Desenvolvimento de um algoritmo de processamento de dados radiométricos obtidos por termografia ativa pulsada

• Autor(a) principal: Silva, Wellington Francisco da
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: http://ri.ufs.br/jspui/handle/riufs/10995
• topic: Engenharia elétrica; Algoritmos computacionais; Calor; Processamento de imagens; Termografia ativa; Contraste máximo; Constante tempo; Compactação; Máximos temperatura; Active thermography; Maximum contrast; Time constant; Data compression; Maximum temperature; ENGENHARIAS::ENGENHARIA ELETRICA

This master thesis presents the development of an algorithm capable of detecting defects in materials, based on the technique of reconstruction of thermographic signals and the physical principles of heat transfer. As an experimental basis, tests performed and assigned by the Non-Destructive Testing, Corrosion and Welding Laboratory (LNDC) of UFRJ were used. Experimentally, a short thermal pulse is used and the surface temperature of the object is monitored over time through a thermographic camera. Due to the volume of data, the Ąrst step of the algorithm is data compression. Newton’s law of cooling was used as the basis of the phenomenon and a compression ratio of 99 % was obtained. The main contributions of the developed algorithm are: data compression and treatment of the heating data (which are neglected by the other techniques); use of the concept of change in the direction of the heat Ćow to delimit the edges of the regions of interest (Where the defects are probably located); edge detection/interface between the object and the image background; consolidation in a single image by aggregating the indicators referring to the concept of cooling/heating time constant, maximum temperature of each pixel and maximum contrast. Finally, as a result, a single image with all this information is presented, reducing the subjectivity of the operator and improving the effectiveness of this thermographic technique.