Sharif Digital Repository

This thesis examines a new electromagnetic mode called line mode. This mode occurs when the boundaries have complementary surface impedances. It is possible to control the mode confinement by changing the surface impedance values. Impedance surfaces with non-complementary impedances guides the quasi-line mode, which is a mode between the line mode and the edge mode. Essential features of the line wave are its singularity over the line, its broad bandwidth, and its robustness to certain defects. Another significant characteristic of a line wave is that unlike surface waves in which it is not possible to change the spin orientation, in a line wave, the spin orientation can be altered by... 

The purpose of this study is to identify and evaluate the risks of new contracts for Iranian oil contract IPC response to these risks During the past three decades Public attention on studies related to the risk of spread with great speed So that the review process as an effective and comprehensive common And covers almost all aspects of life. In theory, any contract associated with the degree of risk. Risks cannot be completely eliminated therefore; scientific approach to the problem of risk is nothing Apart from its management. With the development of the oil and gas industry, identify and manage risk is also of special importance in regulating international oil contracts and has been... 

In this research the effects of cooling slope angle and the temperature of molten steel on globular structure after holding the samples at semisolid state have been investigated. The globular structure of high speed steel in the form of rolled - annealed and as cast condition, has been investigated in the semisolid state. The results showed that the grain sizes of cooling slope samples were lower than the rolled- annealed samples after holding at semisolid temperature. On the other hand, rolled-annealed solid grains had better roundness compared with cooling slope samples. Dissolution of carbides in the austenite phase at grain boundary leads to formation of globular particles in the... 

The telecommunication manhole is a place that the cables of the telephone network are located on it. line Inside these manholes, there are equipment and cables for telephone. The number of these places is many, so protection and maintenance of the manholes have been problematic in case of theft of the cap, equipment inside them and flooding. Also, lack of inspection officers and the high cost of repairing and replacing parts inside them, has made it difficult for telecom companies to handle these problems. The only way to connect the manhole is a telephone line inside them. Also, there is no proper electrical power inside the manhole, so the design and implementation of a system that... 

Efficient radio frequency (RF) power amplifiers (PAs) are critical in portable battery-operated wireless communication systems because they can dominate the power consumption. Linear amplifiers are enough linear but suffer from poor efficiency. On the other hand, switching power amplifier are efficient but are nonlinear and just amplify constant envelope signals. Two conventional methods for increasing transmitter efficiency and linearity are envelope elimination and restoration (EER) and envelope tracking (ET). In both methods, supply modulator controls RF power amplifier supply based on the signal envelope. Efficiency and bandwidth are critical factors in supply modulator. Thus hybrid... 

Various safety systems have been designed and developed in recent decades, but one of the most important issues is the improvement of safety of such systems and that is the goal of this research. In this thesis, while introducing different methods of designing an electronic system, we designed one of these safety systems: the Airbag system in accordance with ISO 26262 by considering standard requirements, prediction of potential hazards of the system, and its safe design at the system level. The designed system is capable of detecting the car crash in a precise and timely maner. The airbag will deploy within 45 milliseconds protecting the health and safety of occupants of the car and in... 

Wireless Power and Data Transfer (WPDT) is a major part of a biomedical implant system. Maximiazing the Power Transfer Efficiency (PTE) and maximizing the data rate are the main challenges in WPDT. In a conventional biomedical implant system, a single inductive link is used to transfer both power and data from outside the body to inside. Data is transmitted by modulating one of the carrier signal properties, i.e., amplitude, frequency or phase. While being simple and robust, this method suffers from the fundamental trade-off between the PTE and data rate. To address this issue, various methods have been proposed including multiple carriers and multiple inductive links, and inductive link... 

The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and...