Sharif Digital Repository

Ant algorithms are optimization algorithms inspired by natural behavior of real ants, which can find the shortest path between nest and food. These algorithms are used to solve numerous complex optimization and combinatorial problems. In recent years, ant algorithms have been used in image processing, specially in edge detection. Edge detection being important and having applications in image processing, several edge detection algorithms have been presented. Our goal is to study edge detection processes based on ant algorithms. Four algorithms recently proposed in the literature are implemented, and the results presented by their authors are verified. Furthermore, implemented algorithms are... 

Image processing is very important in several applications. Here we use a rectangular grid for image processing. Other approaches exist in the literature. One new approach is to change the grid from rectangular to hexagonal, due to its various advantages over the latter. Main advantage of the hexagonal structure in image processing is its resemblance with the arrangement of photoreceptors in the human eyes. The change in arrangement amounts to requiring less pixels. There is no inconsistency in pixel connectivity and thus angular resolution is higher in this arrangement. Our goal here is to study lossless compression algorithms for images with hexagonal pixels. First, we consider the... 

Skin cancer is a common type of cancer in the world. Melanoma is considered as the deadliest form of human skin cancer that causes approximately 75% of deaths associated with this cancer. However, melanoma is curable if diagnosed in an early stage. Due to high visual similarities and diverse characteristics of lesions, it is a challenging task to differentiate between different types of skin lesions. Therefore, it is worthwhile to develop a reliable automatic system increasing the accuracy and efficiency of pathologists. Here, we propose sparse representation and dictionary learning based methods for skin lesion segmentation and classification. First, we review the steps of a computer aided... 

The climate crisis and the role of the energy sector in greenhouse gas emissions highlight the urgent need for a transition to a low-carbon energy supply system. In this study, the OSeMOSYS model was used to optimize emission reduction pathways by implementing various scenarios, including BAU, NZC, SSP1, SSP2, and SSP5. First, the technical parameters of the model, such as investment costs and capacity factors, were estimated using econometric methods to account for technological development. Sensitivity analysis was then conducted on investment and import constraints. The results indicate that the BAU scenario, due to its high reliance on fossil fuels, leads to the highest CO₂ emissions,... 

By using an encoding scheme based on Algebraic Integers (AIs), we study in this thesis how to map the real numbers needed in the computation of the FFT to integer numbers, in order to prevent error production and propagation throughout the intermediate stages of the FFT computation. To reconstruct encoded data, a decoding stage is to be used at the end of the FFT computation. AI-encoding poses two challenges; how to determine suitable AI bases and an unwanted growth in the number of data passes. This research work, firstly, determines an appropriate FFT architecture, and then, proposes a dedicated architecture based on AI-encoding. The basic and also the proposed dedicated architecture are... 

Design and production of a drug is a very time and money consuming process. It takes more than a decade and about 2.5 million dollars on various stages to design a drug. Attempts to reduce this cost and time to market will make drugs available to customers at a more reasonable time. Some stages such as animal testing phase and clinical trials, can not be replaced and must take place in practice. Fortunately, some laboratory steps are interchangeable with software algorithms. These algorithms can significantly reduce the cost and time to market of the drug if they are accurate enough. On the other hand, the remarkable results of machine learning, in particular, Deep Neural Networks, in areas... 

Nowadays, power systems and substations are the most important components of the vital infrastructure of a country, which handle the production, transmission and distribution of the electrical energy. Automation systems increase the efficiency of the power industry while making remote control possible, but the use of computer-based control systems is a potential field for cyberattacks which may cause equipment destruction and electricity network destabilization. One of the main requirements for the utilization of digital substations is the synchronization between different equipment used in it. Several algorithms and protocols have been proposed so far for time synchronization in distributed... 

Micro-Robotics is implemented by researchers inclusively in last decades in different fields such as, biolotechnology, space, army and medical engineering. However, micropositioning is the main challenge in such projects, since determination and control of micro-robot’s position for drug delivery, artificial insemination and other medical applications are too significant. In this thesis, a method for controlling a microswimmer’s position in two dimention by an external magnetic field has been proposed. Modelling of magnetic field and magnetic gradient are some important challenges due to the fact that in control loop, a fast and optimal model for estimation of magnetic filed and gradient is... 

The use of aluminum and its alloys in different industries is increasing. To increase the deformability of Aluminum alloys, it is usually deformed at high temperatures. In Such working conditions, the chemical composition, temperature of deformation, strain rate and high temperature activating phenomena will affect the microstructure and final properties of the material. In this thesis the hot and cold deformation behavior of a Al-11.77%Si-0.2%Mg are evaluated. In the cold deformation, the alloy was first annealed and then ECAEed. The mechanical properties and the related microstructure were evaluated via the microhardness test. The results indicated that the alloy could not be deformed... 

Capsule endoscopy is a minimally invasive diagnostic technology for gastrointestinal diseases providing images from the human’s digestion system. Developing a robust and real-time localization algorithm to determine the orientation and position of the endoscopic capsule is a crucial step toward medical diagnostics. In this thesis, we propose a novel model-aided real-time localization approach to estimate the position and orientation of a magnetic endoscopic capsule swimming inside the stomach. In the proposed method, the governing equations of the motion of an ellipsoidal capsule inside the fluid, considering different hydrodynamics interactions, are derived. Then, based on the dynamic... 

The IEC61850 Standard was introduced for IED, Intelligent Electronic Device, in a power substation so that different devices from different manufacturers could work together. Each of these devices must be configured to start communication. Chapter 6 of the IEC61850 Standard discusses the configuration language of these devices, SCL, Substation Configuration Language, as well as how to write it in detail.A failure or denial-of-service attack can occur in a power substation if a tampering or embedding a breach in devices’ configuration occurs. To discover such attack, one can model the behavior of all the components in the SCL language using a language describing the behavior, and then compare...