学科分类
/ 1
3 个结果
  • 简介:Inthisstudy,thesampledatawasbasedon2190branchlengthandanglesamplesof30treesfromdahurianlarch(Larixgmeiinii)plantationslocatedinWuyingForestBureauinHeilongjiangProvince.Thestepwiseregressiontechniqueswereusedtodevelopbranchlengthandbranchanglemodels:BL=b1+b2DINC+b3DINC2+b4DBH·DINC2,BA=b1+b2DINC+b3DINC2+b4DBH·DINC.Then,thedevelopedmodelswerefittedusinglinearmixed-effectsmodelingapproachbasedonLMEprocedureofS-PLUSsoftware.Evaluationstatistics,suchasAIC,BIC,LogLikelihoodandLikelihoodratiotestwereusedformodelcomparisons.Theresultsshowedthatthebranchlengthandbranchanglemodelswithparametersb1,b2,b3asmixedeffectsshowedthebestperformance.Exponentialandpowerfunctionswereincorporatedintomixedbranchlengthandbranchanglemodel.Theadditionoftheexponentialandpowerfunctionssignificantlyimprovedthemixed-effectsmodel.Theplotsofstandardizedresidualsindicatedthatthemixed-effectmodelwithexponentialandpowerfunctionsshowedmorehomogeneousresidualvariancethanthemixed-effectsmodel.Validationconfirmedthatthemixedmodelwithcalibrationofrandomparameterscouldprovidemoreaccurateandpreciseprediction.Therefore,theapplicationofmixedmodelnotonlyshowedthemeantrendsofbranchlengthandbranchangle,butalsoshowedtheindividualdifferencebasedonvariance-covariancestructure.

  • 标签: branch LENGTH branch ANGLE LINEAR MIXED
  • 简介:MODIS(中等决定成像分光辐射函数)是在地(曙光女神AM)和水(曙光女神下午)上的一台关键仪器卫星。线性光谱混合模型为陆地封面的亚象素分类被用于MOIDS数据。在中国的浙江省的Shaoxing县被选择是学习地点,早米饭作为学习庄稼被选择。从MODIS象素使用的陆地封面的导出的比例线性光谱混合模型与从在一样的天获得的TM数据导出的无指导的分类相比,它暗示MODIS数据能为米饭耕作被用作卫星数据来源区域评价,可能米饭生长在地区性的规模上监视并且产量预报。

  • 标签: 水稻 种植区域 线性光谱混合剂 中等分变成像分光辐射度计
  • 简介:Basedonamultilevellinearmixedmodelapproach,anindividualdiameterincrementmodelwasdevelopedforfirplantationtreesgrowinginJiangxiProvince.Thedatasetusedinthisstudycamefromlong-termpermanentresearchplots.Thedatabaseconsistsoftotalof82counties,365plots,5416treesand16248observations.Thepaperchosemixedeffectsmodelsinsteadofregressionanalysisapproachbecauseitallowsforpropertreatmentoferrortermsandcorrelationinarepeatedmeasuresanalysisframework.Themodelwasdefinedasamixedlinearmodelwithparameterrandomeffectofplot,areaorplotandareasimultaneous.Inadditiontheheteroscedasticityandcorrelationwastakenintoaccount.Mixedmodelcalibrationofdiameterincrementwascarriedoutwiththeindependentdatausingadifferentsampleofcomplementaryobservations.Theresultshowedthatthetotalstandbasalarea,thediameteroftargettrees,theratioofbasalareaoflargertreestotargettreediameter,andaltitudewerefoundtobesignificantpredictors.Boththefittingmodelandthecalibratedmodelmeanasubstantialimprovementcomparedwiththeclassicalapproachwidelyusedinforestmanagement.Aftertakingintoaccountreasonablevariancefunctionofheteroscedasticityandcorrelation,themodelshowsbetterofgoodnessoffitthanonlytakingintoaccountparameterrandomeffects.Thistypeofmodelingmethodologyshowsflexible,preciseandaccurate.

  • 标签: INDIVIDUAL diameter INCREMENT HETEROSCEDASTICITY correlation structure