Moisture evaluation by dynamic thermography data modeling
- ITEF-CNR, Padova (Italy)
This paper is the prosecution of previous works on the design of a Non Destructive method for in situ detection of moistened areas in buildings and the evaluation of the water content in porous materials by thermographic analysis. The use of heat transfer model to interpret data allows to improve the measurement accuracy taking into account the actual boundary conditions. The relative increase of computation time is balanced by the additional advantage to optimize the testing procedure of different objects simulating the heat transfer. Two models are tested both analytically and experimentally: (1) the semi-infinite body to evaluate the thermal inertia and water content; (2) the slab to measure the sample`s diffusivity, the dependence of conductivity with the water content and to correct the water content estimation. The fitting of the experimental data on the model is carried out according to the least square method that is linear in the first case and nonlinear in the second. The Levenberg-Marquardt procedure is followed in nonlinear fitting to search in the parameters space the optimum point that minimizes the Chi-square estimator. Experimental results on bricks used in building for restoration activities, are discussed. The water content measured in different hygrometric conditions is compared with known values. A correction on the absorptivity coefficient dependent on water content is introduced.
- OSTI ID:
- 220709
- Report Number(s):
- CONF-940449-; ISBN 0-8194-1549-9; TRN: IM9620%%103
- Resource Relation:
- Conference: Society of Photo-Optical Instrumentation Engineers conference on intelligent information systems, Orlando, FL (United States), 4-8 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of Thermosense 16: An international conference on thermal sensing and imaging diagnostic applications; Snell, J.R. Jr. [ed.]; PB: 330 p.; Proceedings/SPIE, Volume 2245
- Country of Publication:
- United States
- Language:
- English
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