Sharif Digital Repository

The chemical vapor deposition (CVD) of graphene from methane on a copper substrate is the most promising method for production of large-area graphene films. There have been long-standing challenges in this field such as controlling the graphene coverage, film quality, the number of layers, and the nucleation density of graphene domain. These challenges can be overcome by developing a fundamental understanding of the graphene growth process. The main aim of this study is to control nucleation density of graphene domains. Chemical vapor deposition (CVD) graphene is polycrystalline, and grain boundaries in graphene film have been identified to degrade the properties of graphene as a membrane... 

Thin film graphene oxide(GO) membranes have been promising potential for gas purification due to thin lamellar microstructure, stable a few atom thick layers and very short intersheet distances. In this research, the nanoporous graphene oxide membranes have been prepared by vacuum and pressurized ultrafiltration on the modified polyacrylonitryle(mPAN) sublayer for helium separation from Nitrogen and carbon dioxide gas mixture. The separation performance of synthesized GO membrane was controlled by varying parameters such as concentration of stabilized aqueous GO solution, pores size range of support and its surface properties, centrifuge time, applied pressure after synthesis, humidity,... 

Wax deposition crude oils, with high pour point causes, many problems arise in production, transfer and storage. In this project, wax appearance temperature of three samples of crude oil caculated, using techniques viscometer. Maximum absolute error on oil.no2 was with a value of 0.559% and the results had in good agreement with experimental data. By using the rheometer MCR301, for three crude oil samples, steady shear tests and sweep time tests was done. Flow diagrams were obtained. According to wax appearance temperature (WAT) of each samples, diagrams shear stress versus shear rate are nonlinear at low temperatures than WAT. Crude oil shows non-newtonian behavior. Arrhenious model,... 

In today’s world the growth in population make food production and also the packaging industry increase. Finding new ways to enhance the efficiency of packaging is become so important beyond researchers. As the randomized co-polypropylene is the most suitable materials for this industry many attempts have been made to control its melting behavior with the aim of expanding their application in the packaging industry. The study in this field indicate the dependence of the melting behavior on the structural characteristics of the material such as molecular mass, chain structure, type of crystalline structure, and the amount of dispersion of the crystals thickness. Due to the lack of proper... 

The number of connected devices through the internet of things is increasing rapidly, which leads to adopting different communication technologies to provide connectivity of this large number of devices. The used communication technologies can be classified into the local area network, low-power wide-area network (LPWAN), and cellular network technologies. The receiver power has a critical role in the total power consumption of utilized transceiver chips in these technologies. Radiofrequency (RF) front-ends are often significant power-consuming parts of integrated receivers. Therefore, system-level design in which the overall specifications are distributed among RF front-end building blocks... 

Considering the drastical increasing of greenhouse gases in the atmosphere, especially carbon dioxide, reduction of these gases seems necessary to combat global warming. Fossil fuel power plants are one of the main sources of CO2 emission. In this thesis, CO2 capture from a natural gas fired combined cycle power plant using different oxygen percent in air feed is studied. Aspen Plus was used to evaluate the effect of this capture technology on the plant efficiency and energetic parameters of the system. Aspen Hysys is used to simulate Amine absorption tower and Air Separation cryogenic tower. Since the oxygen production plant, CO2 capture and transport are cost and energy intensive, the cost... 

Detetrmination of particulate matter (PM), as one of the most important pollutants in big cities, requires extensive system of monitoring stations. Remotely sensed atmospheric data due to their large spatial coverage and frequent observations are emerging as an important addition to conventional ground based atmospheric monitoring. In this regards this study presents an approach to analyze the relationship between PM10 (particles with aerodynamic diameter less than 10 μm) and the satellite product of aresol optical depth (AOD), which is the measurement of the extinction of light due to interferences with particulate matter. In the current study AOD is observed by Moderate Resolution Imaging... 

Intelligent control or management of well or reservoir is a method which is used in order to optimize the production for increasing recovery factor so that the minimum damage or reduction of pressure occurs during production lifetime. Azar oilfield has 17 wells and the production from this field isn't started. Thereupon designing a suitable well completion model and a control algorithm to optimize the production for the first two years of production is necessary and indispensable. For this purpose, by collecting basic information and their analysis (for example pressure, temperature, production rate, the type and amount of produced fluids), designing of downhole installations and modeling... 

A prey-predator fishery model with stage structure for prey is discusing in this thises. The adult preyand predator populations are harvested in the proposed system. The dynamic behavior of the model system is discussed. It is observed that singularity induced bifurcation phenomena is appeared when variation of the economic interest of harvesting is taken into account. We have incorporated state feedback controller to stabilize the model system in the case of positive economic interest. Fishing effort used to harvest the adult prey and predator population is used as a control to develop a dynamic framework to investigate the optimal utilization of the resource. Simulation results show that the... 

In this thesis we have investigated and improved the signal processing techniques which are used for monitoring the heart abnormalities in terms of ECG (ElectroCardioGram) signals in order to detect heart attacks before they occur. De-noising ECG signals are one of the most important research topics in computer and electrical engineering fields. There are many different algorithms for de-noising signals in various domains. It usually is needed to propose a suitable algorithm for each specific system. In some cases instead of developing a new algorithm, we could modify the available ones for de-noising in our system. ECG signals are output from an electrocardiograph which measures electrical... 

Water base drilling fluids are the most common drilling fluids in oil and gas operations and biopolymers are the requisite additives used in such kind of fluids frequently. Unfortunately, at harsh conditions of HPHT the polymers undergo thermal degradation which cause serious loss in fluid rheological and filtration properties. Accordingly, this will induce operational pitfalls and tremendous cost. The power of economy along with environmental regulations force us to search for reasonable chemically benign additives to fulfill this need. Nanoparticles are the most promising additives proposed in this study to address this challenge. Regarding their unique exclusive properties, they are able... 

The increasing demand for energy forced to production of oil as one of the main sources of energy. Along with the increase in oil production, the proportion of water produced with oil is increasing relative to the oil produced. On the other hand, environmental restrictions for the discharge of industrial effluents into the environment are becoming more and more stringent every day. Before discharging the effluent into the environment, petroleum must be removed. The complexity of these issues demonstrates the need to develop new technologies and improve the efficiency of existing technologies. Gas flotation are among the technologies adopted in the field that have been used throughout the...