Sharif Digital Repository

The human brain is the most sensitive and important human organ and surgery must be done with high precision and without risk. During surgery, brain tissue deform continuously due to gravity, out of the cerebrospinal fluid and the changing pressure of the cerebrospinal fluid and the surgical maneuvers. Because the surgeon has no direct view on brain internal, the ways to solve this problem is to pay attention. This method makes it possible to the surgeon see in the brain and the brain tissue deformation. This thesis method is based on biomechanical modeling. After forming finite element model from the pre-operative MRI, brain surface and volume datasets during surgery as a load, apply to the... 

Crude oil is naturally not applicable to the refining processes to obtain important products. Most of the crude oil refining process produce heavy hydrocarbons that are not used much in the same way. More refineries are looking for a process to remove the heavy components and converts these materials into valuable material. There are different process for upgrading heavy residual oil. One of the main processes in residual upgrading is Delayed Coking. The high flexibility to the different feeds and no need for a catalyst, causing a shift in the approach to the refinery for processing heavy crude oil by Delayed Coking. The aim of this project is calculated the sulfur content and and yield of... 

Embedded real-time systems have limitations on power consumption, mainly due to battery usage and temperature constraints. In addition, a large part of these systems has timing constraints. These constraints should be considered when we use power management techniques. Nowadays, due to the use of fault-tolerance techniques, power consumption and especially peak power consumption are increased so it can miss Thermal Design Power constraint. Recently, due to the conservative design of TDP for chips, it is not considered, and hence, a new power constraint as Thermal Safe Power is defined for thermal and power characteristic of the system. The purpose of this study is to define an optimization... 

In this work, design and construction of copper vapor and Cu Br laser is explained. By special design of copper electrodes the average power from Cu laser system was increased more than 20% in comparison to the same system with expensive electrodes made from molybdenum. However, the basic goal of this work was the construction of CuBr laser. Based on the home made fast trigger unit for Hydrogen thyratron, operation of the manufactured system was possible up to 25 kHz. By using special designed copper electrodes very uniform operation of CuBr plasma diluted in Ne gas was observed. By tuning of the laser parameters such as gas pressure, exciting voltage and pulse repetition rate, from 9 Cm3 of... 

Distributed feedback dye lasers are among the suitable candidates for spectroscopic applications due to their capability of producing widely tunable picosecond pulses in UV-IR region. However, the pulsewidth sensitivity of the laser to pump intensity fluctuations hinders its suitability for precision applications. In this thesis, by utilizing widely used Self Q-Switching model, we showed that if the dye solution is pumped by a narrow (sub-nanosecond) pulse, the laser can operates in the single-pulse output mode with a better stability over a wide range of pump intensity. After that, we used a dynamical model based on the induced polarization and Maxwell equations, where the obtained results...