Sharif Digital Repository

In this thesis we are going to improve an ultrasonic flowmeter accuracy by considering the influence of different parameters like temperature, pressure, etc. Firstl of all different cases of flow condition in which ultrasonic flowmeter may work are specified, then velocity and temperature profile of pipe flow are determined using Fluent software. In thr next step ultrasonic pulses transmitted are simulated by the use of code written in Matlab to find wave travel time in the flow. Evetually an accurate relation of calibration for flowmeter is determined by the use of travel time and all other flow properties to evaluate the accuracy of flowmeter in diffent cases. Relation extracted can be... 

The iron and steel industry has faced several challenges during the recent years. There has always been an aspiration towards higher economic profitability for the system. During the mid 1970s and 1980s the energy crises caused a dramatic rise in energy costs, which led to an increased awareness in energy conservation. In recent years, climate change issues have become more important for the industry. The operating practices for an industrial system are often affected by external restrictions concerning the economical, energy and environmental efficiency of the system. There are a large number of ways to increase the system efficiency, e.g. installation of new process equipment, and practice... 

Study the potential and internal resistance of the electrochemical cells in different states of charge are important for practical and usage. Measurement of these parameters in an electrochemical cell is inseparably bound to the electrochemical resistance, temperature and also geometric states of different parts of the cell. In This project we focus on power and resistance of one kind of batteries called thermally activated batteries. These batteries are active after receiving heat and they are inactive at room temperature. Two of the most important models of these batteries that are discussed in this project are LiSi/ LiCl- KCl / FeS2 battery ( with liquid - molten salt electrolyte ) and... 

The research is performed to study the process of policy making and policy implementation of initiating student education network (Shaad) as as the first official platform of virtual education in Iran. We want to compare this process with “Kingdon’s multiple stream model”; because shaad initiated shortly after the closure of school’s caused by the outbreak of Covid-19 virus, while in recent years there have been several failed attempts to launch formal e-learning plans. Data were gathered trough semi-structured interviews of experts with shaad founders (11 people), reviewing some of the related documents and news, and unstructured observation by researcher. The findings were coded using... 

A mechanical system inherently affected by the conditions, factors and parameters of uncertainty. Without including the uncertainty effects in the optimal design procedure, the mechanical system will not be reliable. To include uncertainty effects in an optimum design, there are two different approaches; the robust design optimization and the reliability based design optimization. In robust design optimization process, the main aim is to enhance the system performance by minimizing the variations. In reliability based design optimization process, the target is that the optimal design variables to be in appropriate reliably levels. In this paper, a new model for the reliability based robust... 

Today, smartphones became a universal technology, and mobile networks speed and bandwidth have increased. Additionally, some of the messengers support voice call services that are easy to use and economical. Many of the VoIP servers provide encrypted VoIP service. On the other side, ISPs need to recognize the VoIP flows to enforce their policies. In some case, ISPs should block illegal VoIP calls or fix a specific charge for them. Also, for providing a better quality of service, it’s necessary to decrease the delay of VoIP packets. Most related works have concentrated on the methods of detecting VoIP traffic that just worked on a specific application. Some other works detect VoIP by using IP... 

Spent Caustic is the waste resulting from scrubbing of hydrocarbon streams with caustic solution. A thorough research on wastewater treatment to be performed at Tehran Oil Refinery in order to eliminate acid gases such as CO2 and H2S from LPG obtained from scrubbing given the fact that these gases are not eco-friendly, and the current systems of wastewater treatment are inefficient. Therefore, after investigating different methods used in Spent Caustic treatment, WAO method has been chosen to treat the wastewater at Tehran Oil Refinery. In this method, wastewater is oxidized with air at high temperature and pressure to reduce its COD. However, its high cost and operational difficulty of... 

In recent years, due to the structural need of most medical data for graphic models such as the graphic model of patients and the loss of data correlation in previous methods, graphic methods have been designed and developed. On the other hand, with the growing presence of magnetic resonance imaging devices in various medical centers, a large amount of functional magnetic resonance images of healthy and sick people have become available to researchers. In this study, our goal is to use a new method in the field of graphic modeling so that we can extract functional connectivity graphs from functional magnetic resonance images and measure the performance of these graphs in different groups of...