简介:Wavediffractionoftwoconcentricporouscylinderswithvaryingporositywasstudiedbyusingananalyticalmethodbasedoneigenfunctionmatching.Thefluiddomainaroundthecylindersisdividedintothreesub-domainsandineachsub-domainaneigenfunctionexpansionofthevelocitypotentialisobtainedbysatisfyingtheLaplaceequation,theboundaryconditionsonthefreesurfaceandontheseabed.Theunknowncoefficientsofeigenfunctionexpansionsaredeterminedbyboundaryconditionsontheporoushulls.Inthepaper,theboundaryconditionsarebasedupontheassumptionthattheflowintheporousmediumisgovernedbyDarcy’slaw.Twoporous-effectparametersappliedontwoporouscylindersarefunctionsoftheverticalcoordinateinsteadoftheconstant.Waveloadingontheouterandinnercylinderispresentedinthenumericalresults.
简介:研究了烧结温度和保温时间对电流活化烧结Fe-2Cu-1.5Ni-0.5Mo-0.8C混合粉末的影响.结果表明,当位移变化量几乎为零时,延长保温时间或增加烧结温度,烧结体密度仍有增长,且有明显的强化烧结.增加烧结温度比延长保温时间更能有效提高烧结体的密度、硬度和抗弯强度.
简介:文中通过FSA方法,分析构成海事事故的危险因素,提出实际有效的风险控制措施,基于有效性和经济性评估风险控制方案,从而得到最后的选择结果,完成本次基于FSA的秦皇岛港通航安全的研究。