DIN 2444-1972 钢管上的锌镀层.安装用钢管热镀锌的质量标准

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【英文标准名称】:StandardTestMethodforCalibratingandMeausringCTDensity
【原文标准名称】:校准和测量计算机断层摄影密度的标准试验方法
【标准号】:ASTME1935-1997(2008)
【标准状态】:现行
【国别】:美国
【发布日期】:1997
【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】:E07.01
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:computedtomography;contrastsensitivity;CTdensityresolution;densitycalibration;linearattenuationcoefficient;massattenuationcoefficient;Computedtomography(CT);Contrastmanipulation/sensitivity;CTdensityresolution;Linearattenuatio
【摘要】:ThistestmethodallowsspecificationofthedensitycalibrationprocedurestobeusedtocalibrateandperformmaterialdensitymeasurementsusingCTimagedata.Suchmeasurementscanbeusedtoevaluateparts,characterizeaparticularsystem,orcomparedifferentsystems,providedthatobservedvariationsaredominatedbytruechangesinobjectdensityratherthanbyimageartifacts.ThespecifiedproceduremayalsobeusedtodeterminetheeffectiveX-rayenergyofaCTsystem.TherecommendedtestmethodismoreaccurateandlesssusceptibletoerrorsthanalternativeCT-basedapproaches,becauseittakesintoaccounttheeffectiveenergyoftheCTsystemandtheenergy-dependenteffectsoftheX-rayattenuationprocess.This(orany)testmethodformeasuringdensityisvalidonlytotheextentthatobservedCT-numbervariationsarereflectiveoftruechangesinobjectdensityratherthanimageartifacts.Artifactsarealwayspresentatsomelevelandcanmasqueradeasdensityvariations.Beamhardeningartifactsareparticularlydetrimental.Itistheresponsibilityoftheusertodetermineorestablish,orboth,thevalidityofthedensitymeasurements;thatis,theyareperformedinregionsoftheimagewhicharenotoverlyinfluencedbyartifacts.Linearattenuationandmassattenuationmaybemeasuredinvariousways.Foradiscussionofattenuationandattenuationmeasurement,seeGuideE1441andPracticeE1570.FIG.1DensityCalibrationPhantom1.1ThistestmethodcoversinstructionfordeterminingthedensitycalibrationofX-andx03B3;-raycomputedtomography(CT)systemsandforusingthisinformationtomeasurematerialdensitiesfromCTimages.ThecalibrationisbasedonanexaminationoftheCTimageofadiskofmaterialwithembeddedspecimensofknowncompositionanddensity.ThemeasuredmeanCTvaluesoftheknownstandardsaredeterminedfromananalysisoftheimage,andtheirlinearattenuationcoefficientsaredeterminedbymultiplyingtheirmeasuredphysicaldensitybytheirpublishedmassattenuationcoefficient.Thedensitycalibrationisperformedbyapplyingalinearregressiontothedata.Oncecalibrated,thelinearattenuationcoefficientofanunknownfeatureinanimagecanbemeasuredfromadeterminationofitsmeanCTvalue.Itsdensitycanthenbeextractedfromaknowledgeofitsmassattenuationcoefficient,oronerepresentativeofthefeature.1.2CTprovidesanexcellentmethodofnondestructivelymeasuringdensityvariations,whichwouldbeverydifficulttoquantifyotherwise.Densityisinherentlyavolumetricpropertyofmatter.Asthemeasurementvolumeshrinks,localmaterialinhomogeneitiesbecomemoreimportant;andmeasuredvalueswillbegintovaryaboutthebulkdensityvalueofthematerial.1.3AllvaluesarestatedinSIunits.1.4Thisstandarddoesnotpurporttoaddressthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:C43
【国际标准分类号】:35_240_80
【页数】:5P.;A4
【正文语种】:英语


【英文标准名称】:FlexibleMaterialsInterconnectConstructions
【原文标准名称】:挠性材料互连结构
【标准号】:ANSI/UL796F-2005
【标准状态】:作废
【国别】:美国
【发布日期】:2005
【实施或试行日期】:
【发布单位】:美国国家标准学会(ANSI)
【起草单位】:ANSI
【标准类型】:()
【标准水平】:()
【中文主题词】:覆层材料;电导体;柔性;柔性材料;绝缘板材;内联结构;多层印制电路板;印制电路;印制导线;印制电路板;刚性
【英文主题词】:Coatingmaterials;Electricconductor;Flexible;Flexiblematerials;Insulatingplates;Interconnectionstructures;Multilayerprintedboards;Printedcircuits;Printedwiring;Printed-circuitboards;Rigid
【摘要】:
【中国标准分类号】:J04
【国际标准分类号】:31_180
【页数】:
【正文语种】:英语