Dictionary
Instrumental drift
…VIM (JCGM 200:2012) 4.21 Instruments
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25 results for “Instrumental drift”
Dictionary
Stability of a measuring instrument
The property of an instrument whereby its metrological properties remain constant in time — quantified by the time taken to drift a stated amount, or…
…Measurementsshowedthatthelaserbeamwavelengthexhibitedfastfluctuationandslow drift.Fastfluctuationwillcausenoise-likeeffectsonthemeasurement.However,the magnitudeofwavelength fastfluctuation islessthan0.003%,whichcausedasimilar changeinbeamwidthmagnitudethatcanbeignored.Theslowdriftofthewavelength willcauseadifferencebetweenresultsofNISTandDUTmeasurementsandadifference betweenNISTmeasurements beforeandafterthetestmetermeasurementsduetothe timedifferenceofthemeasurements.Testresultsshowedthatwavelength driftcouldbe ashighas0.01%whenthelaserisoperatedinconstantcurrentmode,whichconvertsto anestimatedstandarduncertaintyinbeamwidthmeasurementof0…
Dictionary
Check standard
A stable artifact or instrument measured regularly within a measurement assurance program; its control chart reveals drift, shifts, or loss of statistical control of…
…Thisisfortunatelytrueforeachofthe thermalconvertersused.Afteraninitialwarm-up peiiodofaminuteorso,themaximumobscrvfni driftunderthoselaboratoryconditionsofanyoftiie thermalconverterstestedwaslessthan0.5percent perhour,andtheaveragelessthan0.05percentper hour. Ifitwerenecessary,theeffectofsignificant driftcouldbepracticallyeliminatedbyusingadeflec- tionmethodasoutlinedfortransfertests,calibrating thestandardinstrumentondirectcurrentatthe nominallycorrectcuncntorvoltagebeforeandafter eacha-csetting. Forac-<lcdifferenceortransfertests…
Documents
SOP 4 — Double Substitution
…drift in the measurement process. The double substitution procedure is the same for all weighing instruments , but the adjustment of the weighing instrument to…
…Theapparatusinvolvedinourinternalqualitycontrolsystemincludevoltage standards, voltagemeasuring instruments, resistancemeasuring instruments, standardplatinumresistancethermometers, calibratedreferencethermocouples, thermocouple checkstandards, andvariousthermometric fixed-points. The maintenanceandcalibrations oftheseapparatusarediscussedinthefollowing subsections . 4.1VoltageStandards IntheNISTthermocouplecalibrationlaboratories sinceelectromotive forceis measured, itisessentialtomaintaindcvoltagestandardscalibratedinterms…
…E.Uncertainties 1.Instrumental Bias BecauseofthespecialdesignoftheRTS,thecombinedsystematicerror introducedbythespectrophotometer itselfintomeasurements ofthetrue regulartransmittance definedinSectionII.Ahasbeenminimized. The individualcomponentsofthiserrorarediscussed inReference[1]andare heresummarized asfollows. Beam-displacement anddefocusingeffects: Theseareundetectable…
Documents
SOP 49 — Cal Env Stds
…If excess drift is suspected or observed in either the instruments or the environment, use two sets of observations in reverse order (S 1…
…For calibration purposes, humidity instruments chain to temperature and pressure realizations — the CCT's domain — through humidity generators and chilled-mirror hygrometers. The library…