基本信息
| 标准名称： | 水处理药剂 异噻唑啉酮衍生物 |
| 英文名称： | Water treatment chemicals -- Isothiazolone derivative |
| 中标分类： |
化工 >>
化学助剂、表面活性剂、催化剂、水处理剂 >>
水处理剂 |
| ICS分类： |
化工技术 >>
化工产品 >>
水净化用化学试剂
|
| 替代情况： | SH 2604.09-1997 |
| 发布日期： | 2003-11-29 |
| 实施日期： | 2004-01-01 |
| 首发日期： | |
| 作废日期： | |
| 出版日期： | |
| 页数： | 6页 |
适用范围
没有内容
前言
没有内容
目录
没有内容
引用标准
没有内容
所属分类： 化工 化学助剂 表面活性剂 催化剂 水处理剂 水处理剂 化工技术 化工产品 水净化用化学试剂
【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