简介:Theaddedmasscoefficientandthewaterlevelindexformulasforthesame-phaseandanti-phasevibrationofrectangularliquidtanks'bulkheadswerederivedbasedondrymodetheory.Threefluid-structureinteractionnumericalmethodsincludingFluidFEMandFluidBEMwereusedinthiscase.ThecomparisonofnumericalandtheoreticalresultsbythepresentmethodshowsthatANSYS/FluidS0ismorecredible,theNASTRAN/VirtualMassMethodismoresuitableforengineeringcalculationsandresultsofthesame-phasevibrationbythepresentmethodismoreaccurate.
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简介:弄平的粒子水动力学(SPH)是一个Lagrangian无网孔的粒子方法。然而,它内核近似的低精确性当粒子是分布式的时在边界附近混乱或定位是以它的宽应用程序的方法站的一个障碍。采用泰勒系列扩大方法并且解决不可分的方程矩阵,第二个顺序核近似方法能被获得,也就是K2_SPH,它在这份报纸被讨论。这个方法类似于有限粒子方法。与核近似的改进,一些数字技术应该为边界的不同类型被采用,例如一条免费表面边界和稳固的边界,它是为水波浪模拟的K2_SPH的二种关键数字技术。这份报纸给一些涉及由使用K2_SPH承受波浪和sloshing坦克问题的二维的水波浪模拟的数字结果。从模拟结果的比较,K2_SPH方法比标准SPH更可靠。
简介:疲劳裂缝和疲劳损坏是为轮船的重要的期并且近海结构很长时间。在最后十年,与在壳结构和逐渐地大的轮船尺寸的更高张力的钢的介绍,然而,更大的注意应该被给予使问题疲劳。的大多数研究焦点更容易存取轮船的疲劳力量。另外,主要分类社会已经释放了他们的疲劳评价笔记。由于影响疲劳表演的因素的复杂性,然而从货物,不同压力部件的联合,本地结构细节的集中上的压力,工具压力,和腐蚀剂环境装载例如波浪并且迫使,有有改变分类社会的不同说明,从不同疲劳评价方法导致不同结果。这篇论文证实DetNorskeVeritas(DNV)分类笔记使对解释疲劳评价的过程的轮船结构的评价疲劳并且简化了方法。最后,疲劳分析被一艘真实轮船的使用数据执行,结果的可靠性被估计。
简介:S-surfacecontrolhasproventobeaneffectivemeansformotioncontrolofunderwaterautonomousvehicles(AUV).Howevertherearestillproblemsmaintainingsteadyprecisionofcourseduetotheconstantneedtoadjustparameters,especiallywheretherearedisturbingcurrents.Thusanintelligentintegralwasintroducedtoimproveprecision.AnexpertS-surfacecontrolwasdevelopedtotunetheparameterson-line,basedontheexpertsystem,itprovidesS-surfacecontrolaccordingtopracticalexperienceandcontrolknowledge.Topreventcontroloutputover-compensation,afuzzyneuralnetworkwasincludedtoadjusttheproductionrulestotheknowledgebase.ExperimentswereconductedonanAUVsimulationplatform,andtheresultsshowthattheexpertS-surfacecontrollerperformsbetterthananS-surfacecontrollerinenvironmentswithcurrents,producinggoodsteadyprecisionofcourseinarobustway.
简介:Arraycalibrationisimportantinengineeringpractice.Inthispaper,fastcalibrationmethodsforaULA'sgainandphaseerrorsbothinfarandnearfieldsareproposed.Inthefarfield,usingasinglesoundsourcewithoutexactorientation,thismethodhorizontallyrotatesthearrayexactlyonce,performseigenvaluedecompositionforthecovariancematrixofreceiveddata,thencomputesthegainandphaseerroraccordingtotheformulas.Inthenearfield,usingthesamesinglesoundsource,itisnecessarytorotatethearrayhorizontallyatmostthreetimes,buildequationsaccordingtogeometricrelations,thensolvethem.Usingtheformulaproposedinthispaper,sphericalwavesaremodifiedintoplanewaves.Theneigenvaluesdecompositionisperformed.Thesetwocalibrationmethodswereshowntobevalidbysimulationandarefast,accurateandeasytouse.Finally,ananalysisoffactorsinfluencingestimationprecisionisgiven.
简介:Oceanographicsurvey,orothersimilarapplicationsshouldbetheapplicationsofmultipleAUVs.Inthispaper,theskill&simulationbasedhybridcontrolarchitecture(S2BHCA)asthecontroller'sdesignreferencewasproposed.Itisamulti-robotcooperationorientedintelligentcontrolarchitecturebasedonhybridideas.TheS2BHCAattemptstoincorporatethevirtuesofthereactivecontrollerandofthedeliberativecontrollerbyintroducingtheconceptofthe"skill".Theadditionalonlinetasksimulationabilityforcooperationissupported,too.Asanapplication,amultipleAUVcontrolsystemwasdevelopedwiththree"skills"fortheMCMmissionincludingtwodifferentcooperativetasks.Thesimulationandtheseatrialsshowthatsimpletaskexpression,fastreactionandbettercooperationsupportcanbeachievedbyrealizingtheAUVcontrollerbasedontheS2BHCA.
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简介:面对biofilms,不锈钢(SS)展览腐蚀潜力的增加,叫的崇高。在现在的学习,腐蚀潜力(E<潜水艇class=“a-plus-plus”>双SSUNSS32760的corr)行为同时被记录与在里面在Arraial的区域做Cabo的在二的situ水兵biofilm形成,东南的巴西。在Forno港口(一个人为地扰乱的区域)的biofilm被更高相对的许多细菌在白天2点描绘,在白天10上由硅藻(特别Naviculasp)列在后面并且白天18上的dinoflagellates,而没有清楚的趋势在CaboFrio岛(一个没受到干扰的区域)被记录。E的崇高<潜水艇class=“a-plus-plus”>corr价值是地点依赖者。在互补实验室试金,biofilms被移开并且E<潜水艇class=“a-plus-plus”>corr价值处于无菌的条件登记了为随后10天并且在situ结果支持了。理解biofilms和SS相互作用象帮助在这知识填重要差距一样为材料科学和工程决定有重要含意。