Sharif Digital Repository

Todays the use of microwave integrated circuits for military and commercial applications has gained much attention, especially with the advent of monolithic microwave integrated circuits, which provide the possibility of fabrication of amplifiers in large number, sufficient accuracy an affordable price.GaAs pHEMT process, because of good characteristics for noise and power in high frequencies, is a good choice for microwave and millimeter wave integrated circuits. A low noise amplifier is a key block in the receiver and, its noise figure and gain directly affects the sensitivity and dynamic range of the receiver. Hence, a low noise amplifier with low NF, high gain, good return loss, low... 

In this project, production of nano and micro particles with laser ablation of zinc, silver and copper sheet metals in the liquid medium has been experimentally studied. For this aim, homemade Nd:YAG pulsed laser at 1064nm wavelength, 60μs pulses with excellent stability with energies up to 700mj is used. By changing the pulse intensity on the target surface, the parameters such as size, shape and optical properties of nano and micro particles are studied by UV-visible spectroscopy, DLS, and SEM techniques. In this work, by microsecond pulses of Nd:YAG and using measuring devices such as Coherent power /energy meter, the appropriate optical table, the related experiments are implemented.... 

Optimization and uncertainty are two main issues in the structure design. In engineering problems and specially the structure, loads are among those issues witch we cannot be commented definitively. The uncertainty also shows itself in material properties and structural shapes. Design optimization is inevitable in order to use resources effectively. In the past, structural design was based on experience and engineering judgment, which was conservative and sometimes structure weight was very high. But today, thanks to computers, high-volume calculations would not be out of reach. With considering uncertainty, we can have prosper sight toward constraints by maintaining proper distance from... 

One of the novel methods of stabilization of nuclear waste is the use of vitrification technology. In order to stabilize high level wastes (HLLW) in glass, it is required that the elements are in their oxide form. Therefore, it is necessary to evaporate the waste and turn it into a solid form so that the elements can be converted into oxide form in the calcination furnace. Hence, one of the challenges of stabilization is the optimization of evaporation and calcination conditions. In this research, the parameters affecting evaporation were first investigated. Using laboratory measurements of application: temperature (110 to 180 °C), presence of nitric acid (0.5 to 4 mol/L), ratio of zirconium... 

This study used the emulsion liquid membrane method to investigate the extraction and separation of thorium from nitrate solution. According to the results obtained from the studies, Cyanex 272 was a suitable option for selectively extracting thorium. For simultaneous extraction and stripping of thorium from dilute aqueous solutions, an emulsion liquid membrane system consisting of Cyanex 272 as an extractant, Span 80 as a surfactant and sulfuric acid solution as a receiving phase (internal phase) was used. Emulsion liquid membrane method has high mass transfer flux due to high surface to volume ratio, which causes high extraction efficiency and fast transfer of thorium ions from its low... 

With deployment of distributed generation such as photovoltaic (PV) and active prosumers along with demand response (DR) ability, new fields are being created for energy markets and they are moving towards a consumer-centric way. Peer-to-Peer (P2P) network is one of the top research focuses which many studies have been conducted recently. The P2P network is based on multi bilateral agreements between Prosumers that help each other to manage and balance the supply and demand of energy between each other. In this thesis, two important structures of P2P network, which are called community-based and fully-decentrilized, respectively based on MILP (mixed integer linear programing) and ADMM... 

One of the most common spinal surgeries involves spinal fusion or vertebral fixation, which is used to treat various conditions such as intervertebral disc disease, scoliosis (lateral deviation of the spinal column), fractures, infections, or the presence of tumors in the spinal column. In this surgical procedure, the use of pedicle screws and titanium rods prevents motion and friction between two vertebrae. Screws may enter the vertebrae in the wrong position and angle, causing bone weakening, rupture of nerve roots or blood vessels, weakness or lack of sensation in some parts of the body, spinal cord injury, and in severe cases, paralysis of the patient. For this reason, fusion surgery is...