简介:<正>所谓3S技术即GPS、GIS、RS技术。GPS(全球定位系统)是英文缩写词NAVSTAR/GPS(NAVigationSystemTimeAndRanging/GlobalPositioningSystem)的简称。全称应为“测时测距导航系统/全球定位系统”。GPS是由美国研制,并投入实际应用的最新卫星定位系统。其主要目的是为飞机和船舶导航定位。也可以用于其它多种目的。GPS技术已在航空、航天、航海、军事、地质、石油、勘探、交通、测绘等领域得到广泛的应用。美国于1993年6月26日已将GPS21颗卫星和3颗备用卫星全部发射入轨。
简介:AppendixA:Thederivationofequation(4)InFourierdomain,d2(x)=2x2istransformatedintod2(kx)=-k2x(A1)Whenequation(3)isnumericalyc...
简介: Introduction Withrapiddevelopmentandadvancementofeconomyandsociety,lotsofcitygroupsorcitybeltswithex-tra-largecitiesastheircentershavebeenformedinChina.Theregionsthesecitygroupslieinusuallyhavewell-developedeconomy,densepopulation,andareregionalpoliticsandculturecenters.Somegroupslieintheregionswithhighlevelofearthquakeactivity,suchastheSurroundingCapitalCityGroupwiththecentersofBei-jingandTianjin.Oncealargeearthquakeoccurs,itsinfluencewillspreadtoveryextensiveregionanditsdisasterwillbetremendoustoo.Soearthquakeresistanceanddisastermitigationofcitygroupwillbeverysignificantissue.Thecitiesinagrouphaveclosedistancewitheachother;theycancarryoutunifiedpreparationfordisasterasonewholeandreducetheheavyloadofsinglecitybeforeanearthquake,andhaveanadvantageofpromptmutual-aidafteranearthquakebecauseofclosedistance.Itisespeciallysignificanttomitigatetheloseoflives.Oneimportantpreconditionisthatallthecitiesinonegroupcannotbeexposedtothesamelevelofdestroyduringoneearth-quake.Sothedivisionofcitygroupintheregionwithdensecitiesdistributionshallbeverysignificanttotheemergentmutual-aidinearlytimeafteralargeearthquake.Forthisgoal,thecharacteristicsandcorrelativityofearthquake′simpactoncitiesinonegroupneedtoclearlybeconsidered.Thecitieswithsimilarfeaturesandstrongcorrelativityofhistoricalearthquakeinfluencehavelargechancetosuffersameleveldestroyduringthefuturestrongearthquakeandaredisadvantagetoprovidemutual-aidandshallnotbedividedintoonegroup. ……
简介:ThestudiesonthestructureandphysicalpropertiesoftheEarth'sinteriordonebyChinesegeophysicistsfrom1999to2002werereviewedinthispaper.Itincludesseveralresearchareas:thestructureoftheEarth'sinteriorsusingseismictomography,anisotropyoftheuppermantleinChinaanditsadjacentareas,qualityfactorQβforSwaves,subductionzone,mantlediscontinuities,physicalpropertiesofEarth'smaterialsandothers.Thereviewconcernsmainlythecontents,themethodsandtheresultsofthestudies.ItcanbeseenthatnewprogressinthestudyonthestructureandphysicalpropertiesoftheEarth'sinteriorhasbeenmadeinthelast4yearsinChina.Itisshownonthreeaspects:advancementmadeonsomepreexistentareas;pioneeringonsomenewfieldsandnewmethodsadopted.
简介:TheanalysesoflighthydrocarbonsinoilsfromtheTarimBasinshowthattheMango'sparameterKisaboutunityexceptthoseoilstrappedintheeasternpartoftheTazhong(CentralTarim)FaultUplift,TheregularvarianceofKmayindicatestheaccumulationandadmixtureoftheoilpopulationsintheeasternpartoftheTazhongFaultUplift.
简介:First,Wirsching'smodel,whichiswidelyemployedinfatiguereliabilityanlysisofmarineandoffshorestructures,isanalysedsystematically.Itisfoundthattheveryimportantrandomvariable△inWirsching'smodelcannotbedirectlydeterminedfromfatigueexperimentbecauseoftheirreversibilityoffatiguetest,andinfact,whatWirschingstudiedfromtestingresultsisnot△butαofthestatisticalMiner'srule.Second,byuseofthestatisticalMiner'srule,amodifiedWirsching'smodelisproposed.Thirdlyandmoreimportantly,basedonthetwo-dimensionalprobabilisticMiner'srule,anewmodelisestablishedforfatiguereliabilityanalysisofstructuralcomponentssubjectedtospecifiedcyclicloadingofvariableamplitudeorstochastictimehistory.Intheend,anexampleispresented,fromwhichitwillbeseenthatthisnewmodelisveryconvenienttouseandfeasibletoengineeringpractice.
简介:TheimpactsofclimatechangeonChina'sagriculturearemeasuredbasedonRicardianmodel.Byusingcounty-levelcross-sectionaldataonagriculturalnetrevenue,climate,andothereconomicandgeographicaldatafor1275agriculture-dominatedcountiesintheperiodof1985-1991,wefindthatbothhighertemperatureandmoreprecipitationwillhaveoverallpositiveimpactonChina'sagriculture.However,theimpactsvaryseasonallyandregionally.Highertemperatureinallseasonsexceptspringincreasesagriculturalnetrevenuewhilemoreprecipitationisbeneficialinwinterbutisharmfulinsummer.Applyingthemodeltofiveclimatescenariosinthe2020sand2050sshowsthattheNorth,theNortheast,theNorthwest,andtheQinghai-TibetPlateauwouldalwaysbenefitfromclimatechangewhiletheSouthandtheSouthwestmaybenegativelyaffected.FortheEastandtheCentralChina,mostscenariosshowthattheymaybenefitfromclimatechange.Inconclusion,climatechangewouldbebeneficialtothewholeChina.
简介:BasedonChina’sobservationaldatain1951-1990,afterminimizingthepossiblebiasescausedbystationrelocationandurbanheatisland,thespatialandtemporaldistributionsoftrendsformaximumandminimumtemperaturesarestudied.Theresultsshowthatincreasingtrendsofmaximumtemperaturesareintheareaswestto95°E,andnorthtotheHuanghe(Yellow)River,whiledecreasingtrendsexistineasternChinasouthtotheYellowRiver.MinimumtemperaturesaregenerallyincreasingthroughoutChina,withdominantwarmingtrendsatthehigherlatitudes.Thisresultedinveryobviousdecreasingtrendsindiurnaltemperatureranges.Theperiodiccyclesareconsistentbetweenthemaximumandminimumtemperatures,butasymmetrictrendsareveryobvious.Thesignificantincreaseofminimum(nighttime)temperaturesreflectstheevidenceofenhancementofgreenhouseeffect.Furtheranalysisshowsthatthechangesofmaximumandminimumtemperaturesaremainlyrelatedtosunshinedurationandatmosphericwatervaporcontent.
简介:<正>ONSOUTHERNSTRETCHOPTHES-NTECTONICBELT,CHINAChenGuanghaoandWeiZhoulin(ChangshaInstituteofGeotectonic,AcademiaSinica,Changsha,410013,Hunan,China)S-Ntectonicbelt,southstretching,boundingbeltItcanbeinferredfromthegeophysicaldata,linearstructures,tectonicevolu-tionhistoryandmetallogenythattheS-NtectonicBeltstretchesfurthersouthinadifferentdi-rectionandmannerafterinterceptedbytheRedRiverFault,Thestretchingsegmentistheim-portanttectonicboundaryinIndo-AsiaandassiminlatestheS-Ntectonicbeltwithsomediffer-ences.
简介:选取三江平原典型沼泽湿地——毛苔草沼泽,通过人工施加氮肥和磷肥来模拟农田污水排入沼泽湿地后,沼泽植物对污水的净化效果。从植物营养吸收角度进行野外实地污水净化模拟研究,对植物直接吸收利用的营养成分NH4^+-N、PO4^3--P进行了测试分析。研究表明毛苔草沼泽对水中的NH4^+-N、PO4^3--P的净化随时间的推移呈现明显的指数衰减下降趋势,随着氮、磷含量的增加,沼泽湿地对污水净化逐渐变慢,净化所需时间增长,曲线数值方程模拟效果较好。
简介:ResearchonnonlinearR/SmethodanditspplicationinearthquakepredictionBi-QuanWANG(王碧泉);Han-MingHUANG(黄汉明);Hong-ShunFAN(范洪顺);Chuen...