SAMSUDIN AHMAD Faculty of Geoinformationand Real Estate ...
Transcript of SAMSUDIN AHMAD Faculty of Geoinformationand Real Estate ...
SAMSUDINAHMADFacultyofGeoinformation andRealEstate
Universiti Teknologi Malaysia@Mail:[email protected]
History
• Late1950s– ProgramEvaluationandReviewTechnique(PERT)
• U.S.Navy,Booz‐AllenHamilton,andLockeheedAircraft
• Probabilisticactivitydurations– CriticalPathMethod(CPM)
• DupontDeNemoursInc.• Deterministicactivitydurations
TheLanguageofPERT/CPM
• Activity– taskorsetoftasks– useresources
• Event– stateresultingfromcompletionofoneormoreactivities
– consumenoresourcesortime– predecessoractivitiesmustbecompleted
TheLanguageofPERT/CPMcontinued
• Milestones– eventsthatmarksignificantprogress
• Network– diagramofnodesandarcs– usedtoillustratetechnologicalrelationships
• Path– seriesofconnectedactivitiesbetweentwoevents
TheLanguageofPERT/CPMconcluded
• CriticalPath– setofactivitiesonapaththatifdelayedwilldelaycompletionofproject
• CriticalTime– timerequiredtocompleteallactivitiesonthecriticalpath
SampleProblemforFindingtheCriticalPathandCriticalTime
Activity Predecessor Duration
a -- 5 daysb -- 4c a 3d a 4e a 6f b, c 4g d 5h d, e 6i f 6j g, h 4
CalculatingProbabilisticActivityTimes• ThreeTimeEstimates
– pessimistic(a)– mostlikely(m)– optimistic(b)
95PercentLevel
• Taskwillbea orlower5percentofthetime
• Taskwillbeb orgreater5percentofthetime
3.3)( ab
90PercentLevel
• Taskwillbea orlower10percentofthetime
• Taskwillbeb orgreater10percentofthetime
6.2)( ab
TraditionalStatisticsVersusSimulation• Similarities
– mustenumeratealternatepaths
• Differences– simulationdoesnotrequireassumptionofpathindependence
PrecedenceDiagramming
Finish‐to‐startlinkage
Start‐to‐startlinkage
Finish‐to‐finishlinkage
Start‐to‐finishlinkage
OtherMethods
• GraphicalEvaluationandReviewTechnique(GERT)– combinesflowgraphs,probabilisticnetworks,anddecisiontrees
– allowsloopsbacktoearliereventsandprobabilisticbranching