Sensitivity of blackbody effective emissivity to wavelength and temperature: By genetic algorithm
- National Metrology Institute of South Africa (NMISA), Private Bag X34, Lynnwood Ridge, Pretoria, 0040 (South Africa)
A variable-temperature blackbody (VTBB) is used to calibrate an infrared radiation thermometer (pyrometer). The effective emissivity (ε{sub eff}) of a VTBB is dependent on temperature and wavelength other than the geometry of the VTBB. In the calibration process the effective emissivity is often assumed to be constant within the wavelength and temperature range. There are practical situations where the sensitivity of the effective emissivity needs to be known and correction has to be applied. We present a method using a genetic algorithm to investigate the sensitivity of the effective emissivity to wavelength and temperature variation. Two matlab® programs are generated: the first to model the radiance temperature calculation and the second to connect the model to the genetic algorithm optimization toolbox. The effective emissivity parameter is taken as a chromosome and optimized at each wavelength and temperature point. The difference between the contact temperature (reading from a platinum resistance thermometer or liquid in glass thermometer) and radiance temperature (calculated from the ε{sub eff} values) is used as an objective function where merit values are calculated and best fit ε{sub eff} values selected. The best fit ε{sub eff} values obtained as a solution show how sensitive they are to temperature and wavelength parameter variation. Uncertainty components that arise from wavelength and temperature variation are determined based on the sensitivity analysis. Numerical examples are considered for illustration.
- OSTI ID:
- 22218042
- Journal Information:
- AIP Conference Proceedings, Vol. 1552, Issue 1; Conference: 9. international temperature symposium, Los Angeles, CA (United States), 19-23 Mar 2012; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ALGORITHMS
BLACKBODY RADIATION
CALIBRATION
CORRECTIONS
EMISSIVITY
GLASS
INFRARED RADIATION
LIQUIDS
MATHEMATICAL SOLUTIONS
PLATINUM
PYROMETERS
SENSITIVITY ANALYSIS
TEMPERATURE DEPENDENCE
TEMPERATURE MEASUREMENT
THERMOMETERS
VARIATIONS
WAVELENGTHS