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