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简介：Inthispaper,ahybridadaptivecompensationcontrolschemeisproposedtocompensatethefrictionoccurrenceandothernonlineardisturbancefactorsthatexistinthehigh-precisionservosystem.Anadaptivecompensationcontrollerwithadual-observerstructureisdesigned,whiletheLuGredynamicfrictionmodelwithnon-uniformparametricuncertaintiescharacterizesthefrictiontorque.Consideringtheinfluenceoftheperiodicdisturbancetorqueandparametricuncertainties,fuzzysystemsandarobusttermareemployed.Inthisway,thewholesystemcanbetreatedasasimplelinearmodelafterbeingcompensated,thentheproportional-derivative(PD)controllawisappliedtoenhancingthecontrolperformance.OnthebasisofLyapunovstabilitytheory,theglobalstabilityandtheasymptoticconvergenceofthetrackingerrorareproved.Numericalsimulationsdemonstratethattheproposedschemehaspotentialstorestraintheimpactofdisturbanceandimprovingthetrackingperfor

简介：Inthepasttwentyyears,theproportionofcoalinprimary-energyconsumptioninChinaisgenerallybetween71.3%and76.5%.Theoutputofcoalwas1.374billiontonsin19%,and1.21tonsin1998,whichrankedfirstintheworld.NowcoalisminedmainlywithmechanizationinChina,whichisplannedtoreach80%inmajorState-ownedcoalminesin2000accordingtotheplanningofthegovernment(Lietal.,1998;TangDejin,1998).ComparedwiththeUSAandAustralia,Chinahasmorecomplexcoalgeologicalstructures.Basedonhigh-resolutionseismictechniqueincoalexploration,anewseismictechniquewithhigh-precisionandhigh-resolution(2-Dand3-D)hasbeendevelopedforthepurposeofdetectingsmallgeologicalstructuresincoalmineconstructionandproductiontomeettheneedsoflarge-scalepopularizationofmechanizedcoalmininginChina.Thetechniqueislowincostandrequiresarelativelyshortperiodofexploration,withhighprecisionandwide-rangeapplications.Inthemiddleoft

简介：Inthispaper,thespectralelementmethod(SEM)isimprovedtosolvethemovingloadproblem.Inthismethod,astructurewithuniformgeometryandmaterialpropertiesisconsideredasaspectralelement,whichmeansthattheelementnumberandthedegreeoffreedomcanbereducedsignificantly.BasedonthevariationalmethodandtheLaplacetransformtheory,thespectralstiffnessmatrixandtheequivalentnodalforceofthebeam-columnelementareestablished.ThestaticGreenfunctionisemployedtodeducetheimprovedfunction.Theproposedmethodisappliedtotwotypicalengineeringpractices—theone-spanbridgeandthehorizontaljibofthetowercrane.Theresultshaverevealedthefollowing.First,thenewmethodcanyieldextremelyhigh-precisionresultsofthedynamicdeflection,thebendingmomentandtheshearforceinthemovingloadproblem.Inmostcases,therelativeerrorsaresmallerthan1%.Second,bycomparingwiththefiniteelementmethod,onecanobtainthehighlyaccurateresultsusingtheimprovedSEMwithsmallerelementnumbers.Moreover,themethodcanbewidelyusedforstaticallydeterminateaswellasstaticallyindeterminatestructures.Third,thedynamicdeflectionofthetwin-liftjibdecreaseswiththeincreaseinthemovingloadspeed,whereasthecurvatureofthedeflectionincreases.Finally,thedynamicdeflection,thebendingmomentandtheshearforceofthejibwillallincreaseasthemagnitudeofthemovingloadincreases.

简介：同位素在在地球科学跟踪并且标明日期起一个重要作用，特别87Rb-86Sr系统。与地球科学的发展，整个岩石的分析斜面足够地满足要求因为科学研究和微量分析变得越来越重要。激光脱离多收集者诱导地联合的血浆mass-spectrometry(LA-MC-ICP-MS)广泛地由于它的低样品消费在微地区的分析被使用了，高精确性在矩阵上的situ和低要求，但是当它被严重优秀辨别和集体光谱干扰的各种各样的类型限制，精确地与高Rb/Sr比率和低Sr内容特别为样品测量Sr同位素作文仍然是困难的。因而，热电离mass-spectrometry(提姆)分析同位素的比率的最精确、精确的方法，仍然是分析Sr比率的最流行的方法，特别为有低Sr内容的样品。这篇论文在low-Sr的高精确的Sr同位素分析上做系统的评论地质的样品包括微采样的技术，极端低的程序的空白的化学方法和提姆测量技术。极端低的程序的空白和提姆的联合能被用来与ng大小执行样品的高精确的微量分析，它将无疑是为Rb-Sr地球年代学，地球化学和环境研究的一个重要方向。

简介：Ahigh-precisionwavelengthcontrollerispresentedinthispaper.ItisnecessarytofindoutthedifferencebetweenthecentralwavelengthofatunablefiberFabry-Perot(FFP)filterandthatoftheinputlaser,whilethewavelengthcontrol-leroperatesatthestatesofwavelength-scanningandwavelength-lockingmodes.Firstly,adynamicsimulationmodeloftunableFFPfilterisestablished,andthedynamiccharacteristicoftunableFFPfiltermodulatedbyanalternatingcurrent(AC)signalissimulated.Thenthemeasuringtimeatwavelength-scanningmodecomparedwiththetheorytimeisdiscussed,andthistimedifferenceshowsthedifferencebetweenthecentralwavelengthofatunableFFPfilterandthatoftheinputlaser.Atlast,theeffectsonwavelength-lockingprecisionoftimedelays,includingthetimedelayofopened-loopcircuit,thetimeconstantoftheclosed-loopcircuitandtheintrinsichysteresisofpiezoelectric(PZT)element,areanalyzed.AwavelengthcontrolleroftunableFFPfilterisdesignedandprepared.Theexperimentalresultsatwavelength-lockingmodeshowthatahighlockingprecisionisobtained.

简介：Thefeasibilityofmoni-toringthechangeofcitysettlementusingGPSsurveyinginsteadoflevel-ingisstudied.AfiducialnetworkandamonitoringnetworkareestablishedinNingbocity.TwoperiodsofGPSobservationarecompleted.Somemeasuresaretakenduringtheobser-vationinordertoensuretoobtainthehigh-preciseheightcomponent.TheSaastamoinenmodelisadoptedinthedataprocessingofthedrycomponentpartofthetroposphericdelay.Thewetcomponentchangeofthetropo-sphericdelayisestimatedbystochasticprocessesmodel.WhenBernesesoft-wareisusedtoprocessthedata,themillimeterlevelprecisionofheightmeasuringisachieved.

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简介：Timesynchronizationtechniques,especiallyonthepulsepersecond(PPS)temporalbasis,haveattractedgrowingresearchinterestsinrecentyears.Inthispaper,wehaveproposedandexperimentallydemonstratedahigh-precisiontwo-waytimetransfer(TWTT)systemtorealizelong-distancedisseminationof1PPSsignalgeneratedbyahydrogenmaser.Adense-wavelength-division-multiplexing(DWDM)systemandbi-directionalerbium-dopedfiberamplifiers(Bi-EDFAs)havealsobeenadoptedtosuppresstheimpactofRayleighbackscatteringandoptimizethesignaltonoiseratio(SNR)aswell.Wehavetheoreticallyanalyzedthesystematicdelayindetail.Theultimaterootmeansquare(RMS)variationoftimesynchronizationaccuracyissub-26psandthetimedeviationcanbereducedtoaslowas1.2psat100sand0.253psat12000s,respectively.

简介：Thegroup-delaydispersionofanopticalfiberwasmeasuredwiththetime-of-flightmethod,usingfingerprint-likecharacteristicspectrafromamode-lockedfiberlasersource.Todeterminethegroup-delaydispersionuptothefourthorder,least-squaresfittingwasappliedtotheoveralltimewaveformmappedonthetimeaxisforthefingerprint-spectralbroadbandpulsesthroughalongopticalfiber.Theanalysisofall4003datapointsreducedstatisticaluncertainty,andprovidedsecond-,third-,andfourth-orderdispersionwithuncertaintiesof0.02%,0.4%,and4%,respectively.

简介：挑战性的微型卫星收费载重的精确轨道决心(捣烂)卫星基于位置和在武汉大学里被开发的航行数据分析家(熊猫)软件被做，用从白天126～131的年2002的机载的GPS数据。Theorbit精确性被从GFZprocessed以后科学轨道(PSO)分析差别估计，GPS搬运人和伪范围数据剩余和变化的卫星激光(SLR)剩余。

简介：WiththehelpofCCDimages,therealizationofhighprecisionpo-sitioningandmeasurementhasbecomethebasicstandardformachinevisionandrealtimephotogrammetrysystems.However,deformationandothersortsofdegradationoccurringduringtransmissionaremajorlimitingfactorsofthepreci-sionattainablewithmostcurrentCCDcamerasandframegrabbers.SoapreciseradiometricandgeometrictransmissionofimagesfromCCDsensortomemoryisafundamentalaspectofCCDcameracalibration.Thegeometriccalibrationsystem,whichusessomeimageprocessingalgorithmsoftheCCDcamerabasedonthere-searchedanddevelopedsystemisdiscussed.Thereliabilityandvalidityarealsodiscussed.TheexperimentalresultsforthecalibrationoftheCCDarraywillbetakenasanimportantqualityindexforCCDevaluation.

简介：ＯＮＴＨＥＨＩＧＨＰＲＥＣＩＳＩＯＮＡＤＡＰＴＩＶＥＯＰＥＮＢＯＵＮＤＡＲＹＣＯＮＤＩＴＩＯＮＳＦＯＲＴＲＡＮＳＩＥＮＴＷＡＶＥＳ￥ＺｏｕＧｕａｎｇ－ｙｕａｎ（Ｄｅｐｔ．ｏｆＭｅｃｈａｎｉｃｓａｎｄＥｎｇｉｎｅｅｒｉｎｇＳｃｉｅｎｃｅｓ，Ｐｅｋｉｎｇ...

简介：Inthispaper,theoperationprincipleoflaserrotaryencodersisexpoundedandtheopticalquadruplefrequencytechnologyusedinlaserrotaryencodersinex-plained,andthedesignideaofopticalsysteminΦ66mmlaserrotaryencoderismainlyintroduced,aswellasthechoiceofprincipaldevices.

简介：Theexactanalyticmethodwasgivenby[1].Itcanbeusedforarbitraryvariablecoefficientdifferentialequationsandthesolutionobtainedcanhavethesecondorderconvergentprecision.Inthispaper,anewhighprecisionalgorithmisgivenbasedon[1],throughabendingproblemofvariablecross-sectionbeams.Itcanhavethefourthconvergentprecisionwithoutincreasingcomputationwork.Thepresentcomputationmethodisnotonlysimplebutalsofast.Thenumericalexamplesaregivenattheendofthispaperwhichindicatethatthehighconvergentprecisioncanbeobtainedusingonlyafewelements.Thecorrectnessofthetheoryinthispaperisconfirmed.

简介：有EDM的GPS和高精确的距离测量的联合网络的一个新解决方案被建议。同时，它“s不妥当的仅仅使用的GPS网络与甩开大小。三个计划：陆上的网络，GPS网络和联合网络被讨论因为鉴于精确，Xiangjiaba的平面控制网设计建水坝，可靠性，详细协调并且支付。

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简介：Thestabilityofsubmarinegeologicalstructureshasacrucialinfluenceontheconstructionofoffshoreengineeringprojectsandtheexploitationofseabedresources.Marinegeologistsshouldpossessadetailedunderstandingofcommonsubmarinegeologicalhazards.Currentmarineseismicexplorationmethodsarebasedonthemosteffectivedetectiontechnologies.Therefore,currentresearchfocusesonimprovingtheresolutionandprecisionofshallowstratumstructuredetectionmethods.Inthisarticle,thefeasibilityofshallowseismicstructureimagingisassessedbybuildingacomplexmodel,anddifferencesbetweentheseismicinterferometryimagingmethodandthetraditionalimagingmethodarediscussed.Theimagingeffectofthemodelisbetterforshallowlayersthanfordeeplayersbecausecoherentnoiseproducedbythismethodcanresultinanunsatisfactoryimagingeffectfordeeplayers.Theseismicinterferencemethodhascertainadvantagesforgeologicalstructuralimagingofshallowsubmarinestrata,whichindicatescontinuoushorizontalevents,ahighresolution,aclearfault,andanobviousstructureboundary.TheeffectsoftheactualdataappliedtotheShenhuareacanfullyillustratetheadvantagesofthemethod.Thus,thismethodhasthepotentialtoprovidenewinsightsforshallowsubmarinestrataimaginginthearea.

简介：ＰｒｅｌｉｍｉｎａｒｙｒｅｓｕｌｔｓｏｎｋｉｎｅｍａｔｉｃｍｏｄｅｌｏｆｔｅｃｔｏｎｉｃｂｌｏｃｋｓｄｅｒｉｖｅｄｆｒｏｍｈｉｇｈｐｒｅｃｉｓｉｏｎＧＰＳｏｂｓｅｒｖａｔｉｏｎｓｉｎＳｏｕｔｈｗｅｓｔＣｈｉｎａＬＩＲＥＮＨＵＡＮＧ１）（黄立人）...