scholarly journals Temperature correction method for commercial CCD array spectrometers used in spectral radiometry measurement

2018 ◽  
Vol 972 ◽  
pp. 012020
Author(s):  
Ling Li ◽  
Caihong Dai ◽  
Zhifeng Wu ◽  
Yanfei Wang
Keyword(s):  
Correction Method ◽  
Temperature Correction ◽  
Ccd Array

scholarly journals A New High-Precision Correction Method of Temperature Distribution in Model Stellar Atmospheres

2013 ◽  
Vol 22 (2) ◽  
Author(s):  
A. Sapar ◽  
R. Poolamäe ◽  
L. Sapar
Keyword(s):  
Temperature Distribution ◽  
High Precision ◽  
Linear Optimization ◽  
Correction Method ◽  
Stellar Model ◽  
Temperature Correction ◽  
Stellar Atmospheres ◽  
Local Source ◽  
Plane Parallel ◽  
Iteration Loop

AbstractThe main features of the temperature correction methods, suggested and used in modeling of plane-parallel stellar atmospheres, are discussed. The main features of the new method are described. Derivation of the formulae for a version of the Unsöld-Lucy method, used by us in the SMART (Stellar Model Atmospheres and Radiative Transport) software for modeling stellar atmospheres, is presented. The method is based on a correction of the model temperature distribution based on minimizing differences of flux from its accepted constant value and on the requirement of the lack of its gradient, meaning that local source and sink terms of radiation must be equal. The final relative flux constancy obtainable by the method with the SMART code turned out to have the precision of the order of 0.5 %. Some of the rapidly converging iteration steps can be useful before starting the high-precision model correction. The corrections of both the flux value and of its gradient, like in Unsöld-Lucy method, are unavoidably needed to obtain high-precision flux constancy. A new temperature correction method to obtain high-precision flux constancy for plane-parallel LTE model stellar atmospheres is proposed and studied. The non-linear optimization is carried out by the least squares, in which the Levenberg-Marquardt correction method and thereafter additional correction by the Broyden iteration loop were applied. Small finite differences of temperature (

scholarly journals Comparison of GRUAN RS92 and RS41 Radiosonde Temperature Biases

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 857
Author(s):  
Xin Jing ◽  
Xi Shao ◽  
Tung-Chang Liu ◽  
Bin Zhang
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Lower Stratosphere ◽  
Correction Method ◽  
Temperature Correction ◽  
Pressure Level ◽  
Double Difference ◽  
Correction Algorithm ◽  
Warm Bias ◽  
Upper Troposphere

In this study, we validated the consistency of the GRUAN RS92 and RS41 datasets, versions EDT.1 and GDP.2, in the upper troposphere and lower stratosphere (200–20 hPa), through dual launch campaigns at the GRUAN site and using the radio occultation (RO) product and the ERA5 reanalysis from ECMWF as standards for double difference comparison. Separate comparisons with the references were also performed in order to trace the origin of the bias between the two instruments. Then, the performance of the GRUAN raw temperature correction algorithm was evaluated, from the aspects of day–night, the solar zenith angle, and the pressure level, for GDP.2 version products. The results show that RS92.EDT.1 has a warm bias of 0.355 K, compared to RS41.EDT.1, at 20 hPa, during daytime. This bias was found to mainly originate from RS92.EDT.1, based on the separate comparison with RO or ECMWF ERA5 data. RS92.GDP.2 is consistent with RS41.GDP.2, but a separate comparison indicated that the two original GDP.2 products have a ~1 K warm bias at 20 hPa during daytime, compared with RO or ECMWF ERA5 data. The GRUAN correction method can reduce the warm bias up to 0.5 K at 20 hPa during daytime. As a result, this GRUAN correction method is efficient, and it is dependent on the solar zenith angle and pressure level.

scholarly journals Enhancement of Imperfection Detection Capabilities in TIG Welding of the Infrared Monitoring System

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1624
Author(s):  
Jacek Górka ◽  
Wojciech Jamrozik
Keyword(s):  
Temporal Resolution ◽  
Low Cost ◽  
Decision Rules ◽  
Real Life ◽  
Correction Method ◽  
Industrial Applications ◽  
Absolute Temperature ◽  
Temperature Correction ◽  
Tig Welding ◽  
Infrared Monitoring

For a low cost, there are industrial infrared monitoring systems used for imperfection detection and identification in welded joints. The key drawback that impedes real life industrial applications is the low spatial resolution, as well as the temporal resolution of low-cost infrared (IR) cameras. This is also the case in tungsten inert gas (TIG) welding. Taking into consideration the influence of voltage on the arc energy and heat input, high frequency sampled voltage was used to evaluate the interpolated temporal resolution of IR sequences. Additionally, a reflected temperature correction method was proposed to reduce the uncertainty of absolute temperature measurement with a thermographic camera. The proposed method was applied to detect several imperfection types, such as lack of or incomplete penetration as well as incorrect weld shape and size (including burnouts). Results obtained for different interpolation factors were compared. The obtained results emphasize the validity of reflected temperature correction method. For the weld defects detection task, the smallest detectable defect was found for various interpolation factors. Moreover, the correspondence of arc voltage and the joint temperature was checked. Additionally, a set of decision rules was elaborated on and applied to distinguish between various joint conditions. It was found that defects that do not have symmetrical temperature distribution with respect to the joint axis are harder to identify.

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