简介：AnewnonparametricprocedureisdevelopedtotesttheexponentialityagainstthestrictNBUCpropertyofalifedistribution.Theexactnulldistributionisderivedbythetheoryofsamplespacings,andtheasymptoticnormalityisalsoestablishedbythelargesampletheoryofL-statistics.Finally,theloweranduppertailedprobabilityoftheexactnulldistributionandsomenumericalsimulationresultsarepresentedaswell.

简介：Assumeanunreliableworkstationperformingjobswitharandomservicetime,namely,itoccasionallybreaksdownbecauseofunexpectedinterruptions.Asaninterruptionreallyoccurs,thestationisinstantaneouslyrepairedandtheuncompletedjobisrestartedagainfromthebeginningtillajobiscompletedwithoutbeinginterrupted.ThetotalservicetimeisshowntobeNBUifandonlyifthetotaltimeittakestofinisheachjobwithinterruptionsisstochasticallylargerthanthatwithoutthem,irrespectiveofwhenandhowthebreakdownsoccur.Asanapplication,anonparametricprocedureisdevelopedtotestforthestrictNBUpropertyoftheservicetime.Finally,somenumericalsimulationsarepresentedaswell.