Sensitivity of different methods for simultaneous evaluation of emissivity and temperature through multispectral infrared thermography simulation

International audienc

Penser, classer au Mundaneum

Le Mundaneum a rouvert ses portes au mois de juin à Mons (Belgique), à l\u27occasion de Mons 2015, capitale européenne de la culture. Voici maintenant rassemblé pour la première fois depuis très longtemps ce qu\u27il reste de l\u27ensemble des collections constituées par Henri La Fontaine et Paul Otlet, ces bibliographes utopistes, pour réaliser à l\u27orée du XXe s. ce projet tentaculaire d\u27un « internet de papier »

Feature-based tracking of urethral motion in low-resolution trans-perineal ultrasound

This paper describes a novel algorithm for tracking the motion of the urethra from trans-perineal ultrasound. Our work is based on the structure-from-motion paradigm and therefore handles well structures with ill-defined and partially missing boundaries. The proposed approach is particularly well-suited for video sequences of low resolution and variable levels of blurriness introduced by anatomical motion of variable speed. Our tracking method identifies feature points on a frame by frame basis using the SURF detector/descriptor. Inter-frame correspondence is achieved using nearest-neighbor matching in the feature space. The motion is estimated using a non-linear bi-quadratic model, which adequately describes the deformable motion of the urethra. Experimental results are promising and show that our algorithm performs well when compared to manual tracking

Infrared Thermography in Civil Engineering: From Non Destructive Testing in Laboratory to Outdoor Thermal Monitoring

International audienceBeing able to perform full field easily noninvasive diagnostics for surveillance and monitoring of transport infrastructures and structures is a major preoccupation of many technical offices. Among all the existing electromagnetic methods, active infrared thermography [1] up to long-term thermal monitoring using uncooled infrared cameras is a promising technique [2]. Anyway, except for vision applications [3], there is few results available in literature (mainly on buildings) for outdoor measurements by infrared thermography. So, to complete, a review of specificities and constraints for in situ measurements on large scale structures is proposed. Key points identified are analyzed versus infrared system technological potential solutions available on the shelf or at laboratory level. To introduce transfer from laboratory conditions to real field, we will lean on some laboratory works on active thermography applied to quality control of reinforcement operations by gluing composite (CFRP) plates or tissues on concrete structure [4] or voids in pavement [5]. First, we will introduce and discuss the benefit of using numerical heat transfer modeling to optimize the control process [6,7] or generate virtual thermal image sequences to test post-processing methods [8_,9]. It will be followed by presentation and discussion on experiments carried out using laboratory specimen. Then, some post-processing analysis approaches will be discussed. Finally, considerations on requirements to move from laboratory conditions to real site field measurements will be proposed. Following the laboratory level presentation, a review of various experiments carried out, with an adapted infrared system, on different transport infrastructures or large scale element of Civil Engineering structures in outdoor conditions is given [10,11]. Raw results analysis is proposed. Processed data, obtained from few thermal images [12] to few days of experiments [10-11,13] up to several month of experiments, are presented and discussed. Lessons learned from in situ outdoor experiments are then addressed. In particular, field expertise acquired was used to initiate the development of a new infrared system architecture " Cloud2IR " dedicated to long term monitoring [14]. An overview of this new architecture is proposed and discussed. In particular, benefit of using standards for measured data, but not only, is addressed. Finally, a summary of results obtained and current limitations of studied solutions [15] is given. Perspectives in term of in-situ inspection solutions by active infrared thermography (i.e. under natural solicitations) or by coupling techniques [16] are proposed

Keynote by Jean Dumoulin Title : Real site thermal monitoring of transport infrastructures and structures by infrared thermography

International audienceBeing able to perform easily noninvasive diagnostics for surveillance and monitoring of transport infrastructures and structures is a major preoccupation of many technical offices. Among all the existing electromagnetic methods, long-term thermal monitoring by uncooled infrared cameras is a promising technique due to its dissemination potential according to its low cost on the market. The talk will address the study, the development and the implementation of adapted IR measurement systems for the thermal monitoring of transport infrastructures or buildings in outdoor conditions. The survey of environmental parameters during measurements will be addressed and discussed. Some examples of experiments carried out on real large scale structures will be presented and analyzed. Finally, discussion on the interoperability of such system, models for analysis and observed limitations will be presented and completed by perspectives

Identification of thermal properties distribution in building wall using infrared thermography

International audienceIn the construction sector, most of the measurements carried out from IR camera devices are exploited in a qualitative way (e.g. observation of thermal bridges). However, unless a quantitative analysis is realized, it is not possible to assess the impact of the observed phenomena. Most of research efforts and proposed solutions to identify quantified thermal properties (e.g. U-values) have to be completed, adapted to the built environment and validated in experimental and real conditions to allow quantified assessment of materials thermal properties thanks to IR camera devices [1]. We still need several steps in terms of scientific and technical developments for such technological progress. The H2020 European Built2Spec research project (http://built2spec-project.eu/) aims at giving highlights on that. Heat transfer through the walls are generally model by 1D heat equation in the wall depth. The built is composed by a multilayer domain representing the construction process. In this context, the thermal parameters of the wall are piecewise constant space functions. We propose a methodology to recover the vector of the wall thermal properties (conductivity and capacity) from boundary measurements obtained from an IR camera. It formulates as an inverse problem where the unknown are sought as minimizers of a cost function evaluating the gap between the measures and the model response. This optimization problem is non linear, and we solve it with the Levenberg-Marquardt algorithm coupled with the conjugate gradient method [2-3]. To shorten the time of the identification process, we use the adjoint method coming from the control theory [4]. This method fasten the gradient computation by solving an associated model, named the adjoint model. We study the ability of the procedure to reconstruct internal wall constitution from different environmental conditions. Furthermore, we propose a controlled experimental test to evaluate the method in laboratory conditions. References [1] L. Ibos, J-P. Monchau, V. Feuillet, Y. Candau, A comparative study of in-situ measurement methods of a building wall thermal resistance using infrared thermography, i

Infrared Thermography applied to transport infrastructures monitoring: outcomes and perspectives

International audienceLong term monitoring of transport infrastructures by infrared thermography has been studied and tested on different structures. A first standalone infrared system architecture developed is presented and discussed. Results obtained with such system on different Civil Engineering structures are presented. Some data processing approaches and inverse thermal model for data analysis are introduced and discussed. Lessons learned from experiments carried out in outdoor with such system are listed and analyzed. Then, a new generation of infrared system architecture is proposed. Finally, conclusions and perspectives are addressed