Development and validation of a numerical tool for the simulation of the temperature field and infrared radiance rendering in an urban scene

International audienceWe present a numerical tool aimed at simulating infrared images of an urban environment, by solving the direct heat transfer problem, and then computing the radiance rendering at the sensor level. SOLENE (Cerma, Nantes) was coupled with two software packages developed at ONERA: SUSHI (Simulation in Urban Scene of Heat dIffusion) and MOHICANS (MOdélisation Hyperspectrale d'Images en entrée Capteur pour l'ANalyse et l'inversion du Signal) for realizing this task. SUSHI is also used for computing the surface temperatures: either a 1D model or a 2D model is used. We present the whole software chain, its validation by software and experimental analysis

Lumber moisture evaluation by a reflective cavity photothermal technique

Photothermal methods constitute a convenient approach for the nondestructive quality control of industrial materials because they are rapid and noninvasive. One such application is the monitoring of moisture in unseasoned lumber for drying mill process control. This paper describes a photothermal method for the analysis of moisture in wood by measuring its surface temperature rise under laser radiation. It is shown that this parameter is much more sensitive than thermal diffusivity to moisture content variations. A reflective cavity technique is used to increase both the absorptivity and the emissivity of the inspected surface in order to improve the measurement reliability. Results obtained with an off-center hemispherical cavity on wood samples of different moisture content are presented and discussed

Lumber moisture evaluation by a reflective cavity photothermal technique

Photothermal methods constitute a convenient approach for the nondestructive quality control of industrial materials because they are rapid and noninvasive. One such application is the monitoring of moisture in unseasoned lumber for drying mill process control. This paper describes a photothermal method for the analysis of moisture in wood by measuring its surface temperature rise under laser radiation. It is shown that this parameter is much more sensitive than thermal diffusivity to moisture content variations. A reflective cavity technique is used to increase both the absorptivity and the emissivity of the inspected surface in order to improve the measurement reliability. Results obtained with an off-center hemispherical cavity on wood samples of different moisture content are presented and discussed.Les méthodes photothermiques constituent une approche pratique pour le contrôle non destructif de la qualité des matériaux industriels car elles sont rapides et non intrusives. Une de ces applications concerne la mesure de l'humidité pour le contrôle du procédé de séchage du bois. Cet article décrit une méthode photothermique pour l'évaluation du degré d'humidité dans le bois humide à partir de l'évolution thermique de la surface sous irradiation laser. On montre ici que l'effusivité thermique est beaucoup plus sensible que la diffusivité thermique aux variations du contenu d'humidité. Une cavité réfléchissante est utilisée afin d'accroître l'absorptivité ainsi que l'émissivité effectives de la surface inspectée de façon à augmenter la fiabilité des mesures. On présente et on discute les résultats obtenus avec une cavité hémisphérique décentrée sur des échantillons en bois à différents contenus d'humidité

Diffusivity measurement by using a grid-like mask

Communication to : Journee SFT thermographie quantitative, Chatillon (France), March 31, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1999 n.73 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Combined laser spot imaging thermography and ultrasonic measurements for crack detection

A surface crack, close to a small, well-defined heated spot, impedes lateral heat flow and produces alterations in the shape of the thermal spot image that can be monitored by thermography. Spot heating has been achieved using both cw and pulsed laser beam illumination on stainless steel and titanium samples and the technique has been found to be successful for determining the location of fatigue cracks. When using a pulsed laser beam one can also simultaneously generate wideband ultrasonic signals in the sample; this can be used to detect the presence of surface and sub-surface defects in the sample. Results are presented that have been obtained using a fixed camera and cw laser beam position with the sample being moved through the field of view of the camera. Results are also presented using a fixed camera and sample, with a raster scanned cw or pulsed lasers beam moving across the sample. A demonstration of how a non-contact ultrasonic measurement can be performed simultaneously is presented. Thermal imaging results obtained using cw laser beam heating close to a surface crack are compared with predictions made using a preliminary 2D numerical model

Inversion method for effusivity depth profile retrieval Application to characterisation of case hardened steel

Communication to : Workshop on advanced infrared technology and applications, Venice (Italy), September 28-30, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2000 n.21 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Simultaneaous measurement of in-plane and out-of-plane diffusivity by using a grid-like mask

Communication to : Workshop on advanced infrared technology and applications, Venice (Italy), September 28-30, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2000 n.44 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Deconvolution of thermography images obtained on corroded parts by using the thermal modulation transfer function (TMTF)

Communication to : 4th international workshop on advances in signal processing for non destructive evaluation of materials, Quebec (Canada), August 07-10, 2001Available from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2001 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Technique d'inversion pour la determination d'un profil d'effusivite a partir d'un thermogramme de surface transitoire

Communication to : Congres francais de thermique - SFT 2000, Lyon (France), 15-17 mai 2000SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2000 n.100 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

A non-destructive thermal method for indirect evaluation of in-depth hardness profile in case-hardened steel

Communication to : ATTT 2000 - 1er congres europeen de traitement thermique, Metz (France), 14-16 juin 2000SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2000 n.139 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc