Sharif Digital Repository

For many reasons the Montecarlo method is chosen for investigation of problems like shielding. Nowadays, superiority of utilizing the codes based upon Montecarlo methods such as using cross sections with continuous energy or using exact models of complex geometries, is obvious for everyone. But obtaining results with least possible variance is extremely important. variance reduction methods usedfor achieving exact results with less calculating time. Up to now in the MCNP codes, many methods have been utilized for reducing the variance. One of the methods which have recently attracted attentions is using the importance function. For obtaining importance function we need to solve the... 

Magnetic resonance imaging (MRI) is a highly efficient method that can provide acceptable contrast between soft tissues. But the big disadvantage of this method is that its acquisition is slow. To find the reason of being time-consuming should the procedure be surveyed. In the magnetic resonance imaging, location information obtained using phase and frequency encoding gradients. So the output is matrix of image data in the frequency domain, which is called k space. For the formation of the k space phase, need to apply gradients several times and this is the main reason of dullness of the system. Therefore, in this project using software methods try to reduce the scan time as possible. Among... 

Natural disasters, earthquakes in particular, claim many human lives and damage major lifelines such as transportation networks. Transportation networks play an important role in various stages of response to disasters, such as evacuation, search, rescue and reconstruction missions. Hence, special attention must be paid to transportation networks in any disaster management system. Hence, in order to reduce the impacts of earthquakes on denser cities and metropolitan areas, analysis of the resiliency and vulnerability of critical infrastructures such as transportation network, can be used as an effective strategy.The resiliency and vulnerability of transportation network have attract a lot... 

This study will examine the interests of Iran in entering one of the largest and most outreaching LNG markets which is China. In order to examine these interests, understanding China's policy on importing LNG and the competitive environment in this market is necessary. First, the decision theory is used to simulate China's policy on adjusting the import mix during the demand growth period of 2011 to 2017.This provides a simulated picture of its policy on increasing demand for the 2020. Then, the behavior of other LNG exporting countries to China is analyzed using game theory approach. By analyzing the sensitivity of the parameters in which uncertainty exist, it was revealed that Iran's... 

As a problem, generally, energy security components do not interfere with the calculation of the optimal energy supply situation. In this paper, we are looking to find a solution to make a framework of the impact of energy security on energy supply in order to obtain comprehensive analysis of the economic optimal point. Method is based on the competition of energy costs to meet demand during the study period. Threats that have been addressed in the energy security are seen as risky and stochastic parameters in the model. The nature of these parameters is of uncertainty type, therefore, based on the probable scenarios of the stochastic model, the perspective of the energy supply system is... 

One of the actions taken to mitigate the climate change is research, development and demonstration (RD&D) investments in renewable energy technology. In addition to domestic R&D spending, the importation of foreign technologies, as a main channel of technology transfer, is another option to obtain renewable energy technologies in order to achieve climate objectives. In this study, a panel dataset of 28 OECD member countries from 2011 to 2020 is analysed, using the OLS, fixed-effects, and two-system system GMM methods, to assess the impacts of public spending on renewable energy RD&D and the import of renewable energy technologies on the energy-related CO2 emissions. To fully capture the the... 

The aim of this paper is to investigate the effects of Iranian Chief Executive Managers and board of directors on the outcomes of their firms. First, by exploiting the information about changes in the combination of managers in 488 firms in Tehran Stock Exchange and Iran Fara Bourse, this study seeks to give an insight about managers’ labor market in Iran. Then, after combining these data with the obtained information from the firms’ financial statements, we run a set of regressions to identify whether managers have significant effect on the firms’ behaviors and performance. The results of this investigation show that a significant portion of changes in firms’ outcomes can be explained by... 

Nowadays diversion of products from authorized distribution channels to the gray markets has been considered by manufacturers. There many cases that the products of main industries are supplied through gray markets. Gray markets are divided into two categories. The first category is parallel imports where an unauthorized distributor or a third party imports the products from a low price market into a market with high price. In most researches of parallel importation it is assumed that a monopoly manufacturer distributes its products in both two markets. In the second category of parallel importation researches, it is assumed that the manufacturer distributes the products in a certain market... 

Governments use tariff and non-tariff import barriers for several reasons including protecting national industries, tax income and or checking the quality of imported products. These barriers motivate importers to make a profit through smuggling. This study focuses on “import tariff rate” as a main motivation for smuggling and tries to estimate the elasticity of smuggling with respect to tariff rates. Iran trade flow data and tariff rates are collected from Trademap, WITS, Iran’s customs administration and Iran’s Trade Development Organization. By observing reported exports to Iran from main trade partners together with reported imports to Iran we construct a proxy for the amount of... 

In recent years, displacement is more considered in comparison with force in design of structures. For example in 2800 standard -3rd edition- it is stated that for the reason that real displacement of structure in linear analysis is not calculable; it is necessary to resonate the lateral displacement of elastic analysis with a coefficient which is related to behavior coefficient of structure. This displacement should be less than allowable limit that is noted in the code. In similar foreign codes importance factor is also noted beside behavior factor in calculation of real lateral displacement of structure. Evaluation of this coefficient for different structures, comparison with suggested... 

Network coding is realized to have great potential for improving the performance of uncoordinated distributed networked storage, and also cooperative content distribution networks (Peer-to-Peer networks). In these kinds of systems, file is stored or dispensed in blocks which can be the coded version of the original blocks of the file. The existing network coding scheme in P2P networks (Avalanche) finds coding opportunities and uses them in forwarding en-coded blocks through the network. This scheme uses the swarming technique and network coding together, in a single transmission, and consequently, it achieves several fold increase in the throughput of P2P networks. In this thesis, we have... 

It is inevitable to simulate the phenomena that govern nature to make decisions and policies on water and environmental issues. Therefore, researchers have tried to make a good prediction of water's quantitative and qualitative status by using modeling and computer processing power. One of the primary and essential issues in modeling is using sensitivity analysis techniques. Using this knowledge, much information will be obtained on how to influence the model's output regarding various factors such as parameters, input data, and initial and boundary conditions. Global sensitivity analysis based on variance as one of the most well-known and, at the same time, the most widely used sensitivity... 

Identification of different hazards in a UF6 production process, and evaluation of the risk originated from these hazards is the main objective of this project. A number of hazards are present in a typical UF6 production process, such as leakage of chemical gases like HF and F2 and also radioactive UF6 gas release. In order to evaluate risk due to these hazards, probabilistic approach has been used. Due to lack of probabilistic safety criteria (PSC) for chemical releases, only for UF6 gas release risk assessment has been done. As a first step in PSA of this process eight groups of initiating events have been identified using HAZOP study, and for each initiating event, event tree analysis... 

In general, release of hazardous gas in chemical process plants could be due to two reasons. First is failures due to degradation of components that have inventory of hazardous gas in standard process conditions, and the second is deviation of system from standard process conditions because of different failure modes of related components, e.g. controller equipments. The purpose of this study is, calculating the probability of H2S releasing in GS(03) plant of Arak Heavy Water factory, using PSA methods and its risk assessment. At First, fifteen groups of initiating events were identified with Hazop study for desired system. Then, for calculating the frequency of each event, the combination... 

Determining the failure rate or reliability of a system's subsystems, is an important and influential stage which is noteworthy not only in design and in manufacture phases but also in improvement phase. This process is called reliability allocation in literature. Reliability allocation guarantees more reliable and competitive product. The consequence of considering this phase in designing a product is to improve designing and manufacturing methods. As a result, it is possible to gain cheap and reliable product while is compatible with costumer's demands. Many factors and parameters which exist in the process of reliability allocation, have caused it to complicated process. A number of... 

The commodity market as a noteworthy section of the capital market plays a prominent role in the economy of a nation. Base metals, which are widely utilized as industrial raw materials, account for a part of the costs imposed on a nation’s economy. Hence the price levels and volatility of such metals have been under close observation by the capital markets and in the process of monetary policy. In this research we investigate the impacts of the monetary policy of the Federal Reserve on the return of base metals based on daily data and also on the stock return of the corporates which are associated with these metals by using intraday data. This poster employs Federal Funds Futures Contracts...