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Determining directional emissivity: Numerical estimation and experimental validation by using infrared thermography |
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| Institution: | 1. University of Antwerp, Op3Mech, Salesianenlaan 90, B-2660 Antwerp, Belgium;2. Vrije Universiteit Brussel, Acoustics & Vibration Research Group, Pleinlaan 2, B-1050 Brussels, Belgium;3. University of Antwerp, Laboratory of Biomedical Physics, Groenenborgerlaan 171, B-2020 Antwerp, Belgium;1. School of Electrical Engineering, and Tianjin Key Laboratory for Control Theory & Applications in Complicated Systems, Tianjin University of Technology, Tianjin 300384, China;2. Department of Telecommunications, Brno University of Technology, 61200 Brno, Czech Republic;1. Materno-fetal and Obstetrics Research Unit, Department “Femme-Mère-Enfant”, University Hospital, 1011 Lausanne, Switzerland;2. Swiss Teratogen Information Service, University Hospital, 1011 Lausanne, Switzerland;3. Division of Clinical Pharmacology, University Hospital, 1011 Lausanne, Switzerland;4. Institute of Microbiology, Faculty of Biology and Medicine, University of Lausanne and University Hospital, Lausanne, Switzerland;5. School of Pharmaceutical Sciences, University of Geneva and Lausanne, Geneva, Switzerland;6. Department of Epidemiology, Harvard School of Public HEalth, Boston, MA, USA;7. Unit of Emerging Infectious Diseases, Institut Louis Malardé, Tahiti, French Polynesia |
| Abstract: | Little research has examined that inaccurate estimations of directional emissivity form a major challenge during both passive and active thermographic measurements. Especially with the increasing use of complex curved shapes and the growing precision of thermal cameras, these errors limit the accuracy of the thermal measurements. In this work we developed a technique to estimate the directional emissivity using updated numerical simulations. The reradiation on concave surfaces is examined by thermal imaging of a homogeneous heated curved metal and nylon test sample. We used finite element modelling to predict the reradiation of concave structures in order to calculate the parameters of an approximating formula for the emissivity dependent on the angle to the normal vector on each element. The differences between experimental and numerical results of the steel test sample are explained using electron microscopy imaging and the validation on different materials. The results suggest that it is possible to determine the errors of thermal imaging testing of complex shapes using a numerical model. |
| Keywords: | Thermal imaging Emissivity Finite element modelling Thermography Inverse problem |
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