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【英文标准名称】:StandardPracticeforSamplingForestTreesforDeterminationofClearWoodProperties
【原文标准名称】:测定无疵病木材性能用林森书面的标准抽样规范
【标准号】:ASTMD5536-1994(2010)
【标准状态】:现行
【国别】:美国
【发布日期】:1994
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:D07.08
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:
【英文主题词】:clearwood;forest;foresttrees;sampling;Timber;Trees;Clearwoodevaluation/testing;Cruciformsampling;Forestland;Randomsampling;Samplingwoodproducts
【摘要】:Thispracticecoversproceduresofsamplingforobtainingsmallclearwoodspecimenswhich,whentestedinaccordancewithMethodsD143and,inconjunctionwithfull-sizeproducttests,willprovidemechanicalpropertiesforuseinderivingdesignpropertiesforlumber,panels,poles,houselogs,andotherproducts.Dataobtainedbytestingspecimenssampledinaccordancewiththesemethodsalsoprovideinformationontheinfluenceonmechanicalpropertiesofsuchfactorsasdensity,localityofgrowth,positionincrosssection,heightinthetree,andmoisturecontent.Cruciformsamplingisofprincipalvaluewheninformationisdesiredontheinfluenceonmechanicalpropertiesofheightinthetree;ofageorradialpositioninthetree;ofrateofgrowth;thechangefromsapwoodtoheartwood;therelationshipsbetweenmechanicalpropertiesandfactorssuchasspecificgravity;andmakinggeneralcomparisonsbetweenspeciesforpurposesofratingorselectingspeciesforspecificend-useproducts.Cruciformsamplingdoesnotprovideunbiasedestimatesofmeanvalues,percentileorotherdescriptivestatistics,orameansofassociatingstatisticalconfidencewithestimatesofdescriptivestatistics.Doublesamplingisusedwhenitisdesiredtoimproveorupdateexistingestimatesofmechanicalpropertyvaluesthatarethebasisforestablishingallowabledesignstressesforstress-gradedlumber,plywood,polesandpiling,andotherwoodproducts.Themethodinvolvespredictingonepropertybycarefullyobservingawell-correlatedauxiliarypropertythatispresumablyeasierorcheapertomeasure.Asampleestimateoftheauxiliarypropertyisobtainedwithahighdegreeofprecisionbyrepresentativelysamplingthepopulation.Asmallerindependentsampleorasubsampleofthelargesampleisusedtoestablisharelationshipbetweentheauxiliarypropertyandthepropertyforwhichanestimateisdesired.Asappliedtosamplingaforest,doublesamplinghasemployedspecificgravitytopredictmechanicalproperties.Thedouble-samplingmethodprovidesunbiasedestimatesofmeanmechanicalpropertyvaluesandanapproximationmethodforestimatingpercentilevalues.Statisticalconfidencemaybeassociatedwiththeestimatesofthemeansbutnotthepercentilevalues.Randomsamplingisusedwhenprobabilityestimatesofdescriptivestatisticsandpropertydistributionalcharacteristicsaredesiredasthebasisforestablishingallowabledesignstressesforlumberandotherstress-ratedproducts.Itisapplicablewhendataforaspeciesdonotexistorwhenexistingestimatesarebelievednolongerapplicablebecauseofachangingforestcharacter.Randomsamplingprovidesbetterprobabilityestimatesthandoublesamplingandislessexpensiveandquickerifsamplingandtestingmustbecompletedtoestablishmechanicalproperty-specificgravityregressionsforthedouble-samplingmethod.1.1Thispracticeofferstwoalternativephysicalsamplingprocedures:cruciformsamplingandrandomsampling.Thechoiceofprocedurewilldependupontheintendeduseforthetestresults,theresourcesavailableforsamplingandtesting,andtheavailabilityofexistingdataonthemechanicalpropertiesandspecificgravityofthespeciesofinterest.1.2Athirdprocedure,doublesampling,isincludedprimarilybyreference.Thisprocedureappliestheresultsofcruciformorrandomsamplesthroughcorrelationtoimproveorupdatepropertyvalues.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:B69
【国际标准分类号】:
【页数】:9P.;A4
【正文语种】:英语