Sharif Digital Repository

Various agile software development methodologies, practices, and techniques have been proposed in the last decade; some present novel ideas, while many are simply made up of tasks and techniques borrowed from prominent agile methodologies. Each of these methodologies prescribes a set of practices and techniques which are deemed appropriate for application in a specific context. However, there exists no single method which fits all project situations. This has resulted in the advent of Situational Method Engineering (SME) approaches, which are used for developing software methodologies that are tailored to fit the specific circumstances of the project situation at hand. Since tool support has... 

In recent years, with the growth of software engineering, agile software development methodologies have also grown substantially, replacing plan-driven approaches in many areas. Although prominent agile methodologies are in wide use today, there is no method which is suitable for all situations. It has therefore become essential to apply Situational Method Engineering (SME) approaches to produce agile methodologies that are tailored to fit specific software development situations. Since SME is a complex process, and there is a vast pool of techniques, practices, activities, and processes available for composing agile methodologies, tool support-in the form of Computer Aided Method... 

By expansion of digital multimedia and networking technology, the problem of ownership protection has become increasingly important. Digital watermarking is an efficient way for copyright protection of digital images. Traditional watermarking techniques degrade the quality of host image by embedding a watermark logo. Facing this problem, a new watermarking approach called zero-watermarking has been proposed. In zero-watermarking methods, the watermark does not require to be embedded into the protected image but it uses both the watermark and the protected image to generate a verification map which is registered to a trusted authority for further protection. In this paper we propose a robust... 

Recently, protecting the copyright of digital media has become an imperative issue due to the growing illegal reproduction and modification of digital media. A large number of digital watermarking algorithms have been proposed to protect the integrity and copyright of images. Traditional watermarking schemes protect image copyright by embedding a watermark in the spatial or frequency domain of an image. However, these methods degrade the quality of the original image in some extend. In recent years, a new approach called zero-watermarking algorithms is introduced. In these methods, the watermark does not require to be embedded into the protected image but is used to generate a verification... 

Watermarking is a way that is used to protect the copyright of images. As the existing watermarking methods are not robust enough a new novel scheme is needed. In this paper, we propose a zero-watermark discrete cosine transformation-based copyright protection scheme, in which a normalization procedure is applied in both watermark embedding and extraction to make our scheme more robust to geometric distortions. This method is resistant to malicious signal processing and geometric attacks such as blurring, JPEG compression, noise adding, sharpening, scaling, rotation and cropping. Experimental results on images with different complexity show that our proposed scheme outperforms related... 

We propose an effective blind image steganalysis based on contourlet transform and Zernike moments that improves the detection accuracy of universal image steganalysis methods. The proposed method examines randomness in the test image to distinguish between the stego and non-stego images. The suspicious image is decomposed by contourlet transform, and then the absolute Zernike moments of contourlet subbands coefficients of the image and linear prediction error of each contourlet subband are extracted as features for steganalysis. These features are fed to a nonlinear SVM classifier with an RBF kernel to distinguish between cover and stego images. Experimental results show that the proposed... 

Three-dimensional analysis of combustion chambers in industrial gas turbines suffers from lack of simple and accurate reduced mechanisms for oxidation of hydrocarbon fuels. Here, an integrated procedure is introduced based on a differential evolution optimization technique. The procedure is flexible and modular and allows optimization of many rate parameters of a multistep global mechanism based on many different combustion criteria and inlet or operational conditions. The procedure uses any selected chemical reactor model and any reference combustion mechanism provided. Sample design criteria used here are flame temperature, ignition delay time, and concentration of selected species,... 

It is well known that in a quantum phase transition (QPT), entanglement remains short ranged [Osterloh et al., Nature (London) 416, 608 (2005)NATUAS0028-083610.1038/416608a]. We ask if there is a quantum property entailing the whole system which diverges near this point. Using the recently proposed measures of quantum macroscopicity, we show that near a quantum critical point, it is the effective size of macroscopic superposition between the two symmetry breaking states which grows to the scale of system size, and its derivative with respect to the coupling shows both singular behavior and scaling properties  

Laser excitation pulses that lead to perfect adiabatic state transfer in an ensemble of three-level ladder atoms lead to highly entangled states of many atoms if their highest excited state is subject to Rydberg blockade. Solution of the Schrödinger equation shows that it is increasingly difficult to ensure the adiabatic evolution as the number of atoms increases. A diminishing energy gap, significant variations in collective observables, and increased work fluctuations link the critical slowing down of the adiabatic evolution with a quantum-phase-transition-like behavior of the system. © 2018 American Physical Society