标签: non-linearity MILD slope equations COMPLICATED BOUNDARY
  • 简介:InthisstudyweassessedthecurrentstatusofcoralreefsalongtheSaudiArabiancoastoftheRedSea.AmongthethreegrowthformsofAcroporidcorals,thebranchingformswerefoundtodominateintheFarassanIslands(44.55%±11.10%cover)followedbytabularformsintheDogaIslands(rangingbetween18%±6.47%and18.30%±9.47%cover).DigitateformswererarelyfoundalongthecoastexceptatMaqna.Amongthefivegrowthformsofnon-Acroporidcorals,weobservedmaximumcoverofbranchingformsintheYanbuoffshorearea(58.89%±15.11%cover)followedbytheJeddahcoast(24.76%±14.04%cover).TheMilleporaspp.,anon-Scleractiniancoral,wasabundantatallthenear-shoresites,suchasJeddah(10.70%±8.21%)andAl-Wajh(9.81%±6.69%).Thelivecoralcover(includingbothScleractinianandnon-Scleractiniancorals)ofSaudiRedSeacoastwasseentobehigherinthenorthandgraduallydecreasetowardsthesouth.PrincipalComponentanalysisshowedthatthecontributionofAcroporidcoralswasgreaterinthesouthernregionthaninthenorthernandmiddleregions,butvice-versainthecaseofnon-Acroporidcorals.Bray-Curtisclusteranalysiscategorizedallthestudysitesintotwomajorclusterswith60%similarity.Amongthem,onecluster-formingsitesfromMaqnatoMasturah(Northernregion)andthesecondonecomprisedthemiddleandsouthernregions(JeddahtoFarassanIslands),andoneoutlierRabigh.

  • 标签: 造礁石珊瑚 沙特阿拉伯 快速评估 海岸 生长形态 红海
  • 简介:OptimalstockingdensitieswereinvestigatedfortheseacucumberApostichopusjaponicusSelenkaunderfeed-supplementandnon-feed-supplementregimesinnetenclosuresfor333d.Substantialweightlossoccurredduringtheaestivationphase(AE).Decreasedgrowthrateswerealsoobservedduringthewinterphase(WT).Incontrast,seacucumbersshowedrapidgrowthduringthespring(SP)andautumn(AU)phases.Feedingregimesconsiderablyinfluencedthegrowthperformance,i.e.,seacucumbersgrewfasterunderfeed-supplementregimethanundernon-feed-supplementregime(P<0.05).Theaveragesurvivalratesofseacucumbersunderfeed-supplementregimewerehigherthanthoseundernon-feed-supplementregimeforboththeautumnphaseandspringphase,butthedifferenceswereonlysignificantforthelatterphase(P<0.05).ThefittedB-Ncurvesshowedthattheoptimalstockingdensities,intermsofnetproduction,were22.3ind.m-2forfeed-supplementregimeand14.1ind.m-2fornon-feed-supplementregime.

  • 标签: 饲料补充 海参 养殖密度 池塘养殖 优化 编制
  • 简介:Seacucumbers,ApostichopusjaponicusSelenka,werefeddietscontainingnon-immunostimulant(basaldiet),0.2%β-glucanand0.02%glycyrrhizininarecirculatorywatersystemfor45days,andsubsequentlychallengedwithVibriosplendidusbyinjectionat1.0×108cfu/seacucumberfor15days.Phagocyticcapacity(PC),intracellularsuperoxideanionproduction(ISAP),ly-sozyme(LSZ)activityandsuperoxidedismutase(SOD)activityinthecoelomicfluidwereanalyzedonthe0th,5th,10thand15thdaysafterinjection.Resultsshowedthatafterthe45-dayfeedingperiod,PC,ISAP,LSZactivityandSODactivityinseacucumbersfedwithdietaryβ-glucanorglycyrrhizinweresignificantlyhigherthaninthosefedwiththebasaldiet.Onthe5thdayafterinfection,alltheimmuneparametersexaminedintheseacucumbersinjectedwithV.splendidusdecreasedinvaluesignificantly.Onthe15thday,PC,ISAPandLSZactivityreturnedtolevelssimilartothoseonthe0thday.Fortheseacucumbersinjectedwithsaline,therewerenosignificantdifferencesinalltheimmuneparametersexaminedandinthecumulativemorbidityduringthe15-daychallengingtrial.AfterinjectingwithV.splendidus,thecumulativemorbidityofseacucumbersfedwiththebasaldietwassignificantlyhigherthanthosefedwithdietaryβ-glucanorglycyrrhizinwhenchallengedwithV.splendiduschallengedseacucumberfedwiththebasaldietwassignificantlyhigherthanthosefedwithdietaryβ-glucanorglycyrrhizin.Therewasnosignificantdifferenceincumulativemorbiditybetweenthedietaryβ-glucanandglycyrrhizintreatmentsovertime.

  • 标签: 基础日粮 非特异性免疫功能 葡聚糖 甘草酸 超氧化物歧化酶活性 海参