Building theADCIRC CollaborativeA federated approach to storm surge modeling and model output distribution toenable better decision support
C O N T A C T I N F O R M A T I O N
Brian BlantonTelephone: 919.445.9620Email: [email protected]
A R E N C I W H I T E P A P E R
Page 2RENCI White Paper SeriesRENCI White Paper Series
At a Glance• Strongcoastalstorms,inthe
formoftropicalcyclonesandextra-tropicalstorms,causeenormousdamage.Accuratepredictionofastorm’sim-pactscanhelpsavelivesandreducepropertydamage.
• ADCIRCisapowerfulmodelthatpredictstheimpactsofstormsurgeandwaveac-tionassociatedwithcoastalstormsatalevelofdetailandaccuracynotavailablefromothermodelingsystems.
• AnADCIRCcollaborative—aworkingrelationshipamongresearchcenterswithADCIRCcapabilities—willalloweffec-tiveandefficientdeploymentofADCIRCtosupportreal-timestormpredictionandon-the-groundpreparednessandresponse.
The TeamWrittenbyBrian Blanton,RENCISeniorResearchScientistandOceanographer,withcontributionsfromRick Luettich,Director,UNCHazardsCenterandUNCInstituteofMarineSciences,Jessica Losego,UNCInstitutefortheEnvironment,andJason Fleming,PrincipalEngineeratSeahorseCoastalConsulting.Additionalwritingsup-portfromAnne Frances Johnson.
ContactBrianBlanton,[email protected]
Vol.1,No.1intheRENCIWhitePaperSeries,August2013RenaissanceComputingInstituteUniversityofNorthCarolinaatChapelHill919-445-9640www.renci.org@renci
Summary
Strongcoastalstorms,includingbothtropicalcyclones(e.g.,hurri-canes)andextra-tropicalstorms(e.g.,nor’easters)routinelythreatenhumanlivesandproperty.Overthepastdecade,16stormsstriking
theAtlanticcoasthavecausedmorethan$1billionindamageeach,withotherstormscostingmanyhundredsofmillionsmore.HurricaneKatrinain2005,oneofthemostdevastatinginU.S.history,caused1,833deathsand$125billionindamage(NationalClimaticDataCenter2013).Muchofthedamagefromsuchstormscomesfromfloodingduetostormsurge(anabnormalriseinoceanwatercausedbyacoastalstorm),anddestructioncausedbylargewind-generatedwaves.
Accurate,detailed,andrapidstormpredictionscanhelpsavelivesandpreventpropertydamagebyinformingevacuationsandotheremergencypreparednessandresponseactivities.Stormimpactmodelsarealsocriti-caltolong-termplanningforcoastaldevelopment,infrastructure,andinsurance.Currentmodelsusedtopredictstormimpactsrequiretrade-offsbetweendetail,accuracy,andspeed.ADCIRCisapowerfulmodelthatspecializesinpredictingtheresponseofthecoastalocean,includingstormsurgeandwaveaction,causedbycoastalstorms.AlthoughADCIRCisbeingdeployedatseveralmajorresearchcentersandhasprovedhighlyvaluableforresearchandlong-termplanning,computingresourcechal-lengeslimititsgeneralutilityformakingtimelypredictionsduringactualstormevents.EstablishinganADCIRCcollaborative—aworkingrelation-shipamongresearchcenterswithADCIRCcapabilities—wouldoptimizethedeploymentofthismodelingsystemandenablereal-timeanalysisforthebenefitofcommunitiesaffectedbycoastalstorms.
The Challenge
Manyfactorscombinetomaketheconsequencesofcoastalstormsdifficulttopredict.Theyincludeaconfluenceofmultipleat-mosphericandoceanographicfactors—suchasairandocean
temperature,windspeed,winddirection,tides,stormsurge,andwaveaction—whichtheninteractwithanarrayofbuiltandnaturalstructures.Theimpactofstormsurge,whichisoftenresponsiblefortheextensivefloodingassociatedwiththesestorms,dependsonthesize,intensity,andtrajectoryofthestorm,aswellasthetopographyofthelandandthepresenceofstructuressuchasdunes,levies,orfloodwalls.Similarly,theimpactofwind-generatedwaves,responsibleformuchofthedamagetobuiltstructures,dependsonwindspeedandoceanographicfactors,aswellasthedesignofcoastalcommunities,buildingarchitecture,andotherfactors.Theabilitytoaccuratelypredictfloodingandstructuraldamageiscriticalforplanningroadclosuresandevacuationrouting,shelterandequipmentplacement,andrecoveryandrestorationefforts—allofwhichimpactastorm’shumanandmaterialtoll.
Twomodelsaremostfrequentlyusedforpredictingstormsurgeassociat-edwithcoastalstorms.ThemodeldevelopedbytheNationalOceanicandAtmosphericAdministration(NOAA)istheSea,LakeandOverlandSurgesfromHurricanes(SLOSH)model.SLOSHcanberuninashortenoughtimeintervaltoallowthecompletionofhundredsofmodelrunsbasedon
Page 3RENCI White Paper Series
differentpredictedstormtrajectoriesandproperties,whichcanthenbeusedtocreatemapsoftheprob-abilityoffloodinginstorm-impactedareas(Taylor&Glahn2008;Glahn,etal.2009).However,twoissueslimitSLOSH’saccuracy.First,SLOSHisnotwrittentoharnessmultiplecomputerCPUssimultaneously,sospatialresolutionmustbekeptrelativelycoarseforsimulationstofitontooneCPUandstillcompletequickly.Second,SLOSHrepresentsspatialfeaturesusinganorthogonalrectangulargrid,whichmakesitimpossibletoachievehighresolutioninthecoastalregionwithoutover-resolvingdeeperwater.Thistypi-callyresultsintheuseofmodeldomainsthataretoosmalltofullycapturethecoastalresponse.
Asecondmodel,ADCIRC,cancomputeextremelyhigh-resolution,detailed,andaccuratepredictions.ItiswrittentouseasmanycomputerCPUsasareavailable,andbecauseADCIRCusestrianglesasitsdescriptivebasis,themodel’sspatialresolutioncanbeveryhighinthecoastalzonewithoutover-resolvingdeeper,offshorewater(Westerink,etal.2008).Usingthisapproach,ADCIRCcangeneratemuchmoredetailedfloodforecastmapsthanSLOSH(seeFigure1).However,whenconfiguredtorunathighspatialresolution,ADCIRCrequiressignificantcomputingre-sources,makingeachrunofthemodelmoreresourceintensivethanSLOSH.
WhileSLOSHandADCIRCgenerallysolvethesameequationsforpredictingstormsurge,ADCIRC
incorporatestwoadditionalmechanismsdirectlyintoitssimulations:astronomicaltidesandbreakingwind-generatedwaves.Astronomicaltides,whicharecausedbythegravitationalattractionsbetweentheearth-moon-sunsystem,causetheperiodicfluctuationsofoceanicwaterlevelseenatthecoast.Themostdan-gerousstormsurgesandwavesarethosethatoccuratthesametimeashightide;however,thetimingofhightideislocation-specific,sothetimeofpeaktideinaninletorsoundmaybequitedifferentfromthetidetimingatanearbybeach.
ADCIRCdynamicallyincorporatesthetideineachmod-elrun,generatingalocation-specifictidalresponseandthereforeamoreaccuratepredictionofstormsurgeresponse.Inaddition,ADCIRCaccountsfortheimpactofwind-generatedwavesonstormsurge.Aswind-generatedwavesbreak,theycantransfermomentumtothestormsurge,increasingthewaterlevelofthestormsurgebyasmuchas5to15percentonwide,shallowcontinentalshelves(Dean&Dalrymple1991;Niedoroda,etal.2008)andsubstantiallymoreonnar-row,steepshelves(Resio&Westerink2008).ADCIRCiscoupledtotheSWANwind-wavemodelandthereforedirectlymodelsthewind-wavefieldandincorporatesthemomentumtransferfromthewavestothestormsurge.Accountingforastronomicaltidesandbreakingwind-generatedwavesimprovesADCIRC’saccuracy;however,italsoaddstothecomputingresourcesre-quiredtorunthemodel.
Figure 1:ADCIRC(graytriangles)andSLOSH(blacksquares)modelgridsintheWrightsvilleBeach,NCarea.BecauseADCIRCusestrianglesasitsdescriptivebasis,itallowsfloodpredictionatamuchgreaterlevelofdetailthanthecoarserSLOSHmodel,whichusessquares.TheredlineisthecoastlineinADCIRC’sgrid.
Theabilitytocomputeasiz-ableensembleofhigh-resolu-tionADCIRCrunswouldpro-videinformationonpredictionuncertaintyand,givenenoughruns(e.g.,100ormore),couldallowthecreationofextremelydetailedprobabilisticfloodandwave-impactpredictionstoguidedecisionmakingdur-ingcoastalstorms.However,severalkeychallengeslimittheutilityofADCIRCforreal-timeensemblesimulations:
1. Horsepower:Dependingonthesizeoftheareabeingmodeled,atypicalfive-daylongforecastruncantakeanhourormoreonseveralhundredtosev-eralthousandcomputer
Page 4RENCI White Paper Series
processors.Runningmultiplesimultaneoussimula-tionsrequiresmorecomputingpowerthancom-putingcentershaveavailableatanyonetime.
2. Cost: Duetoitshighdemandsoncomputingresources,ADCIRCcanimposesubstantialcostsinpersonnelandcomputingtime.
3. Time: Tobeusefulfordecisionmakingduringanactualstorm,predictionsmustbegeneratedinamatterofhoursorless.Few,ifany,computingcentershavetheavailablecapacitytoperformasizableensembleofhigh-resolutionADCIRCrunsinthistimeframe.Inaddition,thenatureoftropicalstormeventsmeanscomputingresourceswouldneedtobeavailableondemandwithashortwarn-ingperiod—asignificantobstacleforheavily-usedcomputingfacilities.
4. Output Translation: Forecasters, emergency
Ideas into Action: An ADCIRC Collaborative
ADCIRCispoisedtotransitionfromavaluableresearch/designmodelintoapowerfultoolforforecastguidanceanddecisionmaking.ADCIRC
alreadycontainsallofthetechnicalelementsneededtogenerateondemandeithersingledeterministicresultsoranensembleofresultsathighresolutionandtranslatethemforreal-world,real-timeforecasting.Butnosinglecomputingcentercaneasilyachievethisgoalalone.Whatisneededisacollaborativepartner-shipamongcomputingcentersequippedwithADCIRC.
TheUniversityofNorthCarolinaatChapelHill,UniversityofTexas,LouisianaStateUniversity,CollegeofStatenIslandattheCityUniversityofNewYork,andNOAA,areallexperiencedwithADCIRCandcomprisealogicalgrouptoformthebasisofsuchapartnership.
ThispartnershipwillpavethewayforADCIRCtobemoreefficientlyandeffectivelydeployed—andforpredictionresultstobedistributedtoforecastus-ers—wheneverastrongcoastalstormposesathreattotheU.S.coast.TheestablishmentoftheADCIRC
ADCIRCwasdevelopedintheearly1990sbyRickLuettichoftheUniversityofNorthCarolinaatChapelHillandJoannesWesterinkoftheUniversityofNotreDame(Luettich,etal.1992;Westerink,etal.2008).Whiletheyhavecontinuedtoleadmodeldevelopment(e.g.,Dietrich,etal.2011;Tanaka,etal.2011),inrecentyearsthebroaderADCIRCcommunity,comprisedoffederalgovern-ment,academic,andindustryusersandresearchers,hascontributedtoADCIRC’scontinueddevelopmentandim-provement,aswell.TheRenaissanceComputingInstitute(RENCI)helpstomaintaintheADCIRCcodeandservesasthemainADCIRCcoderepository.
Toaccuratelypredictstormsurgeathighresolution,ADCIRCincorporatesavarietyoffactorsaffectingthephysi-calforcesbehindstormsurge(forcingmechanisms),whichareaswillbeinundated(space),andwhenthegreatestimpactswilloccur(time).Thesefactorsinclude:
Forcing mechanisms
• Surfacewindandpressurefrommeteorological
modelsorhurricaneforecasttracks
• Wavebreakingforces
• Astronomicaltides
• Riverdischarge
Space
• Lineartriangularfiniteelements
• High-resolutiontopographyandbathymetry
• Hydraulicstructuresandraisedfeatures(levees,road-ways,channels)
• Locallandroughnessandtreecanopy
• ParallelimplementationviaMPI,DomainDecomposition(METIS)
Time
• Finitedifference,Courant–Friedrichs–Lewytime-steplimited
• User-specifiedmodeloutputrate;hourlysnapshotsofwaterlevelandwavesaretypical
ADCIRC Key Features
managersandotherkeydecisionmakersneedpre-dictivedatainformatsthatfitintodecisionmak-ingtoolsthatarealreadyinplace.Thus,ADCIRCoutputdataneedstobetranslatedintoformsthatarepracticalforuseontheground.
Federalcomputingfacilities(suchastheDepartmentofDefense’sCraysystemsinVicksburg,MS,andNOAA’sJetsystemsinBoulder,CO)havetheneces-saryhardwaretorapidlycreateADCIRCensemblepredictions,buttheseclustersandsupercomputersareheavilyusedandon-demandaccessisgenerallylimited.Atthefederallevel,therehashistoricallybeenmuchmoreemphasisplacedoncomputersimula-tionsofthemeteorologicalcomponentsofahurricaneitself,withlessemphasisoncomputingtheimpactsoftheseeventsintermsofstormsurge,waves,andevendamage.
Page 5RENCI White Paper Series
collaborativeisenvisionedintwophases.
Phase 1Phase1wouldconnectADCIRCoutputsfromallre-gionalcenterstocreateaunifiedviewofdatafromallADCIRCruns.Toachievethis,allsiteswouldcontributedatatoashareddatamanagementsystemusingstan-darddataformats,metadatadescriptions,anddataaccessprotocols.OneapproachwouldbetomanagethedatausingiRODS(integratedRules-OrientedDataSystem,anadvanceddatamanagementmiddleware,http://irods.org),anduseOPeNDAP(www.opendap.org)andUnidata’sTHREDDS(www.unidata.ucar.edu/projects/THREDDS)fordatacatalogingandaccess.
Ultimately,thesharedsystemwouldtranslatetheoutputdataintoWeb-basedvisualizationsandshape-filesforusebyforecastersandemergencymanagers.ConnectingandstandardizingtheoutputsfromallsitesrunningADCIRCwouldallowcriticalinformationtobeaccessedthroughasinglepoint-of-entry,regardlessofwhichcentergeneratedtheoutputdataorwhichareaswereimpactedbythestorm.
Phase 2InPhase1,onlyADCIRCoutputswouldbedealtwithcollectively.Phase2wouldallowADCIRCsitestogatherinputsandrunthemodelcollectively,thusenablingthecollaborativetorealizetheultimategoalofproducingensemblecalculationsathighresolutionondemand.Poolingthecomputingresourcesofmul-tiplesitesinthiswaywouldnotonlyallowthetimelygenerationofmoresimulationsofastorm-threatened
formalpolicyisneededthroughwhicheachADCIRCsitewouldpre-designatecompu-tationalpowerforon-demandusewhenastormthreatensthecoast,andthatwouldallowremoteADCIRCsystemstousesharedresources.Thisisasignificanthurdlegivenhighdemandsplacedonuniversitycomputeranddatacentersandcompetitionwithothertime-sensitivecomputationalneeds.
Figure 2: ConceptualdiagramofPhase1oftheADCIRCCollaborative.ExistingADCIRCsystemsareshowninblueandcoverthecoastalregionscoveredbytheovals.Plannedsystemsareshowninorange.Eachsys-tempublishesADCIRCmodelresultstoaTHREDDSserver.Currently,onlytheRENCITHREDDSserverisoperating.TheparticipatinggroupsaretheUniversityofTexasatAustin,LouisianaStateUniversity,RENCI,NOAA’sCoastSurveyDevelopmentLaboratory,andtheCollegeofStatenIslandattheCityUniversityofNewYork.ThecollectionofADCIRCresultsisrepresentedbythecloudandismaintainedbytheiRODS(integratedRule-OrientedDataSystem)datamanagementmiddleware.
ADCIRC already contains all of the technical elements needed to generate on demand either single, deterministic results or an ensemble of results at high resolution and translate them for real-world, real-time forecasting. But no single computing center can easily achieve this goal.
area,itwouldalsoprovideanimportantstructureforhandlingtwounlikely(butnotimpossible)scenarios:thattwoormorecoastalstormswouldthreatendif-ferentpartsofthecoastatthesametime,orthatanADCIRCsitewouldgoofflineduringastorm.
Attheconclusionofthisphase,allparticipatingADCIRCsystemswouldbeabletorespondtoanimpendingstormthreatanywherealongthecoastbyconductingmultiplesimultane-ousmodelruns.Theoutputsfromthesemodelrunswouldthenbeintegratedintohigh-resolutionprobabilisticpredictionsandtranslatedintousableformatstoinformdeci-sionmaking.
AchievingPhase2willrequireresearchontwofronts.First,researchisneededtodeterminethebestapproachforthesharedsystemtorequestremoteresources,stagetheneededmodelinputdatatotheremotesite,submittheparallelcomputation,andretrievethemodeloutput.Thisresearchisal-readyunderwayatRENCI,inprojectssuchasExoGENI(www.exogeni.net)andapplicationsoftheiRODSsoftwaretechnology.Second,a
Page 6RENCI White Paper Series
What Will It Take?
AnADCIRCcollaborativewouldaddressmanyofthechallengesthathavelimitedthereal-worldapplicationofthispowerfulsoftwarethusfar:
1. Horsepower:ThecollaborativewouldgreatlyincreasethecomputationalresourcesavailableforrunningADCIRCduringanactualstormevent.Bydrawinguponthecomputingcapacityofmultiplecomputingcenterssimultaneously,thecollabora-tivewouldallowcoordinated,redundant,parallelmodelruns,increasingthelikelihoodofgeneratingusefulresultsintherequiredtimewindow.Italsowouldallowmodelingofperturbationstoaccountfordifferentpathsthestormcouldtake,ultimatelyenablingthecreationofensemble-basedfloodingpredictions.Finally,itwouldensureADCIRCcouldcontinuetoruninmultiplestatesevenifonecen-terdropsofflineduetostormimpacts.
2. Cost:Acollaborativestructureallowsallcenterstoreapbenefitsfromsharedinfrastructureinvest-ments,reducingtheoverallcosttoeachcenter.Forexample,thesharedoutputsystemdeveloped
inPhase1wouldeliminatetheneedforeachcen-tertodevelopitsownmethodoftranslatingdataoutputsforusebyon-the-grounddecisionmakers,reducingredundancyandthusloweringcosts.
3. Time: ThecollaborativewouldallowmultiplesitestorunADCIRCsimultaneously,thusgeneratingusefulresultsmuchmorequicklythanwouldbefeasibleatanysinglesite.Inaddition,theagree-mentsputinplaceinPhase2wouldensurecom-putingresourcescanbeimmediatelyredirectedforADCIRCwhenastormposesathreat,allowingmodeloutputstobegeneratedintimetomakeadifference.
4. Output Translation: Ratherthanrequiringdatauserstoworkdirectlywithdataproducers,thecollaborativeoutputsystemsdevelopedinPhase1wouldhelpdatacontributorsofferpracticableinformationforuserswithoutneedingtocreatetheinterfacesthemselves.Thiswouldresultinaunified,streamlinedproductavailabletoforecast-ersandemergencymanagers.
TofullyunleashADCIRC’spotential,anewcol-laborativestructureisproposedthatchannelsthecollectiveresourcesofallADCIRC-equipped
centerswhenastrongstormthreatensthecoast.Suchastructurewouldlargelyovercomecurrentcomput-ingresourcelimitationsandultimatelyallowtheproductionofensemblecalculationsathighresolutionondemand.Theextremelydetailed,accuratestormimpactpredictionsgeneratedthroughthiseffortwoulddirectlybenefitemergencymanagersandthepublic—savinglivesandmoney.
ImplementationofPhaseIwillrequiretwocriticalcomponentsandcyberinfrastructureexperts.First,acapablewebprogrammermustbuildafront-endportaltodisplaythedesiredinformationcomingfromtheparticipatingADCIRCcenters.Thiswouldincludea“systemstatus”portalthatgathersreal-timeinforma-tionfromparticipatingcentersusinganAMQPimple-mentationlikeRabbitMQtotrackthestatusofsimula-tions(forexample,pending,running,complete,failed),
collectensemblememberinformation,andlinktotheoutputfilesondataservers.
Second,atechnicianwithknowledgeofthemethodsusedwithADCIRCmusthelpmaintaintheautomatedsoftwareonparticipatingcomputingresourcesandsolveunanticipatedissuesthatariseinfederatingmul-tipleADCIRCinstancesthroughthecollaborativedatagridusingiRODS.
PhaseIIwillrequiremaintenanceofPhaseIactivitiesandtheexpansionoftheweb-basedresultstoincludeeffectivedisplayofensembleresultsandprobabilisticassessments,andtoorganizeandimplementacoordi-natedsetofmodelrunsacrossdistributedresources.TheresourcesharingaspectsofPhaseIIwillrequirepolicyagreementsbetweenparticipatingcentersandadministratorstoenablecross-centercommunicationandcooperation,aswellasadoptionofcomputere-sourcequeuesthatallowpreemptiveandon-demandsimulationsduringstormevents.
This partnership will pave the way for ADCRIC to be more efficiently and effectively deployed—and for prediction results to be distributed to forecast users—whenever a strong coastal storm poses a threat to the U.S. coast.
The Upshot
Page 7RENCI White Paper Series
ReferencesDean,R.G.&Dalrymple,R.A.(1991).Waterwavemechanicsforengineersandscientists.WorldScientific.
Dietrich,J.C.,Zijlema,M.,Westerink,J.J.,Holthuijsen,L.H.,Dawson,C.,Luettich,R.A.,Jensen,R.,Smith,J.M.,Stelling,G.S.,Stone,G.W.(2011).Modelinghurricanewavesandstormsurgeusingintegrally-coupled,scalablecomputations.CoastalEngineering,58,45-65.
Glahn,B.,Taylor,A.,Kurkowski,N.,&Shaffer,W.A.(2009).TheroleofthesloshmodelinNationalWeatherServicestormsurgeforecasting.NationalWeatherDigest,33(1),3-14.
Luettich,R.A.,Westerink,J.J.,&Scheffner,N.W.(1992).ADCIRC:anadvancedthree-dimensionalcirculationmodelforshelvescoastsandestuaries,report1:theoryandmethodologyofADCIRC-2DDIandADCIRC-3DL.DredgingResearchProgramTechnicalReportDRP-92-6,U.S.ArmyWaterwaysExperimentStation,Vicksburg,MS,137pp.
NationalClimaticDataCenter.Billion-DollarWeather/ClimateDisasters.http://www.ncdc.noaa.gov/billions/overview[AccessedJuly2,2013]
Niedoroda,A.,Das,H.,Slinn,D.,Dean,R.,Weaver,R.,Reed,C.,&Smith,J.(2008).Theroleofwaveset-upduringextremestorms.Proceedingsofthe31stInternationalConferenceonCoastalEngineering,1,250–261.
Resio,D.T.&Westerink,J.J.(2008).Modelingthephysicsofstormsurge.PhysicsToday,61,33-38.
Tanaka,S.,Bunya,S.,Westerink,J.J.,Dawson,C.,Luettich,R.A.(2011).Scalabilityofanunstructuredgridcontinu-ousGalerkinbasedhurricanestormsurgemodel.JournalofScientificComputing,46,329-358.
Taylor,A.A.,&Glahn,B.(2008).Probabilisticguidanceforhurricanestormsurge.http://www.nws.noaa.gov/mdl/psurge/talks/PsurgeAMS_20080115.pdf[AccessedJuly2,2013]
Westerink,J.,Luettich,R.,Feyen,J.,Atkinson,J.,Dawson,C.,Roberts,H.,Powell,M.,Dunion,J.,Kubatko,E.,&Pourtaheri,H.(2008).Abasin-tochannel-scaleunstructuredgridhurricanestormsurgemodelappliedtoSouthernLouisiana.MonthlyWeatherReview,136,833-864.
RENCIisaninstituteoftheUniversityofNorthCarolinaatChapelHillthatdevelopsanddeploysadvancedtechnologiestoenableresearchdiscoveriesandpracticalinnovations.RENCIpartnerswithresearchers,policymakers,andtechnologyleaderstoengageandsolvethechallengingproblemsthataffectNorthCarolina,ournationandtheworld.Theinstitutewaslaunchedin2004asacollaborativeeffortinvolvingUNCChapelHill,DukeUniversityandNorthCarolinaStateUniversity.Formoreinformation,seewww.renci.org.
About RENCI
How to reference this paper:
Blanton,B.,Luettich,R.,Losego,J.,Fleming,J.&Johnson,A.F.(2013):BuildingtheADCIRCCollaborative.RENCI,UniversityofNorthCarolinaatChapelHill.Text.http://dx.doi.org/10.7921/G0RN35SG
Top Related