Effectiveness of early replies in clientserver systems.docx

Effectiveness of early replies in clientserver systems.docx

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Effectivenessofearlyrepliesinclientserversystems

Aclient-basedloggingtechniqueusingbackwardanalysisofloginclient/serverenvironment  OriginalResearchArticle

JournalofSystemsandSoftware

practicalcomputingalgorithmworkinginrealtimehasbeendevelopedforcalculationsofthereflectionhigh-energyelectrondiffractionfromthemolecularbeamepitaxygrowingsurface.Thecalculationsarebasedonadynamicaldiffractiontheoryinwhichtheelectronsarescatteredonapotential,whichisperiodicinthedirectionperpendiculartothesurface.

Newversionprogramsummary

Titleofprogram:

RHEED_v2

Catalogueidentifier:

ADUY_v1_1

ProgramsummaryURL:

http:

//cpc.cs.qub.ac.uk/summaries/ADUY_v1_1

Programobtainablefrom:

CPCProgramLibrary,Queen'sUniversityofBelfast,N.Ireland

Catalogueidentifierofpreviousversion:

ADUY

Authorsoftheoriginalprogram:

A.Daniluk

Doesthenewversionsupersedetheoriginalprogram:

Yes

Computerforwhichthenewversionisdesignedandothersonwhichithasbeentested:

Pentium-basedPC

Operatingsystemsormonitorsunderwhichthenewversionhasbeentested:

Windows9x,XP,NT,Linux

Programminglanguageused:

C++

Memoryrequiredtoexecutewithtypicaldata:

morethan1MB

Numberofbitsinaword:

64bits

Numberofprocessorsused:

1

Numberofbytesindistributedprogram,includingtestdata,etc.:

1 074 131

No.oflinesindistributedprogram,includingtestdata,etc.:

3408

Distributionformat:

tar.gz

Natureofphysicalproblem:

Reflectionhigh-energyelectrondiffraction（RHEED）isaveryusefultechniqueforstudyingthegrowthandthesurfaceanalysisofthinepitaxialstructurespreparedbythemolecularbeamepitaxy（MBE）.RHEEDrockingcurvesrecordedfromheteroepitaxiallayersareusedforthenon-destructiveevaluationofepilayerthicknessandcompositionwithahighdegreeofaccuracy.Rockingcurvesfromsuchheterostructuresareoftenverycomplexbecausethethicknessfringesfromeverylayerbeattogether.Simulationsbasedondynamicaldiffractiontheoryaregenerallyusedtointerprettherockingcurvesofsuchstructuresfromwhichverysmallchangesinthicknessandcompositioncanbeobtained.Rockingcurvesarealsousedtodeterminethelevelofstrainanditsrelaxationmechanisminalattice-mismatchedsystem.

Methodofsolution:

Thenewversionoftheprogramretainsthedesignandstructureofthepreviousone[A.Daniluk,Comput.Phys.Comm.166（2005）123.[1]].

Reasonsforthenewversion:

RespondingtotheuserfeedbackwepresentedanextensionoftheRHEEDprogramthatenablescomputingthecrystallinepotentialsforepitaxialheterostructuresandcorrespondingvaluesoftheamplitudeoftheRHEEDintensityoscillations.

Summaryofrevisions:

（1）InthispaperweshowhowthedynamicalapproachmaybeappliedtocreationofapracticalcomputingalgorithmtocalculateoftheintensityofthespecularlyreflectedRHEEDbeamduringMBEgrowthofPbonSi（111）.ThestructuralpropertiesofthePb

Siinterfacehavebeen

Fig.1. Contracteddivisionofthesubstrateandsurfacelayersintoanassemblyofnatomiclayersandithinslicesparalleltothesurface.

[b]

Fig.2. One-dimensional（z-direction）potentialofPb/Si（111）at70K.

Fig.3. Computersimulatedone-beamrockingcurveforsomePblayersonaSi（111）substrate.

meticulouslystudiedbyHowesandco-workers[P.B.Howes,K.A.Edwards,D.J.Hughes,J.E.Macdonald,T.Hibma,T.Bootsma,M.A.James,Surf.Sci.Lett.331（1995）646;K.A.Edwards,P.B.Howes,J.E.Macdonald,T.Hibma,T.Bootsma,M.A.James,Surf.Sci.424（1999）169.[2]and[3]],andLucasandLoretto[C.A.Lucas,D.Loretto,Surf.Sci.Lett.344（1995）1219.[4]]（X-raydiffraction）.ThenewversionoftheRHEEDprogramhasthesamedesignasthepreviousone[A.Daniluk,Comput.Phys.Comm.166（2005）123.[1]].Tosimulatethestructuralvariationsofwholecrystallineheterostructurealongthesurfacenormaldirectionthesubstrateandlayersaredividedintoanassemblyofnatomiclayers.EachoftheselayersisfurtherdividedintoanassemblyofithinslicesparalleltothesurfaceandeachsliceisassumedtohaveaconstantpotentialnormaltothesurfaceasshowninFig.1.TheFouriercomponentofthescatteringpotentialofthewholecrystallineheterostructurecanbedeterminedasasumofcontributionscomingfromallthinslicesofnindividualatomiclayers.Tocarryoutone-dimensionalcalculationsweusedtheself-consistentthicknessZi_Substrate（）,thicknessZi_Layers（）,thicknessZn_Substrate（）,thicknessZn_Layers（）,crystPotUgSubstrate（）andcrystPotUgLayers（）functions.Fig.2presentsthecrystallinepotentials（realpart）calculatedforsomePblayersonaSi（111）substrateat70K.Fig.3showsadynamicallycalculatedone-beamrockingcurveforPb/Si（111）.

Fig.4. ThenumberOfLayersandNLayersconstantparametersshouldbeinitiatedto0duringcalculationscarryingoutformonocrystallinesubstrate.

Fig.5. ThethicknessZi_Layers（）,thicknessZn_Layers（）andcrystPotUgLayers（）functionsarenotusedduringcalculationsformonocrystallinesubstrate.

（2）Thepresentedalgorithmisageneralizationofthepreviousone.Byattributing0tothenumberOfLayersandNLayersconstantparameters（Fig.4）andremovingappropriatefunctionsfromthemainprogram（Fig.5）,weobtainthesameresultsasinthecaseofmonocrystal[A.Daniluk,Comput.Phys.Comm.166（2005）123.[1]].

Typicalrunningtime:

Thetypicalrunningtimeismachineanduser-parametersdependent.

Unusualfeaturesoftheprogram:

TheprogramispresentedintheformofabasicunitRHEED_v2.cpp.Itisnottiedtoanyspecifichardwareandsystemssoftwareplatform,andcouldbecompiledusingC++compilers,includingC++Builder,VC++andg++.

Web-enabledconfigurationandcontroloflegacycodes:

Anapplicationtooceanmodeling  OriginalResearchArticle

OceanModelling

Anadaptiveneuralnetworkstrategyforimprovingthecomputationalperformanceofevolutionarystructuraloptimization  OriginalResearchArticle

ComputerMethodsinAppliedMechanicsandEngineering

Themainpartofthecodepresentedinthisworkrepresentsanimplementationofthesplit-operatormethod[J.A.Fleck,J.R.Morris,M.D.Feit,Appl.Phys.10（1976）129–160;R.Heather,Comput.Phys.Comm.63（1991）446]forcalculatingthetime-evolutionofDiracwavefunctions.ItallowstostudythedynamicsofelectronicDiracwavepacketsundertheinfluenceofanynumberoflaserpulsesanditsinteractionwithanynumberofchargedionpotentials.TheinitialwavefunctioncanbeeitherafreeGaussianwavepacketoranarbitrarydiscretizedspinorfunctionthatisloadedfromafileprovidedbytheuser.ThelatteroptionincludesDiracboundstatewavefunctions.Thecodeitselfcontainsthenecessarytoolsforconstructingsuchwavefunctionsforasingle-electronion.Withthehelpofself-adaptivenumericalgrids,weareabletostudytheelectrondynamicsforvariousproblemsin2+1dimensionsathighspatialandtemporalresolutionsthatareotherwiseunachievable.

Alongwiththepositionandmomentumspaceprobabilitydensitydistributions,variousphysicalobservables,suchastheexpectationvaluesofpositionandmomentum,canberecordedinatime-dependentway.Theelectromagneticspectrumthatisemittedbytheevolvingparticlecanalsobecalculatedwiththiscode.Finally,forplanningandcomparisonpurposes,boththetime-evolutionandtheemissionspectrumcanalsobetreatedinanentirelyclassicalrelativisticway.

Besidestheimplementationoftheabove-mentionedalgorithms,theprogramalsocontainsalargeC++classlibrarytomodelthegeometricalgebrarepresentationofspinorsthatweuseforrepresentingtheDiracwavefunction.Thisiswhythecodeiscalled“Dirac++”.

Currently,thereisaplethoraoflow-costcommercialoff-the-shelf（COTS）hardwareavailableforimplementingcontrolsystems.Theserangefromdeviceswithfairlylowintelligence,e.g.smartsensorsandactuators,todedicatedcontrollerssuchasPowerPC,programmablelogiccontrollers（PLCs）andPC-basedboardstodedicatedsystems-on-a-chip（SoC）ASICSandFPGAs.Whenconsideringtheconstructionofcomplexdistributedsystems,e.g.foraship,aircraft,car,train,processplant,theabilitytorapidlyintegrateavarietyofdevicesfromdifferentmanufacturersisessential.Aproblem,however,isthatmanufacturersprefertosupplyproprietarytoolsforprogrammingtheirproducts.Asaconsequenceofthislackof‘openness’,rapidprototypinganddevelopmentofdistributedsystemsisextremelydifficultandcostlyforasystemsintegrator.Greatopportunitiesthusexisttoproducehigh-performance,dependabledistributedsystems.However,thekeyelementthatismissingissoftwaretoolsupportforsystemsintegration.TheobjectiveoftheFlexibleControlSystemsDevelopmentandIntegrationEnvironmentforControlSystems（FLEXICON）projectIST-2001-37269istosolvetheseproblemsforindustryandreducedevelopmentandimplementationcostsfordistributedcontrolsystemsbyprovidinganintegratedsuiteoftoolstosupportallthedevelopmentlife-cycleofthesystem.WorkwithintheRolls-RoycesupportedUniversityTechnologyCentre（UTC）isinvestigatingrapidprototypingofcontrollersforaero-engines,unmannedaerialvehiclesandships.Thispaperdescribestheuseofthedevelopedco-simulationenvironmentforahigh-speedmerchantvesselpropulsionsystemapplication.

ArticleOutline

1.Introduction

2.FLEXICONtoolset

3.Co-simulationenvironmentbasedonCORBA

3.1.CORBAapproach

4.Marineapplication

5.Co-simulationforthemarineapplication

5.1.Captainsinterface

5.2.Co-simulationinterface—ISaGRAFandSimulink

5.2.1.Prop