Approaches to the Moisture Content Monitoring Intimber Elements: Development of a Resistive Method

The scope of this work is based on the use of resistive method to quantify the water content in timber elements. For an in-depth mapping, we adapted a multiplexed technique derived from geophysics based on a maximum crossing of current lines to obtain topography of measures sweeping the space boundary conditions being defined by the sample. The calibration of these measures is completed by a gammadensimetry laboratory method which allows access to water profiles along a preferred direction. Nevertheless, the resistive method is penalized by logarithmic laws linking moisture and resistivity. So, we develop a hybrid method for coupling the data obtained to diffusion models: it will provide complementary information where resistivity and gammadensimetry are no longer effective. The developed experimental protocol allows employing the selected method and optimizing the diffusion properties (diffusion coefficient and convective exchange coefficient) injected into a characterization algorithm (Nelder-Mead’s simplex inversion method) based on a finite difference method for the Fick’s diffusion law determination integrating orthotropic and non- linear properties. Overlap between electric field and density measurements and the numerical simulation tool are possible.

MICROSTRUCTURE AND Jc OF YBCO SUPERCONDUCTOR PREPARED BY DIRECTION SOLIDIFICATION PROCESS

Polycrystalline YBCO superconductors have been prepared by a directional solidification process (DSP). X-ray diffraction pattern reveals the YBa 2Cu3 O 7−y phase of the samples possessing strong texture which grows out along the length of the tape-shape sample. This dense, regularly aligned, plate-shaped crystal structure is beneficial to transporting superconducting current according to the Jc measurement at 0–1 T and 77 K. Three basic defects and the reason for forming them are discussed. Jc values are measured by the standard four-probe dc resistive method at a criterion of 1 μv/cm. The optimum Jc values of DSP samples are over 12200 A/cm 2 and more than 4200 A/cm 2 at 77 K and 0–1 T respectively.