834
Table1.ConditionalprobabilitytablewithbeliefstructuresinFMEA
___________________________________________________________________________________________
RulesAntecedentattributesAllisionrisk
_________________________________________________________________________________________
Theprobabilityof ConsequencechanceofallisionPoor Fair Average`Good Excellent
allision(L)severity(C)riskbedetected(P)
___________________________________________________________________________________________
1 VerylowNegligibleUnlikely0.33 0.000 0.00 0.00 0.67
2 VerylowNegligibleReasonablyunlikely 0.00 0.333 0.00 0.00 0.67
3 VerylowNegligiblelikely0.00 0.000 0.33 0.00 0.67
4 VerylowNegligibleReasonablylikely 0.00 0.000 0.00 0.33 0.67
5 VerylowNegligibleDefinite0.00 0.000 0.00 0.00
1.00
… ………… … ………
… ………… … ………
121 VeryfrequentCatastrophicUnlikely1.00 0.00 0.00 0.00 0.00
122 VeryfrequentCatastrophicReasonablyunlikely 0.67 0.33 0.00 0.00 0.00
123 VeryfrequentCatastrophiclikely0.67 0.00 0.33 0.00 0.00
124 VeryfrequentCatastrophicReasonablylikely 0.67 0.00 0.00 0.33 0.00
125 VeryfrequentCatastrophicDefinite0.67 0.00 0.00 0.00 0.33
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Table2.Expertjudgementsunderdifferentvesselcategories
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Vesselcategories ExpertsNo. Judgementresults
LCP
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FishingvesselE10.4,0.6,0.8,0.9 0.1,0.15,0.2,0.45 0.2,0.3,0.45,0.55
E20.6,0.7,0.75 0.1,0.2,0.50.2,0.3,0.5
E30.80.50.15
ServicevesselE10.75,0.8,0.85,0.950.25,0.4,0.5,0.55 0.35,0.45,0.65,0.85
E20.8,0.9,10.05,0.2,0.40.25,0.55,0.75
E30.90.150.45
TankerE10,0.05,0.15,0.2 0.65,0.7,0.85,0.95 0.65,0.7,0.85,0.95
E20,0.15,0.20.45,0.8,0.90.5,0.7,0.95
E30.050.950.85
Generalcargovessel E10,0.05,0.15,0.2 0.45,0.6,0.7,0.95 0.6,0.8,0.9,1
E20,0.25,0.30.5,0.75,0.90.7,0.75,0.95
E30.10.60.7
Passengervessel E10.25,0.45,0.5,0.550.65,0.75,0.8,0.95 0.65,0.7,0.85,0.95
E20.05,0.25,0.45 0.55,0.6,0.850.4,0.65,0.7
E30.20.750.55
___________________________________________________________________________________________
and
5
1
mm
m
SL R PN R
(1)
wheretheSL meansthe safetylevelindex. Ahigher
safety level means low risk of allision, the opposite
resultmeansahighriskofvesselallision.
3 IMPLICATIONANDDISCUSSION
Theaboveintroducedmethodsareusedtoinvestigate
thevesselallisionriskneartheOWFunderdifferent
categories.
According to the categories given in AIS
records,vesselsagroupedas‘thefishingvessel’,‘the
servicevessel’,‘thetanker’,‘thegeneralcargovessel’
and ‘the passenger vessel’. A group of three experts
from different background are invited to provide a
subjective evaluation of the allision risk of every
vessel type.
To test the transformation technology
introducedinsection2.1,theexpertsareaskedtogive
their judgement under a different format. The
judgementresultsetispresentedasTable2.
By using the fuzzy transformation technology,
judgementresultscanbetransformedintotheCPTfor
L,PandC,
whichgivenasTable3,Table4andTable
5:
Table3.CPTfornodeʹprobabilityofallisionʹ
____________________________________________
StatesofL Vesselcategories
Fishing Service Tanker GeneralPassenger
____________________________________________
Verylow 0.0000 0.0000 1.0000 1.0000 0.2500
Low0.0000 0.0000 0.0000 0.0000 0.4722
Average 0.1111 0.0000 0.0000 0.0000 0.2778
Frequent 0.7222 0.0000 0.0000 0.0000 0.0000
Veryfrequent0.1667 1.0000 0.0000 0.0000 0.0000
____________________________________________
Table4.CPTfornode‘consequenceseverity’.
____________________________________________
StatesofC Vesselcategories
Fishing Service Tanker GeneralPassenger
____________________________________________
Negligible 0.2778 0.3833 0.0000 0.0000 0.0000
Marginal 0.4444 0.3667 0.0000 0.0000 0.0000
Moderate 0.2778 0.2500 0.0556 0.2391 0.0000
Critical 0.0000 0.0000 0.5000 0.7174 0.7833
Catastrophic 0.0000 0.0000 0.4444 0.0435 0.2167
____________________________________________
Table5.CPTfornode‘chanceofallisionriskundetected’.
____________________________________________
StatesofP Vesselcategories
Fishing Service Tanker GeneralPassenger
____________________________________________
Unlikely0.2143 0.0000 0.0000 0.0000 0.0000
Reasonably 0.6429 0.1151 0.0000 0.0000 0.0000
unlikely
Likely 0.1429 0.5992 0.0000 0.0000 0.5833
Reasonably 0.0000 0.2857 0.5833 0.4444 0.3056
likely
Definite 0.0000 0.0000 0.4167 0.5556 0.1111
____________________________________________