Sharif Digital Repository

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 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... 

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... 

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... 

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... 

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... 

The notable share of housing sector in GDP (approximately five percent) shows this sector’s relation with macroeconomic activities. On the other hand, House as an asset leads housing sector to be affected by monetary and fiscal variables. A dynamic panel data was used in this study to evaluate the relations between housing sector and some macroeconomic variables in metropolises of Iran. As results show, in long term growth of liquidity, GDP per capita and sharp ratio have positive effects, and land per capita has negative effect on housing price in metropolises of Iran. Price increases have not been equal in different cities. Inequality of land price between metropolises and between... 

In this research, an Index of Iran informal economy in response to the government interventions in credit, labor and product markets is stimated by EMIMIC model. To do this, first these interventions are measured using principal components analysis. In the model, the variables GDP and employment are used as indicators and taxation rates, government distortions in credit, labor and product markets, government expenditure, per capita income, unemployment and inflation as causes of the informal economy. We conclude these government interventions have affected Iran informal economy and their influence is more than indirect interventions influence such as taxation. The estimated index of Iran... 

With altering natural state and increasing impervious surfaces, traditional urbanization leads to deteriorating the environment and water catchments. During the years most efforts in order to control the urban runoff outflow, have been focused on quantity; and awareness about improving water quality has been raised just in the last few years and, which emphasizes on pollution source control. Standard water quality sampling methods are time consuming, expensive and because of sampling in broad geographic areas, difficult; however modeling is a more efficient way in assessing water quality and as worries about non-point source pollution grows, different kinds of models have been used to... 

The role of government in economy has been a controversial subject in economics. Lately, there has been some fundamental change in evaluating this subject. One could mention two of these as 1) realizing the importance of micro-founded macro model for evaluating policy, and 2) taking into consideration the rent-seeking behavior of politicians. In this research, a general equilibrium in a micro-founded macro model will be discussed and then in political economics framework, the effect of government on this equilibrium will be investigated. Only the redistribution role of government has been considered. First, the model in which a benevolent government is seeking optimal policy is Discussed.... 

Gini coefficient is the most prevalent index for the measurement of inequality and is usually extracted by means of nominal variables based on income or expenditures of households. In this study we have extracted more accurate Gini coefficients. By using the raw data of Households Budget Survey (HBS) and STATA software, a special CPI for each household of the sample is extracted. Subsequently nominal expenditures are deflated by these special CPIs, and at last, Gini coefficients are extracted from real expenditures. Our findings indicate that in recent years, extracted Gini coefficients are remarkably higher than prevailing ones.
 

This paper investigates the behavior of the Y-shaped bracing system. Because of the special type of eccentricity in this system, the behavior of the frame is strongly dependent on the geometrical changes of the braces. So that even in the elastic region, it shows the geometrically nonlinear behavior. The amount of eccentricity is very effective on the nonlinear behavior of the frame. Also the ratio of cross sections of the bracing members has a very important impact on the expected performance of the frame. The results show that this system tolerates large displacements, and can act like a base isolation system. Firstly, using a two-dimensional accurate modeling related to the geometrical... 

The Overstrength, Ductility and the Response Modification Factor (R) for 70 steel X-braced , Inverted-V-Braced and Offcenter Bracing System frames were evaluated by performing pushover analysis of model structure with various stories (3,6,9,12&15 story) and span length (4,6&8 meter). Some result were compared with those from nonlinear dynamic analysis. According to the analysis result the R factors obtained from nonlinear dynamic analysis are 15% more than obtained from pushover analysis and R factors computed from pushover analysis were generally smaller than the values given in the design codes. R factors in Irregular structure in height are about 90% of R values in regular structure in... 

Maghemite (γ-Fe2O3) nanoparticles were produced after high temperature oxidation of gelatin-Fe3O4 nanocomposite, obtained from a common coprecipitation process of Fe2+ and Fe3+ ions in an alkaline medium in the presence of a gelatin protein as an effective mediator. Size, shape, surface morphology and magnetic properties of the prepared γ-Fe2O3 nanoparticles were characterized using XRD, FTIR, TEM, SEM and VSM data. The results revealed that primary, gelatin-Fe3O4 nanocomposite had been formed and next, the gelatin decomposition in furnace produced a spinel structure of γ-Fe2O3. The effects of furnace temperature and time of heating together with the amount of gelatin on the produced... 

The Response modification factor R represents the behavior of the structure such as ductility, overstrength and the inherent redundancy. This factor shall be defined according to the type of lateral force resisting system. However, there are some complexities and/or uncertainties in codes related to the R factor according to the height, form of irregularities and structural systems. Therefore, from the scientific point of view as well as reliability, it is very clear that the R factor cannot be similar for all kinds of structures, categorized as a specific group. In this investigation, assuming a low-rise, vertically irregular structure with a heliport which has a dual structural system... 

Maintaining the quality of water is of paramount importance for lakes with tourist attraction capacity. Inaccurate prediction of the quality state of lake in design phase may lead to some trouble in future. Kan River known as the main source of water feeding for the urban lake located in the north of Chitgar park passes through various villages and restaurants discharging nutrients via runoff and wastewater in the aforementioned river. Previous investigations reveal that phosphorous plays a central role in the water quality of this river and the associated downstream lake. In this research, Kan watershed,located in in the north-west of Tehran, was simulated. Considering the "Total Maximum...