Sharif Digital Repository

We propose a method for steganalysis of still, grayscale images using a novel set of features that are extracted from images. This feature set employs the Gabor filter coefficients to train a multi-layer perceptron neural network and a support vector machine classifier. We show that incorporation of the Gabor filter coefficients to the feature sets of images could have a significant role in discrimination between clean and altered images. Experimental results show that the proposed method outperforms previous methods, introduced for steganalysis of LSB-matching image steganography, in terms of both discrimination accuracy and feature set dimensionality. © 2009 IEEE  

The root-MUSIC algorithm is a popular method to estimate Angle of Arrival (AoA) as an extension of multiple signal classification (MUSIC). In this paper, we have proposed a novel solution for the root-MUSIC algorithm. The new method exhibits a much lower computational complexity, while maintaining the same theoretical performance as the root-MUSIC. © 2019 IEEE  

In this paper, we propose an improved timing estimation method for orthogonal frequency division multiplexing (OFDM) systems. The proposed preamble-aided method is independent of the preamble structure and is based on taking advantage of the whole products available from a given preamble for its correlation. Capable of having an extended correlation length far beyond those used by the previous methods, the proposed scheme presents an estimator with a remarkable performance in severe noise conditions. Further, we introduce a reduced complexity estimator along with the complexity assessments. We finally evaluate the performance of the proposed method in terms of mean square error (MSE). The... 

Reducing the computational complexity as well as convergence time is the main task of adaptive antenna array processing. This article proposes an improved algorithm for estimating the weights of adaptive array elements based on Constant Modulus Algorithm (CMA). In this new type of algorithm, those weights that have higher effect on the radiation pattern will be estimated and antenna pattern will be adjusted by changing these weights. In this research, 3 new algorithms are proposed. By simulating these algorithms and comparing them with conventional full weight CMA, finally new algorithm that has a reduced complexity and an acceptable performance at different signal to noise ratios (SNRs) is... 

Adaptive scheduling schemes which consider channel conditions are examples of cross-layer design in wireless networks. Research work which has been done on optimizing the performance of scheduling systems have shown that in each time slot it is better to transmit to the users with the best channel condition. In order to realize such schemes, most of earlier works have considered perfect feedback channels to send Channel State Information (CSI) to the scheduler. However, in practical systems there are some sources of imperfectness in feedback channels such as delay and quantization error. In this paper, we consider the effect of CSI delay on the performance of such systems. A new delay-aware... 

Observatory-scale data collection efforts allow unprecedented opportunities for integrative, multidisciplinary investigations in large, complex watersheds, which can affect management decisions and policy. Through the National Science Foundation-funded REACH (REsilience under Accelerated CHange) project, in collaboration with the Intensively Managed Landscapes-Critical Zone Observatory, we have collected a series of multidisciplinary data sets throughout the Minnesota River Basin in south-central Minnesota, USA, a 43,400-km2 tributary to the Upper Mississippi River. Postglacial incision within the Minnesota River valley created an erosional landscape highly responsive to hydrologic change,...