Sharif Digital Repository

Due to daily decrease of fossil energy resources, increase of environmental pollution which is included of toxic and greenhouse gases, and extensive growing rate of demands in transportation industry, especially vehicle industry, developing solutions in using fuel cells are vital for this industry in our country. Fuel cells are green, efficient and also powerful energy generators. According to potential advantages of fuel cells, structure, performance, benefits and also types of fuel cells are introduced as a desired energy resource. Indentifying existing choices of energy generators and ranking them using MCDM (Multi-Criteria Decision Making) technique was the first step to perform a... 

Nanotechnology requires a number of infrastructures for reaching its sustainable development. For each step of its development , various infrastructures should be studied and prepared in advance.In this direction, by introducing and recognizing the priority of Iran Nanotechnology R&D indexes ,the present research is going to propose an effective help. In this case, after studying the related literature and gathering the needed data , 27 indexes were recognized. Then , the indexes were divided in 7 criteria.In order to find the priority of the applied indexes , Fuzzy Multiple Criteria Decision Making (FMCDM) was applied. As the weighting of 7 criteria had been found by FANP , the... 

Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymers (PSU and PES) with nanoparticles TiO2, were prepared for air humidification. The mechanical properties and morphology of these membranes were studied by Tensile Tester and SEM/EDX. The effects of membrane composition and operating factors on humidifier performance were investigated. The results revealed that the membrane composition and its structure have significant effect on humidification. The porous membranes with finger type cavities had higher humidification performance but lower mechanical properties. The Membranes which were prepared from polysulfone polymer, 10 wt % of polymers in casting solution and... 

In the recent years, field effect transistor has been made by using graphane. But there has not been any study about bipolar transistor. Bipolar transistor can’t be constructed using graphene due to the fact that its band gap is zero. So in this thesis, in an attempt to remove this difficulty, the bipolar transistor made using graphane has been investigated and their property has been compared to those of three dimensional silicon transistors.
At the beginning of the thesis, we will have a review of graphane diode and will consider the procedure for evaluating its current which would be the report of what has been done sofar. After that we made graphane transistor using graphane diode... 

Computational Nano Mechanics growth has led researchers towards the development of new multi-scale models. Accordingly, in this dissertation, a step was taken towards introduction, presentation and creation of a new concurrent multi-scale by studying the feasibility of coupling of molecular dynamics methods and temperature related Cauchy-born.To do so, firstly, the above mentioned methods have been studied and then in order to perform molecular dynamics simulations, a program written in C++ language has been used. The accuracy of the written code has been confirmed through studying intuitive phenomenon of gas perfect particle exit from cylinder with an open end. The interpretation of out put... 

Technology node scaling in recent decades ushered in gate delay cut-off and rise of interconnection latency. Hence, interconnects have become a major performance bottleneck of high performance system-on-chips (SoC) and integrated circuits (IC). In addition, interconnectiosns have become more susceptible to noises in particular crosstalk. On the other hand, the advent of multi-core processors with ever increasing number of cores has highlighted the need for fast and reliable interconnections. One of the potential solutions to alleviate the interconnection delay problem is the three dimensional integration using through-silicon vias (TSV). Vertical integration of IC dies using TSVs offers high... 

Solar energy is one of the man's solutions to cope with problems involved in exhaustible fossil resources. In this regard, using photocatalysts is a practical and rational pproach.Nanotechnology facilitates using catalysts and photocatalysts with more productivity.TiO2 semiconductor is one of the most popular material in this field but its efficiency is low by several factors such as being inactive in visible light, recombination and the high cost of using noble metals. In this research, we tried to fix these limitations by creating a p-n junction TiO2 - NiO nanocomposite. The samples are made by three methods: impregnation, ultrasonic assisted modified impregnation with ammonium hydroxide... 

In past two decades, the direction of oil and gas exploration has moved towards deep water drilling. The pressure and temperature in these zones are ideal for gas hydrate formation that can cause serious and sometimes uncontrollable issues during drilling operations. Gas hydrate formation while drilling can cause problems such as occurrence of kick and blowout, plug chock and kill line, and change in rheology of drilling mud. On the other hand, nowadays, nanotechnology has created an evolution in engineering sciences and because of the wide range of this science, drilling industry is affected like other industries. In the meantime, because of high yield, high stability and various methods of... 

If the size of the conventional telecommunication antennas -that are widely used in transmitting broadcasted radio and TV messages- is reduced by a nanometer size these antennas can be used at optical frequencies. Dimensions of these optical nanoantennas -that made of nanoparticles with highly permittivity- can be smaller than half of the wavelength. Based on this capability, optical nanoantennas have some important applications such as optical communication, photovoltaic devices, non-classical light, and optical sensing. After studying on optical nanoantennas and their features, in this project, we present distinctions between optical NAs and MW antennas and then investigate about different... 

Innovative small tech companies are required to often have cooperation with large companies in order to scale-up and commercialize their products. Such cooperation is referred as “Technological Cooperation” since it relies on development and commercialization of technology. In this research, as a multiple-case study in the arena of nanotechnology, five cases of technological cooperation are analyzed and key successful factors are identified. In this endeavor, 15 comprehensive interviews were conducted with both small tech companies and technology applicant companies, including experts of Nanotechnology Innovative Council (INIC) – playing the role of a mediator. Due to lack of a comprehensive... 

The development of Nanotechnology increasingly has elevated the urgency for the expansion of modern numerical and computational methods that have evaluating systems with capability at this scale. In spite of being fully capable of evaluating nanostructures, the existing techniques, such as Molecular Dynamics Methods, lack the ability to simulate large systems of practical size and time scales. Thus, being able to create a large model of realistic simulation, which is confined by the computational expense of the running Molecular Dynamics methods at hand, Coarse-Graining technique has recently become a very effective and beneficial method which refers to the development of simplified models of... 

In these days world, the increasing growth of Nanotechnology has caused to invent and create new numerical and also computational methods which have more abilities and capabilities for evaluating systems in this scale. Although Some techniques, such as Molecular Dynamics Methods are capable of evaluating nanostructures, lack the ability to simulate large systems of practical size and time scales which is the most important index during the simulation. Therefore, in order to be able to produce an acceptable exact simulation of a large model, simulation of which is limited by the computational cost of the current molecular dynamics methods at hand, Coarse-Graining technique has recently become... 

The limitation of energy resources and the increasing energy consumption has led researchers to look more closely at industrial processes such as condensation to improve these processes and prevent energy wastage. Increasing the efficiency of the condensation process will improve the performance of energy systems, save energy and protect the environment. In this research, various surfaces are fabricated, each of which in some way makes it possible to improve the condensation process. To perform the condensation test, the condensation surface, which is placed in the condensation test chamber, is cooled with a heat exchanger. Due to the high temperature of water vapor, many of the surfaces...