Sharif Digital Repository

Magnetron is one of the microwave-generating devices that operates based on the microwave-electron flow interaction in the active region of the tube, which is affected by the resonant cavities and It is used in a wide range of power (from kW range at home microwave ovens to several GW in relativistic high power magnetrons and the frequencies from the order of few too MHz to tens of GHz). Although nowday's low-power generators based on transistors have replaced microwave generating tubes and even MW radio transmitters are made based on the combination of semiconductor microwave generators, but in the production of RF pulses at higher frequencies and powers, the electron tubes are the main... 

Nowadays embedded system play an important role in human life. The majority of these systems work in harsh environments which intensifies the importance of fault tolerance in embedded systems. This capability is usually achieved by adding redundancy to the system. But common embedded systems are weaker than desktop and server systems and probably have a limited source of power which makes the redundancies expensive. Hardware fault tolerant techniques impose significant cost to system and increase the development time which makes software-only solutions more attractive. An important general purpose software-only technique in protecting the application data is EDDI. This technique is based on... 

Real-time embedded systems play an important role in many areas of human life and energy consumption is an important constraint in their design. In these systems, SRAM-based on-chip scratchpad memories are used for holding code or data which suffer from high leakage power and low capacity per transistor. This has persuaded researchers to find alternative solutions and in recent years non-volatile memories have attracted a lot of attention. Compared to conventional memories like SRAM, non-volatile memories consume less leakage power and provide more capacity given the same number of transistors. In this dissertation, we propose new solutions for reducing the energy consumption of real-time... 

Dissipative particle dynamics (DPD) is an emerging mesoscopic computational method in which the interparticle forces arise because of coarse-graining at the molecular level. In the asymptotic limit of large length scales, the governing equations of continuum are reproduced, as demonstrated in this work. This method of simulation has the capability of simulating larger order of time and space in compare with dynamic molecular method. One of the important applications of DPD is simulating the dilute polymer solution. In this project, we developed a general code to simulate dilute polymer behavior which consists of polymeric forces and different types of usual DPD boundary conditions. This code... 

The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have...