Time filter

Source Type

Marrakchi O.C.,Institute National Des Science Appliquees Et Of Technology Of Tunis
Teledetection | Year: 2012

In this paper, several methods have been tested for the analysis of natural textures extracted from remote sensing imagery with totally different acquisition mode. We have to propose, according to the nature of the texture, an optimal method that allows to identify it, characterize it by textural signatures, and analyze it at the same time. Texture windows were taken from an air borne radar SAR image with a resolution of 4,6 mandan ASTER sensor image of the satellite TERRA with a resolution of 15m. Despite the strong correlation of the texture of each image, we have shown that one of the methods for instance the analysis by the co-occurrence matrix (GLCM), through the transformation in principals components (ACI), the transformation of Karhunen Loeve (TKL) or the transformation in wavelets (TO) can be an effective way to describe the texture perfectly. Through these methods, we achieved rates of identification of textures all above 92% for all textures. © Revue Télédétection.

Hosni F.,Center National des science et Technology Nucleaires | Farah K.,Center National des science et Technology Nucleaires | Farah K.,University of Sousse | Mejri A.,Center National des science et Technology Nucleaires | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

The present paper reports the results of the study on the effect of the fractionation dose on the response of Red-Perspex dosimeter. Several experiments were carried out by combining the two factors: number of fractionation and storage time between fractions. Dosimeters were irradiated by gamma-rays to total doses of 10 and 40 kGy. These doses were delivered as single fraction, as well as in five fractions separated by different intervals of time: 1, 24 h and stored at 10 or 40 °C between successive irradiation. Three batches of Red-Perspex dosimeters (KS, GB, and EB) were used in this study. The relative specific response of dosimeters indicates a marked dependence of the number of fractionation and storage time. It was found that response variations due to dose fractionation can reach 18% in particular at high storage time and high temperatures. The dose fractionation effect has been found to be dependent of the batches. The obtained results allowed us to determine the necessary corrections for estimating doses with high accuracy.

Rachdi L.T.,Departement de Mathematiques | Msehli N.,Institute National Des Science Appliquees Et Of Technology Of Tunis
Acta Mathematica Scientia | Year: 2012

Using reproducing kernels for Hilbert spaces, we give best approximation for Weierstrass transform associated with spherical mean operator. Also, estimates of extremal functions are checked. © 2012 Wuhan Institute of Physics and Mathematics.

Discover hidden collaborations