简介:AstochasticmodelfordailyprecipitationsimulationinChinawasdevelopedbasedontheframeworkofa′Richardson-type′weathergeneratorthatisanimportanttoolinstudyingimpactsofweather/climateonavarietyofsystemsincludingecosystemandriskassessment.ThepurposeofthisworkistodevelopaweathergeneratorforapplicationsinChina.Thefocusisonprecipitationsimulationsincedeterminationofotherweathervariablessuchastemperatureisdependentonprecipitationsimulation.AframeworkoffirstorderMarkovChainwithGammaDistributionfordailyprecipitationisadoptedinthiswork.Basedonthisframework,fourparametersofprecipitationsimulationforeachmonthat672stationsalloverChinaweredeterminedusingdailyprecipitationdatafrom1961to2000.Comparedwithpreviousworks,ourestimationfortheparameterswasmadeformorestationsandlongerobservations,whichmakestheweathergeneratormoreapplicableandreliable.Spatialdistributionsofthefourparametersareanalyzedinaregionalclimatecontext.Theseasonalvariationsoftheseparametersatfivestationsrepresentingregionaldifferencesarediscussed.Basedontheestimatedmonthlyparametersat672stations,dailyprecipitationsforanyperiodcanbesimulated.A30-yearsimulationwasmadeandcomparedwithobservationsduring1971-2000intermsofannualandmonthlystatistics.Theresultsaresatisfactory,whichdemonstratestheusefulnessoftheweathergenerator.
简介:本文通过甘 肃 宁 正 矿 区 地 形 航 测 工 程1:2 000地 形 图 项 目,以S86-T型号的RTK为例。阐述了GPS-RTK在地形测量的原理,并详细的介绍了RTK在测量中的优点及其技术不足和解决办法。 RTK技术在地形图图根测量、碎部测量中的操作方法和步骤及注意事项。并对影响RTK技术精度的因素进行分析。并详细的介绍了RTK在测量中的优点及其技术不足和解决办法。
简介:摘要 为满足一些五金件上的正三角形孔的低成本快速加工的需要,介绍了一种在普通铣床上利用行星轮法制作的钻孔装备。经过试验,加工效果良好,满足了生产的实际需求。