简介:RequestedbyMinistryofCommerceofChinaandSASAC(State-ownedAssetsSupervisionandAdministrationCommissionoftheStateCouncil),thecreditevaluationofrefractoriesenterpriseswascarriedoutbyTheAssociationofChinaRefractoriesindustrybasedontheprincipleofopen,justice,andimpartiality.Thirtyoneenterpriseswere
简介:Neutralbeaminjectionisoneofthemainplasmaheatingmethodsinnuclearfusiondevices.InordertosupportthescientificstudyoftheExperimentalAdvancedSuperconductingTokamak(EAST),amegawatt-levelhighcurrentionsourceisdesignedandmanufacturedintheASIPP,andtheprogressandpreliminarytestresultswillbepresentedinthispaper.
简介:Radiointerference(RI),asanaftereffectofcoronadischarge,isanimportantresearchtopicinthefieldofelectromagneticcompatibility,whereexcitationfunctionisappliedbroadlytothepredictionofRIlevel.ThispaperpresentsthetheoryofexcitationfunctionmethodusedintheRIlevelprediction.Then,somepracticalproblemsrelatedtothismethodarediscussed.Thepropagationprocedureofcoronacurrentissolvedbythephase-modaltransformation,andtheimpedancematrixofmultitransmissionlinesiscalculatedbyadoublelogarithmicapproximatemodelofCarson'sGround-Returnimpedance.Atthesametime,inordertocalculatetheRIlevelwhentotallinecoronaisassumed,ananalyticalformulaisdeducedforintegraloperation.Basedontheabovesolutions,analgorithmispresentedandappliedtothepredictionofRIlevelofapracticaloverheadtransmissionline.Comparisonofpredictionandmeasurementresultsindicatesthatthealgorithmproposedinthispaperiseffectiveandfeasible.
简介:GroundlevelozonepollutionhasbecomeasignificantairpollutionprobleminBeijing.Becauseofthecomplexwayinwhichozoneisformed,itisdifficultforpolicymakerstoidentifyoptimalcontroloptionsonacost-effectivebasis.Thispaperidenti-fiesandassessesarangeofoptionsforaddressingthisproblem.WeapplytheAmbientLeastCostModelandcomparetheeco-nomiccostsofcontroloptions,thenrecommendthemosteffectivesequencetorealizepollutioncontrolatthelowestcost.ThestudyfindsthatinstallingofStageIIgasolinevaporrecoverysystematBeijing's1446gasolinestationswouldbethemostcost-effectiveoption.Overall,optionstoreduceozonepollutionbycuttingve-hicularemissionsaremuchmorecost-effectivethanoptionsto'cleanup'coal-firedpowerplants.
简介:ThispaperexaminesthelivelihoodchallengesexperiencedinRwanjabaLakeshoreCommunityduringtheperiodoflowwaterlevelinLakeVictoriabetween2004and2007andidentifiesthelivelihoodcopingstrategiesthatwereadoptedtoaddressthem.Atotalof55householdswererandomlysampledandthedatacollectionmethodsincludedhouseholdquestionnairesandparticipantobservations.ThedatawereanalyzedusingtheStatisticalPackageforSocialScience(SPSS)andtheresultspresentedwiththehelpofdescriptivestatistics.Thelivelihoodchallengesexperiencedduringthelowlakewaterlevelincludedfishshortage(34.5%),householdfoodscarcity(23.6%),sexforfish(18.2%),familybreakdown(12.7%),increasedtheft(7.2%)andaccidentsduetotheexposedrocksinthelake(3.6%).Thelivelihoodcopingstrategiesadoptedtoredressthechallengesincludedcausallabour(32.7%),maizeroasting(23.6%),sandmining(18.2%),sellingofsnacks(12.7%),sellinghouseholdproperty(9.1%)andresortingshopandmarketcredits(3.6%).Thepaperproposesanumberofrecommendationsforimprovingthelivelihoodofthecommunityrangingfrompolicyreformstothediversificationofactivities.
简介:Nonlinearmixedeffectsmodel(NLMEM)isbuiltontherelationshipofthefixedandrandomeffectsintheregressionfunction.TheNLMEMhasanobviouscomparativeadvantageinanalyzingthelongitudinaldata,repeatedmeasuresdataandmultileveldata.Two-levelNLMEMisusedtoanalyzethedominantheightforChinesefir(Cunninghamialanceolata).Theauthorsoutlinethetwo-levelNLMEMandintroducetheparametersestimationmethodofthemodel.BasedonfivecommonRichardandLogisticmodels,themixedmodelisbuilt.Themodelingdataareusedtocalculateandcomparewith19modelsderivedfromeachbasedmodel,and5optimalmixedmodelsarebuilt.Comparedthe5optimalmixedmodelswithtraditionalregressionmodels,itisshowedthatthetwo-levelNLMEMhasabetterfittingeffectthantheregressionmodel.
简介:Basedonamultilevellinearmixedmodelapproach,anindividualdiameterincrementmodelwasdevelopedforfirplantationtreesgrowinginJiangxiProvince.Thedatasetusedinthisstudycamefromlong-termpermanentresearchplots.Thedatabaseconsistsoftotalof82counties,365plots,5416treesand16248observations.Thepaperchosemixedeffectsmodelsinsteadofregressionanalysisapproachbecauseitallowsforpropertreatmentoferrortermsandcorrelationinarepeatedmeasuresanalysisframework.Themodelwasdefinedasamixedlinearmodelwithparameterrandomeffectofplot,areaorplotandareasimultaneous.Inadditiontheheteroscedasticityandcorrelationwastakenintoaccount.Mixedmodelcalibrationofdiameterincrementwascarriedoutwiththeindependentdatausingadifferentsampleofcomplementaryobservations.Theresultshowedthatthetotalstandbasalarea,thediameteroftargettrees,theratioofbasalareaoflargertreestotargettreediameter,andaltitudewerefoundtobesignificantpredictors.Boththefittingmodelandthecalibratedmodelmeanasubstantialimprovementcomparedwiththeclassicalapproachwidelyusedinforestmanagement.Aftertakingintoaccountreasonablevariancefunctionofheteroscedasticityandcorrelation,themodelshowsbetterofgoodnessoffitthanonlytakingintoaccountparameterrandomeffects.Thistypeofmodelingmethodologyshowsflexible,preciseandaccurate.