Sharif Digital Repository

One of the main requirements in today’s computer networks such as the Internet is protecting the privacy of users. Hence, anonymity is a useful tool for privacy and provides user’s anonymity. So far, several protocols have been designed to provide anonymity but most of the times, attackers found a way to take advantage of weaknesses in the design and implementation of these protocols. There is a class of attacks,where attacker tries to relate clients of anonymity system to each other, regardless of the communication protocols they use, just by observing networks traffic.The MIX technique forms the basis of many popular ervices that offer anonymity of communication in open and shared networks... 

With a fast progress in nanotechnology devices and components, e.g., MEMS/NEMS, heat transfer study in micro/nanoscales has become so critical for the systematic design and precise control of such miniaturized devices towards the integration and automation of Lab-on-a-chip devices. Demands in high heat transfer rates have returned the concerns to impinging jet cooling systems. However, studying impinging jets in the micro/nano scales is requires the molecular dynamics knowledge to analyze the true micro/nanoscale flow behavior accurately. According to the importance of this subject, we use direct simulation Monte Carlo (DSMC) method to simulate nano impinging jet gas flows. The thesis is... 

In recent years, cancer is the second leading cause of human death. Cancer treatment is based on surgery, chemotherapy and radiation therapy. Choice of treatment method depends on the degree of progression and type of cancer. However, the goal is destruction of cancer cells and minimal harmful side effects on healthy cells. In this thesis two types of polysaccharide-anticancer drug conjugate were prepared and evaluated for radiation therapy and chemotherapy; chitosan- and DTPA modified chitosan – Gallium 66 conjugates for radiation therapy and nano diacid starch –cisplatin conjugate for chemotherapy. Chitosan –gallium 66 conjugate was prepared in radiochemical purity higher than 99% at... 

Generally, virtual loads is used to test all AC power and energy meters and are usually passive. To prevent possible damage of this heat and to control the temperature, cooling blowers are used which increases the volume and weight. So, recycling the power delivered from the grid causes a small amount of power to be converted to heat in proportion to the load efficiency. The purpose of this study is design, predictive controller model for programmable electronic regenerative AC load. The structure used is a back-to-back converter consisting of an AC-DC converter and a DC-AC converter, which according to existence of capacitance between these two structures, two converters can be controlled... 

In the present work, we have designed a novel CdS/CdTe solar cell based on CdS nanowires, as a window layer, and CdTe nanoparticles, as a absorber layer. CdS nanowires and CdTe nanoparticles were synthesized by solvothermal method. The samples were characterized by X-ray diffraction diffractometer (XRD), field emission scanning electron microscope (FE-SEM), Atomic Force Microscope (AFM) and Ultraviolet–Visible (UV–vis) spectroscopy spectrometer. Photocurrent measurements were carried out using a 150 W xenon lamp with an air-mass (AM) 1.5 filter. The performance of the solar cell based on the CdS nanowire (NW-CdS) film with 225 nm thickness and CdTe nanoparticle (NP-CdTe) film with 6 μm...