简介：

简介：这份报纸为全球阳光持续时间评价论述一个改进模型。方法论由包括雪盖子信息，阳光和卫星角度和一个趋势修正因素季节合并地球同步的卫星图象，为云盖子索引的决心。建议方法论的有效性与1h的时间的分辨率和2.5km瑵洠慥?汦睯?湡?慷?畦瑲敨?浥汰祯摥琠?瑳摵?桴?的空间分辨率在可见乐队用Meteosat地球同步的卫星图象被测试了晥敦瑣漠?桴?敭湡映潬?湯琠敨愠潣獵楴?数晲牯慭据?景琠敨洠?汦牥.閌?閌吗？？

简介：Themonitoringoftheradiationenvironmentofearth’sspacehasimportantsignificancefordevelopingspacescienceandapplicationtechniques.Themeasurementofspaceradiationincludesmainlytwoaspects:(1)measurementofenergyspectraandfluxofprotonandelectron,(2)theidentificationofparticlespecieslighter

简介：Themainobjectiveforthisresearchwastheanalyticalexplorationofthedynamicsofplanarsatelliterotationduringthemotionofanellipticalorbitaroundaplanet.First,werevisittheresultsofJ.Wisdometal.(1984),inwhich,bytheelegantchangeofvariables(consideringthetrueanomalyfastheindependentvariable),thegoverningequationofsatelliterotationtakestheformofanAbelordinarydifferentialequation(ODE)ofthesecondkind,asortofgeneralizationoftheRiccatiODE.WenotethatduetothespecialcharacterofsolutionsofaRiccati-typeODE,thereexiststhepossibilityofsuddenjumpinginthemagnitudeofthesolutionatsomemomentoftime.Inthephysicalsense,thisjumpingoftheRiccati-typesolutionsofthegoverningODEcouldbeassociatedwiththeeffectofsuddenacceleration/decelerationinthesatelliterotationaroundthechosenprincipleaxisatadefinitemomentofparametrictime.Thismeansthatthereexistsnotonlyachaoticsatelliterotationregime(aspertheresultsofJ.Wisdometal.(1984)),butakindofgradientcatastrophe(Arnold,1992)couldoccurduringthesatelliterotationprocess.Weespeciallynotethatifagradientcatastrophecouldoccur,thisdoesnotmeanthatitmustoccur:suchapossibilitydependsontheinitialconditions.Inaddition,weobtainedasymptoticalsolutionsthatmanifestaquasi-periodiccharacterevenwiththestrongsimplifyngassumptionse→0,p=1,whichreducethegoverningequationofJ.Wisdometal.(1984)toakindofBeletskii'sequation.

简介：Thelifetimeofanartificialsatellitemovinginthecircularorbitundertheactionofnonuniformrotatingatmosphericdragisstudiedfromanenergypointofviewinthispaper.Theangularvelocityofatmosphericrotationdecreaseswithheightaccordingtohydrodynamics.Theatmosphericdensitydecreaseswithheightaccordingtotheexponentialformula.Theexpressionforthelifetimeofasatelliteintheinstantaneouscircularorbitintheabove-mentionedrotatingatmosphericmodelisderived,andthenumericalestimationforthelifetimeofaconcretesatellitehasbeenmade.Theresultshowsclearlythatthesatellitelifetimecalculatedbythispaperisshorterthanthatcalculatedbytheuniformrotatingatmosphericmodel.

简介：Asetofparameterscalledrelativeorbitalelementsweredefinedtodescribetherelativemotionofthesatellitesintheformationflying.Withthehelpoftheseparameters,theeffectoftheperturbationsontherelativeorbittrajectoryandgeometricpropertiesofsatelliteformationcanbeeasilyanalyzed.First,therelativeorbitalelementsarederived,andpointedout:iftheeccentricityoftheleadingsatelliteisasmallvalue,therelativeorbittrajectoryisdeterminedbytheintersectionbetweenanellipticcylinderandaplaneintheleadingsatelliteorbitframereference;andtheparametersthatdescribetheellipticcylinderandtheplanecanbeusedtoobtaintherelativeorbittrajectoryandtherelativeorbitalelements.Second,byanalyzingtheeffectsofgravitationalperturbationsontherelativeorbitusingtherelativeorbitalelements,itisfoundthatthepropagationofarelativeorbitconsistsoftwoparts:oneisthedriftoftheellipticcylinder;andtheotheristherotationoftheplaneresultedfromtherotationofthenormaloftheplane.Meanwhile,theanalyticformulaeforthedriftandrotationratesofarelativetrajectoryundergravitationalperturbationsarepresented.Finally,therelativeorbittrajectoryandthecorrespondingchangeswereanalyzedwithrespecttotheJ2perturbation.

简介：Satelliteattitudeinformationisessentialforpico-satelliteapplicationsrequiringlight-weight,low-power,andfast-computationcharacteristics.Theobjectiveofthisstudyistoprovideamagnetometer-onlyattitudeestimationmethodforalow-altitudeEarthorbit,biasmomentumpico-satellite.Basedontwoassumptions,thespacecraftsphericalsymmetryanddampingofbodyrates,alinearkinematicsmodelofabiasmomentumsatellite'spitchaxisisderived,andthelinearestimationalgorithmisdeveloped.ThealgorithmcombinesthelinearKalmanfilter(KF)withtheclassicthree-axisattitudedeterminationmethod(TRIAD).KFisusedtoestimatesatellite'spitchaxisorientation,whileTRIADisusedtoobtaininformationconcerningthesatellite'sthree-axisattitude.Simulationtestsconfirmedthatthealgorithmissuitedtothetime-varyingmodelerrorsresultingfrombothassumptions.Theestimateresultkeepstrackingsatelliteattitudemotionduringalldamping,stable,andfreerotatingcontrolstages.Comparedwithnonlinearalgorithms,suchasextendedKalmanfiler(EKF)andsquarerootunscentedKalmanfiler(SRUKF),thealgorithmpresentedherehasanalmostequalperformanceintermsofconvergencetimeandestimationaccuracy,whiletheconsumptionofcomputingresourcesismuchlower.

简介：Awidevarietyofalgorithmshavebeendevelopedtomonitoraerosolburdenfromsatelliteimages.Still,fewsolutionscurrentlyallowforreal-timeandefficientretrievalofaerosolopticalthickness(AOT),mainlyduetotheextremelylargevolumeofcomputationnecessaryforthenumericsolutionofatmosphericradiativetransferequations.TakingintoaccounttheeffortstoexploittheSYNergyofTerraandAquaModis(SYNTAM,anAOTretrievalalgorithm),wepresentinthispaperanovelmethodtoretrieveAOTfromModerateResolutionImagingSpectroradiometer(MODIS)satelliteimages,inwhichthestrategyofblockpartitionandcollectivecommunicationwastaken,therebymaximizingloadbalanceandreduc-ingtheoverheadtimeduringinter-processorcommunication.ExperimentswerecarriedouttoretrieveAOTat0.44,0.55,and0.67mofMODIS/TerraandMODIS/Aquadata,usingtheparallelSYNTAMalgo-rithmintheIBMSystemCluster1600deployedatChinaMeteorologicalAdministration(CMA).Resultsshowedthatparallelimplementationcangreatlyreducecomputationtime,andthusensurehighparallelefficiency.AOTderivedbyparallelalgorithmwasvalidatedagainstmeasurementsfromground-basedsun-photometers;inallcases,therelativeerrorrangewaswithin20%,whichdemonstratedthattheparallelalgorithmwassuitableforapplicationssuchasairqualitymonitoringandclimatemodeling.