Ali Khalfallah | Searcharxiv

arXiv2016

Image encryption with dynamic chaotic Look-Up Table

In this paper we propose a novel image encryption scheme. The proposed method is based on the chaos theory. Our cryptosystem uses the chaos theory to define a dynamic chaotic Look-Up Table (LUT) to compute the new value of the current pixel to cipher. Applying this process on each pixel of the plain image, we generate the encrypted image. The results of different experimental tests, such as Key space analysis, Information Entropy and Histogram analysis, show that the proposed encryption image scheme seems to be protected against various attacks. A comparison between the plain and encrypted image, in terms of correlation coefficient, proves that the plain image is very different from the encrypted one.

cs.CR↗

arXiv2014

A new Watermarking Technique for Medical Image using Hierarchical Encryption

In recent years, characterized by the innovation of technology and the digital revolution, the field of media has become important. The transfer and exchange of multimedia data and duplication have become major concerns of researchers. Consequently, protecting copyrights and ensuring service safety is needed. Cryptography has a specific role, is to protect secret files against unauthorized access. In this paper, a hierarchical cryptosystem algorithm based on Logistic Map chaotic systems is proposed. The results show that the proposed method improves the security of the image. Experimental results on a database of 200 medical images show that the proposed method significantly gives better results.

cs.MM↗

arXiv2014

Identification des lois de comportement des tôles à partir des essais de gonflement hydraulique

The paper describes a new method for the identification of the flow stress curves of anisotropic sheet metals using a hydraulic bulge tests through circular and elliptical dies. This method is based on analytical model using the membrane equilibrium equation and experimental data involving the measurement of only polar deflection and applied hydraulic pressure. Four hydraulic bulge tests are used for the identification of flow stress parameters and anisotropy coefficients of Hill48 yield criterion. A sensitivity analysis of material parameters is carried out by FEA of hydraulic bulge tests. This identification procedure is applied on low carbon steel DC04 used for sheet metal forming. The obtained results are used for numerical simulation of plane tensile test to validation the proposed method. It is shown a good agreement between predicted and experimental results. -- Le papier présente une nouvelle méthode pour l'identification des lois de comportement des tôles minces anisotropes à partir des essais de gonflement hydraulique en utilisant les essais à matrices circulaires et elliptiques. Cette méthode est basée sur un modèle analytique utilisant la théorie des membranes et des mesures expérimentales correspondants à la hauteur au pôle en fonction de la pression hydraulique appliquée. Quatre essais de gonflement hydraulique sont utilisés pour l'identification de la courbe d'écrouissage et les coefficients d'anisotropie du critère de Hill48. Une étude de sensibilité des paramètres matériels sur les réponses des essais de gonflement hydraulique (pression, hauteur et épaisseur au pole) pour les quatre essais est menée par simulation numérique par éléments finis. Cette méthodologie d'identification est appliquée à un acier doux DC04 destiné à l'emboutissage. Les résultats de l'identification obtenus sont utilisés pour simuler l'essai de traction plane. Il est démontré que les résultats trouvés sont en bon accord avec les réponses expérimentales.

cond-mat.mtrl-sci↗