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25 April 2012, Volume 32 Issue 2 Previous Issue    Next Issue

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Method of Autonomous Celestial Navigation Based on UKF and Information Fusion LUO Nan, XU Lu-Ping, ZHANG Hua 2012, 32 (2):  1-9.  doi: 10.3780/j.issn.1000-758X.2012.02.001 Abstract ( 2282 )   PDF (568KB) ( 1869 )   Save  X -ray pulsars navigation uses the time of arrival (TOA) of the X-ray pulse radiation to resolve the position. Star sensor based navigation uses the angle between line of sight to the star and the center of earth to resolve the position. The mechanisms of the two navigation systems are different from each other. An information fusion celestial utonomous navigation method was proposed by hybriding the pulsars TOA and elevation angle of star sensor measurement. And the simulation experiments based on unscented Kalman filter (UKF) using real orbit parameters were carried out. A hard-in-loop simulation system which uses the laser quantum to emulate the X-ray quantum of pulsars was designed to test the method. The results show that, comparing to the methods based on pulsars or star sensor only, the estimation accuracy of position and velocity of the proposed method can increase 52.7%, 43.6%, 82.2% and 70.5% respectively, and its performance is better than extended Kalman filter (EKF) information fusion method. Related Articles | Metrics

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BudgetAnalysisandSimulationofInter-satelliteLinkinWalker-δConstellation HAN Song-Hui, GUI Qing-Ming, LI Jian-Wen, DU Yuan-Lu 2012, 32 (2):  10-16.  doi: 10.3780/j.issn.1000-758X.2012.02.002 Abstract ( 2758 )   PDF (449KB) ( 1503 )   Save There is a need for more discussion on the other transmission loss and a reasonable transmission power of inter-satellite link (ISL). Firstly, the criteriafor ISL establishment were given under the agreement of short average distance and small range of ISL azimuth, elevation angleanddistance.Secondly,  the budget of the ISL, the free spacepropagationlossandothertransmissionlosswerediscussed,andthereferencevalueor the formulaofthesetransmissionlosseswasgivenlater.Furthermore,areasonabletransmissionpowerwas given bythe probabilisticknowledgeundertheconditionthatthemathematicalexpectationofthepracticaldatawasequaltotherateddataofthetransferrate.Then,thevarianceformulaofthedatatransmissionratewasderived.Finally,therangesofazimuth,elevationangleanddistanceofISLintheWalker27/3/1constellationwereanalyzedbysimulation.Theimpactofdifferentcarrierfrequenciesanddataratesonthetransmissionpowerwerediscussed,andareasonabletransmissionpowerwasalsodetermined. Related Articles | Metrics

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Research on CO2 Adsorption Characteristics of Hydrophobic ZSM-5 Adsorbent WANG Xi-Qin, LI Kai, LUAN Zhi-Qiang, YE Ping-Wei 2012, 32 (2):  17-21.  doi: 10.3780/j.issn.1000-758X.2012.02.003 Abstract ( 1958 )   PDF (292KB) ( 1700 )   Save ThetraditionalCO2removalmethodwith 5A zeolite molecular sieve will lose efficacy because of the strong affinity with the water vapor.Ahydrophobic ZSM-5 adsorbent was preparedbyamixtureofZSM5,silicasol,waterandadditives,followedbyprocessesofextrusion,dryingandthenhydrophobicmodification.Thestructuresandpropertiesoftheadsorbentwere analyzed by N2, H2O/CO2adsorptionisothermsandXRDanalysismethods.Thepreparedadsorbenthasmultilevelpore structure,highBETspecificsurfacearea(296m2/g) andbetterCO2adsorptionperformance,aswell asexcellenthydrophobicity, and the H2O equilibriumadsorptioncapacityisabout1% of weightevenundertheconditionof90%relativehumidity. Related Articles | Metrics

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AbsoluteErrorSelectionCriteriaofUnconstrainedModefor FlexibleManipulatorDynamicsModelDimensionReduction QI Nai-Ming, ZHAO Bao-Shan, ZHAO Zhi-Gang, WANG Li-Ping 2012, 32 (2):  22-28.  doi: 10.3780/j.issn.1000-758X.2012.02.004 Abstract ( 1855 )   PDF (347KB) ( 1574 )   Save Theunconstrainedmodedynamicsdimensionreductionmethodsonlyconsiderthestructuralparameterswithoutanalyzingtheimpactofthecontrolforce.DuetoanycontrolforcecanbeequivalenttothesuperpositionofaninfinitenumberofsinusoidalforcebyFourieranalysismethod,anunconstrainedmodeselectioncriteriaundersinusoidalforcebasedontheabsoluteerrorwaspresented.Theelasticdeformationofflexiblemanipulatorwasmodeledbyusingthefiniteelement(FE)method.ThedynamicsmodelofflexiblemanipulatorwasdeducedbyusingtheLagrangeapproach.Thesolutionofunconstrainedmodewasusedfordimensionreductionofthedynamicsequations.Thedimensionreductionofthedynamicsequationsandtheoriginaldynamicsequationswerecompared.Numericalsimulationsdemonstratethecorrectnessoftheproposedapproach. Related Articles | Metrics

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ConfigurationParameterAnalysisforADAM-typeArticulatedMast LI Biao, LIU Zhi-Quan, CHENG Gang, DING Feng 2012, 32 (2):  29-34.  doi: 10.3780/j.issn.1000-758X.2012.02.005 Abstract ( 2099 )   PDF (405KB) ( 1738 )   Save TheconfigurationofADAM-typearticulatedmastwasdescribed,andmain configuration parameterswerechosen. FiniteelementmodelsoftheADAM-typemastwerebuiltupbyANSYS.Usingthesemodels,modeanalysiswascarriedout.By comparingtheanalysisresultswithexperimentresults,thecorrectnessofthefiniteelementmodelswasvalidated.Theeffectsofbaylength,canisterradius,crosssectionsideandpreloadofthediagonalcablesontheperformanceofthemastwereanalyzed.Theanalysisresultsshowthattheperformancecanbeimprovedbyincreasingthebaylength.Thebendingstiffnessandmassofthemastwillbepromotedasthecanisterradiusincreases.Thepreloadsofthediagonalcablesshouldbeselectedbetweentheallowableminimumvalueandthevaluecorrespondingtothesituationwhentheballsocketsobtainmaximumstiffness.Theseconclusionscouldbeappliedinmastengineeringdesign. Related Articles | Metrics

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Space Target Recognition Based on Improved Kernel FCM WANG Xiao-Xue, YANG Yong-Sheng, JING Zhong-Liang 2012, 32 (2):  35-42.  doi: 10.3780/j.issn.1000-758X.2012.02.006 Abstract ( 2238 )   PDF (426KB) ( 1643 )   Save A recognitionsystemwaspresentedtoaccomplishspacetargetclassification.Firstly,Imagefeaturevectorswereextractedaccordingtoinvariantregionmoments,shapeandimagedescriptorsofspaceobjects.Andthen,clusteringalgorithmisappliedtotheclassifyspacetarget.AnimprovedkernelclusteringalgorithmbasedonVoronoidistancewasproposedwhichhadacrispermembershipfunctionandwasrobustfornoiseandoutliers.Experimentsshowthattheimprovedkernelfuzzyclusteringalgorithmismoreaccurateandvalidthanthatoftheconventionalmethods. Related Articles | Metrics

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StartupandOperatingCharacteristics ofCapillaryWickEvaporator LI Jin-Wang, ZOU Yong, CHENG Lin 2012, 32 (2):  43-47.  doi: 10.3780/j.issn.1000-758X.2012.02.007 Abstract ( 1923 )   PDF (336KB) ( 1628 )   Save Theeffectsofporouswickporosityandheatsourcepoweronstartupand operatingcharacteristicsofcapillarywick evaporator(justlikealoopheatpipewithoutlinkingthevaporline)wasinvestigated.Theexperimentwascarriedoutwithout mixingtheeffectoftheworkingfluidandthecondenser.Theresultshowsthatthetemperatureoftheevaporatorwill fluctuateinsomecasesduringthestartupofthesystem.Theheatsourcepowerwhichmakesthetemperaturefluctuated decreasinglywiththeincreasingporosityoftheporouswick.Whenporouswickisthesame,temperatureiseasierto fluctuateanditwillbemuchseriouswith the biggerheatsourcepower.Thereasonforthetemperaturefluctuationisthatthe porosity of porous wick does notmatchwiththeoutsideparameters,suchastheheatcoursepower. Related Articles | Metrics

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ConvolutiveBlindSeparationAlgorithmBasedonSatelliteCommunicationAnti-jamming WEN Yuan-Yuan, CHEN Hao 2012, 32 (2):  48-54.  doi: 10.3780/j.issn.1000-758X.2012.02.008 Abstract ( 1783 )   PDF (392KB) ( 1651 )   Save  Aimingattheproblemofsatellitecommunicationsignalandjammingblindseparationinnoisyenvironment,anewalgorithmforconvolutivemixtureblindsourceseparation (BSS)byexploitingthehouseholdertransformationtorealizethejointdiagonalizationofhighordercumulantandoperationinthefrequencydomainwasproposed.Comparedwiththeclassicalmethods,simulationresultsshowthattheproposedalgorithmhaslowercomputationalcomplexityandbetterseparationperformance.Whensignal to noiseratio (SNR)isgreaterthan10dB,thenovelalgorithmofanti-jammingcanrealizetheseparationofcommunicationsignalsandthejamming,andhasgoodseparationperformance. Related Articles | Metrics

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MultipleFaultDiagnosisAlgorithmUnderLargeFalse-alarmRateTests  ZHANG Sen, YU Deng-Yun, WANG Jiu-Long 2012, 32 (2):  55-61.  doi: 10.3780/j.issn.1000-758X.2012.02.009 Abstract ( 1932 )   PDF (440KB) ( 1312 )   Save  Multiplefaultdiagnosisunderunreliabletestsusingthemultisignalmodelwasstudied.TheoptimalmultiplefaultdiagnosisproblemisNPcomplete,sosuboptimalalgorithmwasusedforlargescalesystemdiagnosis.Agoodfaultestimationunderlowfalsepositiveratewasobtainedbythesubgradientoptimizationmethod.Butifthesizeofthegraphisbigandthefalsealarmrateishigh,thisalgorithmwill notbeabletoeliminatetheinfluenceoffalsepositive,andtheresultingestimationwouldcovereveryfailedtestinsteadoffindingthetruefaultpositionofthesystem.Anewkindofdiscriminatefunctionconsideringbothfalseandtruepositivetestswasused,andanimprovedgeneticalgorithmwasproposedtosearchthefailurecomponents.Simulationresultsshowthatthenewmethodisfasterthansubgradientoptimizationandhasahighercorrectisolationratewhenintercurrentfaultsarefew. Related Articles | Metrics

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Quasi-cycleLDPCConstructionMethod BasedonProtographExpansion  GONG Xian-Feng, TAO Xiao-Feng, QIU Le-De 2012, 32 (2):  62-67.  doi: 10.3780/j.issn.1000-758X.2012.02.010 Abstract ( 2739 )   PDF (334KB) ( 1809 )   Save Theperformanceoflowdensityparitycheckcode（LDPC）basedonprotopraphexpansiongreatlydependsontheexpansionmethod.AnewQC-LDPCconstructionmethodwasproposed.Twomainstepsintheparitycheckmatrixconstructionincludethemulti-edgeseliminationofprotographandquasi-cycleexpansion.Thefirststepmakelocalgirthmaximumundertheconstraintofedgepermutation.Inthesecondstep,optimumshiftvaluesofthepermutationmatriceswereobtainedbysearchingtheclosedloopswithinthespecifiedlengthandcomparingthelengthandapproximatecycleextrinsicmessagedegree(ACE)ofcycles,aimingatreducingsmallcycleswithlowconnectivitywhichwasharmfultothecodeperformance.Forprotographwithoutmulti-edges,theonlystepwasthequasicycleexpansion.Asprovedbysimulation,theconstructedQC-LDPChasexcellentperformanceinbothdecodingthresholdanderrorflooraspects. Related Articles | Metrics

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MultipleSpacecraftsOn-orbitServiceTaskAllocationBasedonDPSO ZHANG Qi-Xin, SUN Fu-Chun, XU Bin, LIU Hua-Ping 2012, 32 (2):  68-76.  doi: 10.3780/j.issn.1000-758X.2012.02.011 Abstract ( 2073 )   PDF (500KB) ( 1255 )   Save Inordertosolvemulticonstrainedon-orbitservicetaskallocationforspacecraft,theprogrammingofon-orbitservicetaskallocationforon-orbitsatelliteswasstudied.Basedontheanalysisofthekeyfactorsincludingtargetsatellitevalue,servicespacecraftlossandenergy-timeconsumption,anon-orbitservicingmulti-spacecrafttaskallocationmodelwasformulated.Adiscreteparticleswarmoptimization (DPSO) algorithmwasproposedforon-orbitservicespacecraftcooperativetaskallocationproblems.Anewparticlepositionandnewupdatestrategyfortheparticlespeedweredeveloped.ThesimulationresultsshowthattheproposedDPSOalgorithmadmitsbetterconvergence,optimizationcapability,andcansolvetheon-orbitservicespacecraftcooperativetaskallocationeffectively. Related Articles | Metrics

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CoordinatedManeuverofSpacecraftFormationBasedonLine-of-sightMeasurement  ZHANG Wei, FENG Xiao-Hui, DENG Zhong-Min 2012, 32 (2):  77-83.  doi: 10.3780/j.issn.1000-758X.2012.02.012 Abstract ( 1866 )   PDF (323KB) ( 1326 )   Save  Basedontheline-of-sightmeasurement,acooperativecontrolmethodforleaderlessformationflightispresented.Line-of-sightvectormeasurementisgeneratedwheneachsatelliteinaformationtracksitsneighboringspacecraft.Thefirstmemberoftheformationtracksthedesiredorbitaccordingtothecommandfromahighlevelcontroller.Achainformationisgenerated.Distancesbetweenline-of-sightmeasurementsaretakenasfeedbackoftheformationcontroller.Therelativeperturbationequationsareprovidedtomakesurethatmodelinguncertaintiesandperturbationsareconsideredinthecontrolstrategy.Cyclicformationcontrolisperformedviaslidingmodecontroller.Simulationresultsshowthattheproposedcontrolmethodcanbeusedforsatelliteformationmaintenanceandmaneuver. Related Articles | Metrics