Loading...

Table of Content

    25 June 2016, Volume 36 Issue 3 Previous Issue    Next Issue
    For Selected: Toggle Thumbnails
    MobilitymanagementinLEOsatellitecommunicationnetworks
    HE Da-Jian, YOU Peng, YONG Shao-Wei
    2016, 36 (3):  1-14.  doi: 10.16708/j.cnki.1000-758X.2016.0034
    Abstract ( 729 )   PDF (1144KB) ( 1586 )   Save
    Inrecentyears,lowEarthorbit(LEO)satellitecommunicationnetworksattractalotofresearchers'attentionforitsglobalcoverage,shortpropagationdelay,low-powerlinksandgreatinvulnerabilityperformance,etc.Itwillbeanimportantpartofthefutureglobalmobilecommunicationsystems.MobilitymanagementisakeytechnologyforenablingserviceinLEOsatellitecommunicationnetworks.Thecharacteristics,researchstatusandproblemsofmobilitymanagementwereanalyzed.Firstly,abriefclassificationofmobilitymanagementofLEOsatellitecommunicationsnetworkswasprovidedandcharacteristicsdistinguishedfromterrestrialmobilitywirelessnetworkswereanalyzedbasedonthearchitectureandfeaturesofLEOsatellitecommunicationnetworks.Thenthestate-of-the-artmobilitymanagementschemesinLEOsatellitecommunicationnetworksweresummarizedfromlinklayer,networklayerandtransportlayer.AdetaileddescriptionoftheapplicationofMIPv6andSIGMAinLEOsatelliteenvironmentwasgiven.Finally,sometrendsofmobilitymanagementofLEOsatellitecommunicationsnetworkswaspointedout.
    Related Articles | Metrics
    Non-equilibriumnumericalsimulationofalowpowernitrogen/hydrogenarcjet
    WEI Yan-Ming, HE Qing-Song, WANG Hai-Xing
    2016, 36 (3):  15-23.  doi: 10.16708/j.cnki.1000-758X.2016.0035
    Abstract ( 696 )   PDF (1595KB) ( 814 )   Save
    Thermalandchemicalnonequilibriummodelingsstudywereperformedonalowpowernitrogen/hydrogenarcjet.Separateenergyequationswereformulatedfortheelectronsandtotalspecies,andsevenspeciesnitrogen/hydrogenplasmacompositionofmolecules,atoms,ionsandelectronswasassumed.Someimportantchemicalkineticprocessesofdissociationandionizationwereconsideredinthechemicalnonequilibriummodel.Theplasmapropertieswerecalculatedaccordingtothelocalspeciesnumberdensityandtemperature.Thedistributionoftemperatureandthenumberdensityofeachspeciesinthearcjetwereobtained.Theresultsshowthattheaxisofarcjetisclosetothermalequilibriumandsignificantdeviationfromthermalequilibriumisfoundinthearcattachmentregion.Itisshownthatthespeciesdistributionsofnitrogenandhydrogenaresignificantlydifferentfromthoseattheinletofthruster,whichindicatesthatthereexistthedemixingprocessesinsidethruster.Itisfoundthatthehydrogenspeciesdecreaseatfirstandthenincreasealongtheradialdirectionfromthecentertotheinnerwallofthruster,whilethenitrogencomponentsshowtheoppositetrend.Furtheranalysisshowsthatthespeciesdiffusionsinsidearcjetaredrivenbymolefractiongradientswhichareduetothedissociationandionizationofnitrogenandhydrogenspecies.
    Related Articles | Metrics
    Analysisonflexiblespacemanipulatorsystemassisteddockingofspacestation
    WEI Qing-Qing, WANG Yao-Bing, TANG Zi-Xin, ZHANG Da-Wei
    2016, 36 (3):  24-31.  doi: 10.16708/j.cnki.1000-758X.2016.0036
    Abstract ( 894 )   PDF (1288KB) ( 965 )   Save
    Positionerrorsandangleerrorsexistinevitablyinspacemanipulatorsystemassisteddockingofspacecraft.Adynamicandcontrolmodelconcernedthecontactionbetweenthedockingsystemwassetuptosimulatethespacemanipulatorsystemassisteddockingofspacecraft.Theimpedancecontrolsystemassociatedwiththedetailedjointdynamicmodel,jointtorquecontrolsystemwasbuilt.Theresultsshowthatthespacemanipulatorsystemcouldovercometheinitialerrorofthespacecraft,andfinishthejobofspaceassisteddocking.Thecontrolforceturneddownimmediatelyafterthespacecraftwasdocked.Also,thespacemanipulatorsystemcouldholdthepositionandshape.
    Related Articles | Metrics
    Multi-GNSSRAIMavailabilityalgorithmsandanalysisforpreciseapproach
    JIANG Hu, YUAN Yun-Bin, WANG Hai-Tao, OUJi-Kun , JIANG Zhen-Wei
    2016, 36 (3):  32-40.  doi: 10.16708/j.cnki.1000-758X.2016.0028
    Abstract ( 756 )   PDF (24780KB) ( 383 )   Save
    Withthecontinuousdevelopmentofglobalnavigationsatellitesystem(GNSS),thecombinedmulti-systemreceiverautonomousintegritymonitoring  (RAIM)hasbeenanimportanttopicbasedonBDS/GPS/GLONASS/Galileo.ThealgorithmofMulti-GNSSRAIMavailabilitywasproposed,andtheavailabilityofacombinedmulti-systemRAIMbasedonsimulatednavigationephemerisofBDS/GalileoandactualnavigationephemerisofGPS/GLONASSwasanalyzedinpreciseapproachprocedures.Resultsshowthatfivegeosynchronousorbit(GEO)satellitesandthreeinclinedgeosynchronousorbits(IGSO)satellitesfromBDSmakeagreatcontributiontoRAIMavailability.TheeightsatellitesimprovethegeometrystructureoftheconstellationinthemostpartsofAsia,AfricaandEurope,andpromoteRAIMavailabilitygreatly.IntheAsia-Pacificregion,theRAIMavailabilityofBDSreaches99.5%,higherthanthatoftheotherthreenavigationsystematAPVIphase.Inpreciseapproachphases(APV-I,APV-IIandCAT-I),theintegratedBDS/GPS/Galileo/GLONASScanmeettherequirementsofRAIMavailabilityinaglobalscale.
    Related Articles | Metrics
    Dynamicsanalysisoflineararraydeployablestructurebasedonscissor-likeelementconsideringjointclearance
    LI Bo, WANG San-Min, YUAN Ru, ZHI Chang-Jian
    2016, 36 (3):  41-49.  doi: 10.3780/j.issn.1000-758X.2016.0020
    Abstract ( 752 )   PDF (1153KB) ( 1310 )   Save
    Inordertopreciselyresearchthedynamicsperformanceofadeployablestructurebasedonascissor-likeelement,clearanceswereintroducedintooneofalljointsinthescissor-likeelementsothatitwasclosedtotherealmechanism.Thekinematicmodeloftherevolutejointwithclearancewasestablishedbytheprincipleofthemotionbetweenjointelements.ThenormalandtangentialcontactforcesbetweenjointelementsweredescribedbyaGonthiercontactforcemodelandacorrectionalCoulombfrictionmodel.Thecontactforcesbetweenthebearingandthejournalwereconvertedtothemasscentersoflinkandthesliderconnectedbythisclearancejoint.Theconvertedcontactforceandtheadditionaltorquewereintegratedtoageneralizedforceinmotionequationsofthedeployablestructure,andthentheeffectofjointclearancewasintroducedtothescissor-likeelement.Adirectdefaultcorrectionmethodwasusedtodirectlymodifythecoordinatesandspeedsofthesystemtoavoidthenumericalresultsdivergence.Also,thismethodcancontrolthedefaultwithinagivenrangeofaccuracy.Theinfluenceofrevolutejointclearanceonthedynamicperformanceofthelineararraydeployablestructurewaspredictedbymeansofnumericalanalysis,providingareferenceandbasisforthestudyofthemotionaccuracyandmechanismdesignofdeployablestructures.Furthermore,thesimulationresultsextendtheapplicationrangeoftheclearancecollisionmodel,whichishelpfulforengineeringapplications.
    Related Articles | Metrics
    Avariable-fidelitysequentialoptimizationmethodforreentrytrajectoryofspaceplane
    ZHU Jun-Jie, YU Xiong-Qing*, LUO Dong-Ming, WANG Yu
    2016, 36 (3):  50-56.  doi: 10.16708/j.cnki.1000-758X.2016.0032
    Abstract ( 749 )   PDF (1164KB) ( 1002 )   Save
    Avariable-fidelitysequentialoptimizationmethodforreentrytrajectorydesignofaspaceplanewasproposedtoincreaserobustnessandaccuracyoftheoptimization.Theoptimizationprocessconsistedofthreesteps.Firstly,  therewasapreoptimization,inwhichforacoarsediscretecase,theoptimalsolutionofdesignvariablesforeachdiscretizedpointwasobtainedbyusingahybridoptimizationmethod.Secondly,  initialvaluesofthediscretizedpointsinarefineddiscretecasewereobtainedbyusinglinearinterpolationfromthepre-optimizationsolution.Finally,thetrajectoryoptimizationintherefineddiscretecasewasconducted,andmoreaccurateoptimizationresultswereobtained.Ademonstrationexamplewasusedtovalidatetheproposedmethod.Theresultsindicatethatthereentrytrajectoryoptimizationproblemcanbesolvedrobustlywithsatisfiedaccuracyandlesscomputationalburden.
    Related Articles | Metrics
    Anapproachtoanalyzetherangeofsolardisturbanceforattitudesensorofspacecraft
    CAI Jian, SONG Li-Fang, JIANG Qing-Hua
    2016, 36 (3):  57-62.  doi: 10.16708/j.cnki.1000-758X.2016.0029
    Abstract ( 663 )   PDF (1576KB) ( 916 )   Save
    Thereislimitationtoconfirmingthereasonforthedatachangeofattitudesensorofspacecraftafterthetelemetrydatawerereceived,whichbringstheproblemthatthedatacan′tbeanalyzedintime.Tosolvethisproblem,anapproachwasproposedtostudytherangeofsolardisturbanceforattitudesensorbasedontwoangleparameterswhichreflectrelativepositionbetweenthesunandspacecraft.Therangeofsolardisturbanceforattitudesensorcouldgaininadvanceduetowellregulatedchangeofthetwoparameters.Consequently,whichcouldofferhelpfordatachangeandfailureanalysisofattitudesensor.Furthermore,itisbeneficialtothedesignofspacecraftattitudecontrolsystem,forexample,configurationandinstallationofattitudesensor.Inaddition,thefacultytorestrainsunlightofattitudesensorisvalidatedthroughtheway.Simulationresultsprovethevalidityofthealgorithm.
    Related Articles | Metrics
    Researchonmechanicalcharacteristicsoflunarspaceelevators
    LI Meng, CHEN Wei-Yue, YANG Sheng, GAO Xu
    2016, 36 (3):  63-69.  doi: 10.16708/j.cnki.1000-758X.2016.0030
    Abstract ( 739 )   PDF (3142KB) ( 701 )   Save
    Themechanicalandmasscharacteristicsaredeterminedbythestructureoflunarspaceelevator.
    Mostofcurrentresearchesaboutlunarspaceelevatorsonlyfocusoncombined-cross-sectionstructure.Variousstructuresoflunarspaceelevatorswereinvestigated.Toanalyzethemechanicalandmasscharacteristics,thedynamicmodelofthespaceelevatorwasestablished.Bysupposingthedensityandstressasconstantrespectively,twodifferentkindsoflunarspaceelevatorscalledfixed-cross-sectionstructureandtapered-cross-sectionstructurewereobtainedandcompared.Theresultsshowthatthemaximumstressoftapered-cross-section-structurecanbedesignedasanyconstantvalue,whichreducestherequirementofmarginstressofthematerial.Asaresult,tapered-cross-sectionstructurealsohastheleastmass,whichcouldbeconsideredastheoptimalchoice.
    Related Articles | Metrics
    Numericalsimulationoflunarsoiltemperatureconsideringitsvariablethermalproperties
    LUO Zu-Fen, SONG Bao-Yin, CAO Xi
    2016, 36 (3):  70-76.  doi: 10.16708/j.cnki.1000-758X.2016.0031
    Abstract ( 652 )   PDF (3142KB) ( 806 )   Save
    Thethermaldesignoflunarexplorationdevicesandinstrumentsdependsonrealinformationofthethermalenvironmentofthelunarsurface.UsingthethermalanalysismoduleinANSYS,andconsideringthatthethermalconductivityofthelunarsoilvarieswithbothdensityandtemperatureandthespecificheatisafunctionoftemperature,alunarsoiltemperaturesolvingmodelwasdeveloped.Andthelunarsurfacetemperaturesatthelatitudeof26°andtheequatorwerethencalculatedrespectively.Thetemperaturedistributionofsuperficiallayersattheequatorwasalsodiscussed.Thegoodagreementofthecomputedresultsandthemeasureddatainlunarsurfacetemperaturesrevealsthatthemodelandtheselectedparametersareapplicableandreliable,besides,thefurthermatchedpredictingresultsandmeasureddatawithasomewhatmodifiedlunarsoilconductivitypartlyshowthefunctionofthemodelincalculatingthelunarsoiltemperature.Todiscussthetemperaturedistributionofsuperficiallayersattheequator,thelunarsoiltemperatureandtheheatfluxprofilesatdifferenttimeswereplotted,andtheeffectsofthelunarinnerheatfluxandtheconductivityofthelunarsoilonthesoiltemperaturewerealsoanalyzed,whichmighttheoreticallysupportthethermaldesignsforlunarexplorationdevicesorinstruments.
    Related Articles | Metrics
    InclinationandeccentricitycombinationcontrolmethodusingelectricpropulsionforGEOsatellitestationkeeping
    LI Qiang, ZHOU Zhi-Cheng, YUAN Jun-Gang, WANG Min
    2016, 36 (3):  77-84.  doi: 10.16708/j.cnki.1000-758X.2016.0037
    Abstract ( 822 )   PDF (1436KB) ( 1010 )   Save
    NowadaysmostadvancedGEOsatellitescollocateelectricthrusterswithhighspecificimpulsetoexecutenorth-southstationkeeping,whichcanefficientlydecreasepropellantconsumption.ForGEOsatellites,electricthrustersusuallycontrolsnothingbutinclination,whilebipropellantthrustercontrolseccentricityandmeanlongitude.AimingatthestationkeepingofGEOsatellitewithelectricthruster,asortofcombinationcontrolmethodofinclinationandeccentricityusingelectricthrusterswasproposed.Theoptimizationmodelforsolvingthecontrolequationswasdeveloped.Twokindsofsimplifiedalgorithmwereinducedbyreducingtheoptimizationmodeldimensionality,whichdeeplydecreasethecomputationalcomplexityandwasconvenientforautonomouscomputationofGEOsatellitestationkeeping.Thismethodcanbeusedtosimulatethecombinedinclinationandeccentricitysimultaneouslyandprecisely,whichleadstothereductionofpropellantconsumptionforstationkeeping.Thesimulationresultsindicatethatthecombinationcontrolmethodhastheadvantagesofhighstationkeepingefficiencyandhighcontrolprecision.
    Related Articles | Metrics
    Redundantthrusterconfigurationdesignandcommandallocationalgorithmofmannedmaneuveringunit
    SHANG Yi-Fan, KANG Zhi-Yu1, ZHANG Qing-Zhan,YANG Dong-Chun
    2016, 36 (3):  85-94.  doi: 10.16708/j.cnki.1000-758X.2016.0033
    Abstract ( 983 )   PDF (5229KB) ( 908 )   Save
    MannedmaneuveringunitsmadebyAmericanandtheSovietUnionbothusetwosetsofindependentpropulsionsystems,whicharebackupforeachother.Thebackuppropulsionsystemcantaketheplaceofthefailurepropulsionsystem,buttherearenofurthersafeguardsforthebackupsystem.Thetraditionalschemerestrictsthesafetyandextravehicularability.Basedontheconventionalpropulsionmodeanemergencypropulsionmodewasproposed.Differentstrategieswerecarriedoutaccordingtothepositionalrelationshipofthefailuredthrusters.Theremainingeffectivethrusterstoensurethe6-DOFcontrolwerecombined.Calculationandsimulationresultsindicatethat,theemergencypropulsioncancompletethetaskofextravehicularactivitieswithreductionofpropulsion,andtheschemeisfeasible.
    Related Articles | Metrics