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DesignanddevelopVoIPsoftwareonembeddedprocessor
Businessprocessmining:
Anindustrialapplication OriginalResearchArticle
InformationSystems,Volume32,Issue5,July2007,Pages713-732
W.M.P.vanderAalst,H.A.Reijers,A.J.M.M.Weijters,B.F.vanDongen,A.K.AlvesdeMedeiros,M.Song,H.M.W.Verbeek
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ApproximatesolutionfortwostageopennetworkswithMarkov-modulatedqueuesminimizingthestatespaceexplosionproblem OriginalResearchArticle
JournalofComputationalandAppliedMathematics,Volume223,Issue1,1January2009,Pages519-533
OrhanGemikonakli,EnverEver,AltanKocyigit
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Abstract
Analyticalsolutionsfortwo-dimensionalMarkovprocessessufferfromthestatespaceexplosionproblem.Twostagetandemnetworksareeffectivelyusedforanalyticalmodellingofvariouscommunicationandcomputersystemswhichhavetandemsystembehaviour.Performanceevaluationoftandemsystemswithfeedbackscanbehandledwiththesemodels.However,becauseofthenumericaldifficultiescausedbylargestatespaces,consideringserverfailuresandrepairsatthesecondstageemployingmultipleservershasnotbeenpossible.Thesolutionproposedinthispaperisapproximatewithahighdegreeofaccuracy.Usingthisapproach,twostageopennetworkswithmultipleservers,breakdowns,andrepairsatthesecondstageaswellasfeedbackcanbemodelledasthree-dimensionalMarkovprocessesandsolvedforperformabilitymeasures.Resultsshowthat,unlikeotherapproachessuchasspectralexpansion,thesteadystatesolutionispossibleregardlessofthenumberofserversemployed.
ArticleOutline
1.Introduction
2.Twostagetandemnetworksunderstudy
3.Thethree-dimensionalsolutionapproach
4.Theaccuracyofthethree-dimensionalsolutionapproach
5.Theefficacyoftheproposedmethod
6.Conclusion
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HumanfactorsevaluationsofFreeFlight:
Issuessolvedandissuesremaining OriginalResearchArticle
AppliedErgonomics,Volume38,Issue4,July2007,Pages437-455
RobC.J.Ruigrok,JaccoM.Hoekstra
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Abstract
TheDutchNationalAerospaceLaboratory(NLR)hasconductedextensivehuman-in-the-loopsimulationexperimentsinNLR'sResearchFlightSimulator(RFS),focussedonhumanfactorsevaluationofFreeFlight.Eightyearsofresearch,inco-operationwithpartnersintheUnitedStatesandEurope,hasshownthatFreeFlighthasthepotentialtoincreaseairspacecapacitybyatleastafactorof3.Expectedtrafficloadsandconflictratesfortheyear2020appeartobenomajorproblemforprofessionalairlinecrewsparticipatinginflightsimulationexperiments.Flightefficiencyissignificantlyimprovedbyuser-preferredroutings,includingcruiseclimbs,whilepilotworkloadisonlyslightlyincreasedcomparedtotoday'sreference.
Detailedresultsfromthreeprojectsandsixhuman-in-the-loopexperimentsinNLR'sResearchFlightSimulatorarereported.Themainfocusoftheseresultsisonhumanfactorsissuesandparticularlyworkload,measuredbothsubjectivelyandobjectively.Anextensivediscussionisincludedonmanyhumanfactorsissuesresolvedduringtheexperiments,butalsoopenissuesareidentified.
Anintent-basedConflictDetectionandResolution(CD&R)systemprovides“benefits”intermsofreducedpilotworkload,butalso“costs”intermsofcomplexity,needforpriorityrules,potentialcompatibilityproblemsbetweendifferentbrandsofFlightManagementSystemsandlargebandwidth.Moreover,theintent-basedsystemisnoteffectiveatsolvingmulti-aircraftconflicts.Astate-basedCD&Rsystemalsoprovides“benefits”and“costs”.Benefitscomparedtothefullintent-basedsystemaresimplicity,lowbandwidthrequirements,easytoretrofit(norequirementstochangeavionicsinfrastructure)andtheabilitytosolvemulti-aircraftconflictsinparallel.The“costs”involveasomewhathigherpilotworkloadinsimilarcircumstances,thesmallerlook-aheadtimewhichresultsinlessefficientresolutionmanoeuvresandthesometimesfalse/nuisancealertsduetomissingintentinformation.
TheoptimalCD&Rsystem(intermsofcostsversusbenefits)hasbeensuggestedtobestate-basedCD&Rwiththeadditionofintendedortargetflightlevel.Thiscombinationofstate-basedCD&Rwithalimitedamountofintentprovides“thebestofbothworlds”.StudyingthisCD&Rsystemisstillanopenissue.
ArticleOutline
1.Introduction
1.1.Today'sproblems
1.2.Howthingsevolved
1.3.Definitionandexpectation
2.Studiesperformed
2.1.Pilotworkloadmeasurementsinstudies
2.1.1.Pilotsubjectiveworkload,acceptabilityandsafety
2.1.2.Pilotsemi-objectiveworkload
2.1.3.Pilotobjectiveworkload
2.2.Validationplatform
2.3.NLR/NASAFreeFlight
2.3.1.AirborneSeparationAssuranceSystem
2.3.2.Experiments
2.3.3.Results
2.4.INTENT
2.4.1.ASAS
2.4.2.Experiments
2.4.3.Results
2.5.MediterraneanFreeFlight(MFF)
2.5.1.ASAS
2.5.2.Experiments
2.5.3.Results
3.Discussion:
issuessolvedandissuesremaining
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AnefficientparalleloptimizationalgorithmfortheTokenBucketcontrolmechanism OriginalResearchArticle
ComputerCommunications,Volume29,Issue12,4August2006,Pages2281-2293
N.U.Ahmed,X.Lu,L.O.Barbosa
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Abstract
TheTokenBucketalgorithm,oneofthemostwidelyusedcontrolmechanismincomputercommunicationnetwork,hasbeenextensivelyusedtoensuretheQoSneedsforvariousapplications.Recently,[N.U.Ahmed,BoLi,LuisOrozco-Barbosa,Modellingandoptimizationofcomputernetworktrafficcontrollers,MathematicalProblemsinEngineering,2005,6(2005),617–640]anoptimizationtechnique,basedondynamicprogrammingandgeneticalgorithm,hasbeendevelopedwhichimprovesnetworkutilizationorthroughputbyreducingdatalossesandservicetime,etc.This,however,requireslongexecutiontimeandexcessivememoryspacetherebyimposinglimitationonitsapplicabilitytohighdimensionalproblems.Inthisstudywehaveconservedbothspaceandtimecomplexity.ThisisachievedbyintroducingmultipleprocessorsandtheReducedMemoryAlgorithmtherebyopeninguptheprospectsofsolvinglarge-scaleproblems.OurparallelprocessingalgorithmistestedwithMPEG-4traces.OurnumericalresultsshowthatthealgorithmcaneffectivelysolvethemultipleTokenBucketproblems.Theresultsalsoprovideuswiththeguidelinestoconfiguretheparallelprocessingplatform.
ArticleOutline
1.Introduction
1.1.Summaryofcontributionsofthispaper
1.2.Realtimeimplementation
2.Review
3.AdynamicmodeloftheTokenBucketalgorithm
4.Computationalcomplexity
5.AmultipleTokenBucketoptimizationalgorithm
5.1.Thereduced-memoryDynamicProgrammingalgorithm
5.2.Parallelprocessing
5.2.1.ParallelReducedMemoryAlgorithm
5.3.Algorithmflowcharts
5.4.Systemanalysis
5.4.1.OptimalnumberofPEs
5.4.2.Communicationcost
6.Systemplatformandparameters
6.1.Basicsystemparameters
6.2.Weightsassignedtodifferentlosses
7.Numericalresultsandanalysis
7.1.Runningtimeandspeedup
7.2.Parallelvs.sequentialalgorithms
7.2.1.Runningtimeanalysis
7.2.2.Memoryrequirementsanalysis
7.3.Optimalnumberofprocessors
8.Conclusion
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Optimumdesignofsquarefree-standingcommunicationtowers OriginalResearchArticle
JournalofConstructionalSteelResearch,Volume58,Issue3,March2002,Pages413-425
NabeelAbdulrazzaqJasim,AlaaChasebGaleb
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Abstract
Free-standingcommunicationtowerswithasquarecross-section,subjectedtomultiplecombinationsofwindanddeadloads,areoptimallydesignedforleastweight.Thememberareasandjointcoordinatesaretreatedasdesignvariablesofthetowertowhichareasonableinitialgeometryisspecified.Membersaredesignedtosatisfystress,displacementandbucklinglimits,inadditiontolinkingconstraintsbetweenareavariablesineachpanelofthetower.Thefullystresseddesignisassumedtobeoptimal.Coordinatevariablesarelinkedtoreducethenumberofindependentdesignvariables.Thedesignproblemis,ineffect,dividedintotwoseparate,butdependent,designspaces:
oneformembersizesandtheotherforjointcoordinates.Onchangingcoordinatevariables,usingtheHookeandJeveespatternsearchalgorithm,thememberareasaretreatedasdependentdesignvariables.Itisfoundthatthedecompositionoftheoptimizationproblemintoamultilevelproblemsimplifiestheprocedureforfindingtheoptimumdesignoffree-standingtowers.
ArticleOutline
1.Introduction
2.Formulationoftheoptimizationproblem
3.Optimizationoftowergeometry
4.Casestudies
4.1.Case1
4.2.Case2
5.Discussion
5.1.Optimumdesignformulationoffree-standingtowers
5.2.Effectoftheindependentdesignvariables
6.Conclusions
AppendixA.Theequalanglesectionsusedtodesignthetower
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Designofamulti-dimension