简介：Theparametricapproachtodesignofhullformwasstudiedinthiswork,whichprovidesthemeansforquickgenerationandvariationofhullformforthehydrodynamicoptimizationofhullform.

简介：Basedonestablishednumericalmethodsandhydrodynamicperformancetestingfacilities,CFDtechniqueareappliedtoimprovethedesignoftheimplantableaxialflowbloodpumpandtheflowanalysis.(1)Applyingbrushlessmachinemagnetsteel,reducingitsthicknesswhileincreasingthelength,theflowchannel'scross-sectionisincreased,withnospaceconnectionbetweenthelargeandthesmallrotators,andwithaconetransitionsegmentfromthebearingtotheprincipalaxis,theflowismadesmoother.Therotatingspeedisloweredby1000rpm-1200rpmunderthesameflowrateandpressurehead,andthusthehemolysiscanbeavoided.(2)Differentoutletstatorguidingvanesareselectedforthesamebloodpumpforanalysesofhydrodynamicperformancesandflowfields.Anexcellentdesignnotonlycanregulatetherotatingflowfieldintoanaxialone,reducethecirculationlossandimprovethepumpefficiency,butalsocanavoidbackflow,vortexandsecondaryflowatthepumpoutlet,andthusthethrombuscanbeprevented.(3)Thecalflivetestsshowthatsomeresidualclotsexistattheinnerwalloftheoutletconnectionbends,whichareanalyzedandexplainedbyCFDtechniquesandthecorrespondingimprovementsareproposed.AllresultsareverifiedbyhydrodynamicperformancetestsandPIVflowfieldtests,andconsistentconclusionsareobtained.

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简介：Inphysicalmodeltestsforhighlyreflectivestructures,oneoftenencountersaproblemofmultiplereflectionsbetweenthereflectivestructuresandthewavemaker.Absorbingwavemakerscancancelthere-reflectivewavesbyadjustingthepaddlemotion.Inthispaper,weproposeamethodtodesignthecontrollerofthe2-Dabsorbingwavemakersysteminthewaveflume.Basedonthefirst-orderwavemakertheory,afrequencydomainabsorptiontransferfunctionisderived.Itstimerealizationcanbeobtainedbydesigninganinfiniteimpulseresponse(IIR)digitalfilter,whichisexpectedtoapproximatetheabsorptiontransferfunctionintheleastsquaressense.AcommonlyusedapproachtodeterminetheparametersoftheIIRfilterisapplyingtheTaylorexpansiontolinearizethefilterformulationandsolvingthelinearleast-squaresproblem.However,theresultisnotoptimalbecausethelinearizationchangestheoriginalobjectivefunction.Toimprovetheapproximationperformance,weproposeaniterativereweightedleast-squares(IRLS)algorithmanddemonstratethatwiththefiltersdesignedbythisalgorithm,theapproximationerrorscanbereduced.Physicalexperimentsarecarriedoutwiththedesignedcontroller.Theresultsshowthatthesystemperformswellforbothregularandirregularwaves.