فهرست مطالب j. vahidi

Digital images watermarking is a method for data hiding that ensures the security of multimedia data. In these ways, a watermark can be a digital image or data stored within digital content. The Shearlet transform, a multi-resolution and multi-directional conversion, can be used for watermarking in digital images. Due to its superior features, this conversion can increase the efficiency of applications such as watermarking of images. In this paper, Shearlet and SVD transforms are used with the Whale optimization algorithm to obtain the most appropriate scaling factor in the watermark extraction step after applying different types of image processing attacks. Shearlet Transform has more transparency than traditional converts. The SVD transform also increases the robustness of watermarking operations. The results of different experiments show that the new method presented in this paper, in terms of robustness and imperceptibility compared to the methods tested, performs better than most image processing attacks.

In this paper, we solve Hamilton-Jocobi-Bellman (HJB) equations arising in optimal control problemsusing Homotopy Perturbation Transform Method (HPTM). The proposed method is a combined formof the Laplace Transformation Method with the Homotopy Perturbation Method to produce a highlyeffective method to handle many problems. Applying the HPTM, solution procedure becomes easier,simpler and more straightforward. Some illustrative examples are given to demonstrate the simplicityand efficiency of the proposed method.

In this article, Ritz approximation have been employed to obtain the numerical solutions of a class of the fractional optimal control problems based on the Caputo fractional derivative. Using polynomial basis functions, we obtain a system of nonlinear algebraic equations. This nonlinear system of equation is solved and the coefficients of basis polynomial are derived. The convergence of the numerical solution is investigated. Some numerical examples are presented which illustrate the theoretical results and the performance of the method.