Implementation and Comparison of Some Steganography Method for Digital Images

, M.Sc. Thesis Sharif University of Technology Chaboki, Behrang (Author) ; Mahdavi Amiri, Nezameddin (Supervisor)

Abstract

In the modern world, steganography is an image processing technique, revealing to be a suitable process for information hiding. In most cases, steganography has shown to be more effective than cryptography techniques. Recently, there have been attempts to improve the stego-image quality and hiding capacity by introducing new methods. Here, we inspect the advantages and disadvantages of some new steganography methods for digital images. The implemented methods are color and grayscale image steganography with OPVSP algorithm, BRL and GRL methods, and the simple LSB method with OPAP algorithm. Here, we compare the implementation results of these methods using MATLAB 7.4.0, with other common...

Theoretical and Experimental Investigation of Flow behavior of Nanofield Viscoelastic Fluids in Contraction Flow

, M.Sc. Thesis Sharif University of Technology Behrang, Arash (Author) ; Ramazani Saatatabadi, Ahmad (Supervisor)

Abstract

In this work, the viscoelastic fluids flow and their short fiber suspensions has been modeled in contraction geometry using conformation models, these models predict behavior of polymeric chains in contraction geometry. Prediction of viscoelastic fluids flow through a contraction is very important, especially in polymer processing where a polymer melt in barrel of an extruder is going to pass through a narrow die. We expect to see an eddy in each corner of barrel. The result has shown that increasing of De number enhances the eddy magnitude; also with making acute angle, we see decreasing of eddy magnitude. Normal stresses and velocity were investigated in contraction and their results had...

Extension of Spatial Competition Model with Raffle

, M.Sc. Thesis Sharif University of Technology Tahvilian, Mehrdad (Author) ; Kamali, Behrang (Supervisor) ; Vesal, Mohammad (Co-Advisor)

Abstract

This research is about raffles held by firms. Nowadays raffles are used by some firms as a mean to attract more customers and obtain more profit to the extent that they compete on their prize instead of their price. In order to investigate this phenomenon, we introduce a model based on spatial competition. This model explains the reason firms have incentive to offer raffles when consumer is risk neutral. According to this model we conclude competing on prize reduces consumers’ surplus considerably. Because of this, the intervention of policy maker can prevent the reduction in consumers’ surplus

Municipal wastewater treatment and fouling in microalgal-activated sludge membrane bioreactor: Cultivation in raw and treated wastewater

, Article Journal of Water Process Engineering ; Volume 49 , 2022 ; 22147144 (ISSN) Najafi Chaleshtori, S ; Shamskilani, M ; Babaei, A ; Behrang, M ; Sharif University of Technology

Elsevier Ltd 2022

Abstract

Since the advent of conventional activated sludge biological treatment plants, their low efficiency in nitrogen and phosphorus removal has become a significant concern. Therefore, in this study, the performance of microalgal-activated sludge membrane bioreactor (MAS-MBR) as a self-biological treatment or as a post-treatment for conventional biological treatments was investigated. A continuous MAS-MBR with two ratios of algae/sludge (only microalgae and 5:1) was used to treat raw and treated wastewater. The optimum case was achieved with the cultivation of mixed algae/sludge in raw wastewater (R2 case). In this case, the ammonium and phosphorus removal efficiencies were 94.36 ± 3.5 and 88.37...

Modeling the Flow and Infiltration of Surface Runoff in Swales

, M.Sc. Thesis Sharif University of Technology Behrang, Koorosh (Author) ; Agha Mohammad Hossein Tajrishi, Massoud (Supervisor)

Abstract

Urbanization and increase in impervious areas owing to building construction, pavements of streets, parking lots and sidewalks, amount of surface runoff in cities has been rose. One of the environmental problems of Tehran during the rainfall is the high polluted runoff flowing in the city and eventually transfers pollution to aquifers. So in order to decline the consequences of this polluted surface runoff, it is crucial to understand how the runoff and pollution form. One way of decreasing pollution in runoff is hiring swales attenuation potential. In this study, problems associated with runoff, particularly in relation to the formation, transformation and removal of pollutants from runoff...

Flow of a PTT fluid through planar contractions - Vortex inhibition using rounded corners

, Article ASME 2010 International Mechanical Engineering Congress and Exposition, IMECE 2010, Vancouver, BC, 12 November 2010 through 18 November 2010 ; Volume 7, Issue PARTS A AND B , November , 2010 , Pages 601-607 ; 9780791844441 (ISBN) Khodadadi Yazdi, M ; Ramazani S. A, A ; Hosseini Amoli, H ; Behrang, A ; Kamyabi, A ; Sharif University of Technology

2010

Abstract

Contraction flow is one of important geometries in fluid flow both in Newtonian and non-Newtonian fluids. In this study, flow of a viscoelastic fluid through a planar 4:1 contraction with rounded corners was investigated. Six different rounding ratios (RR =0, 0.125, 0.25, 0.375, 0.438, 0.475, 0.488) was examined using the linear PTT constitutive equation at creeping flow and isothermal condition. Then the resulting PDE set including continuity, momentum, and PTT constitutive equations were implemented to the OpenFOAM software. The results clearly show vortex deterioration with increasing rounding diameter, so that when rounding corner exceeds a critical value, the vortex disappears...

Designing an Admission Mechanism for Business Incubators

, M.Sc. Thesis Sharif University of Technology Sheikh Zeinoddin, Mehdi (Author) ; Fatemi Ardestani, Farshad (Supervisor) ; Kamali Shahdadi, Behrang (Supervisor)

Abstract

Business incubators admit young startups and help them grow by providing them with a number of services. The startups are put through an admission process, and the incubator is not fully aware of the quality of the startups she is admitting. On the other hand, once inside the incubator, a startup may choose not to exert a high level of effort, as the incubator cannot fully monitor its behaviour. In other words the incubator faces a problem of adverse selection plus moral hazard.Adverse selection and moral hazard between investor and investee (which is not dissimilar to the relationship between incubator and startup) has a vast literature. However, one important difference is that in the...

Integration of the intelligent optimisation algorithms with the artificial neural networks to predict the performance of a counter flow wet cooling tower with rotational packing

, Article International Journal of Ambient Energy ; 2021 ; 01430750 (ISSN) Assari, N ; Assareh, E ; Alirahmi, M ; Hosseini, H ; Nedaei, M ; Rahimof, Y ; Fathi, A ; Behrang, M ; Jafarinejad, T ; Sharif University of Technology

Taylor and Francis Ltd 2021

Abstract

The present study investigated a counter-flow cooling tower performance by integrating the Artificial Neural Networks and Intelligent Optimisation Algorithms (ANN-IOAs). For this purpose, two scenarios were evaluated. In the first scenario, inlet air wet-bulb temperature (T aw), inlet air dry bulb temperature (T ad), water to the air mass flow rate ratio (mw /ma), and rotor speed (υ) were the input parameters for the ANNs, while the output temperature (T wo) was the ANNs output. In the second scenario, the same input parameters applied for the first scenario were used as input variables and the tower efficiency (ε) was considered as an output parameter. The well-known IOAs methods, namely,...

Integration of the intelligent optimisation algorithms with the artificial neural networks to predict the performance of a counter flow wet cooling tower with rotational packing

, Article International Journal of Ambient Energy ; Volume 43, Issue 1 , 2022 , Pages 5780-5787 ; 01430750 (ISSN) Assari, N ; Assareh, E ; Alirahmi, S. M ; Hosseini, S. H ; Nedaei, M ; Rahimof, Y ; Fathi, A ; Behrang, M ; Jafarinejad, T ; Sharif University of Technology

Taylor and Francis Ltd 2022

Abstract

The present study investigated a counter-flow cooling tower performance by integrating the Artificial Neural Networks and Intelligent Optimisation Algorithms (ANN-IOAs). For this purpose, two scenarios were evaluated. In the first scenario, inlet air wet-bulb temperature (T aw), inlet air dry bulb temperature (T ad), water to the air mass flow rate ratio (mw /ma), and rotor speed (υ) were the input parameters for the ANNs, while the output temperature (T wo) was the ANNs output. In the second scenario, the same input parameters applied for the first scenario were used as input variables and the tower efficiency (ε) was considered as an output parameter. The well-known IOAs methods, namely,...