Sharif Digital Repository

The goal of this thesis is using sparse decomposition to design secure steganography algorithms to insert secret data into the different cover signals. We propose data embedding in higher semantic levels of the cover signal to reach this goal. Sparse decomposition represents a signal as a linear combination of its structural elements. Data insertion into the sparse coefficients slightly changes the effect of structural elements in the signal representation. So, quality of the stego signal is preserved and such a steganography method leads to higher imperceptibility. In addition, data insertion into the higher semantic levels leads to the higher undetectability. Steganalyzers use statistical... 

Before performing any operation on a speech signal, it is necessary to properly remove the environmental noise existing on it. Noise Canceling Operation on Speech Signal is called speech enhancement. Up to now, many studies have been conducted on various ways to enhance the speech signal. Among the existing methods, statistical methods have proven to be superior to others. In all noise removal methods, the main challenge is that most noises are non-stationary. Since most of the noises in the environment are non-stationary, we are still looking for the better ways to remove them. With the advent of deep neural networks and their successful results in areas such as machine learning, a method... 

The use of functional electrical stimulation after spinal cord injury is one of the most effective ways to prevent muscle atrophy.” Enzymes construction set, torque output increases and improved fatigue resistance”.
Functional electrical stimulation devices help in the operation of a muscle by applying a weak electrical current. This stimulation causes muscle contraction. In other words, it replaces the neural signals required to move the limb that cannot be produced due to causes such as spinal cord injury (SCI) orsecondary problems that arise after SCI.
One of the drawbacks of using FES is jerky motions in the muscles and limps. Such movements are not only harmful, but results in... 

Many companies feel the need of automatic person identification for tracking entrance and exit of their employers. This system will help the company in reducing security costs, waste of time and increasing security. In this thesis a novel idea for 3d convolutional neural network text independent speaker verification system will introduced. Since many scenarios visionary data like lip motion, besides speech data, is available, in this thesis both of these data streams are used for developing designed speaker verification system. Multimodalily helps the verification system to be more robust to the noise and attacks. One of the main challenges in designing multimodal neural network speaker... 

Nowadays due to increasing environmental considerations and effort to reducing of the fossil fuels consumption, the necessity of hydroelectric power plants development is emerged. The purpose of this study is to suggest a method of spatial analysis for finding sites with appropriate potential for construction of these power plants, using TOPSIS and GIS. In this research, using the Python programming language, in software environment of Arc GIS version 9.3, local hydrological model was generated using the DEM layer and using of streams ordering methods, the overall situation along the river were processed. In the next step, with using of fuzzy TOPSIS algorithm implementation in software...