Sharif Digital Repository

The subsidies targeting law was ratified on October 23, 2009. At mentioned law appointed that the government redistributes up to 50% of earned revenues from price reforming of energy carriers to households by cash and non-cash payments and 30% of earned revenues to the production sector. But reports studies indicate that from 2010 to 2016, the government allocated 93.4% of the revenues to households in cash and non-cash and only 0.7% to the production sector. It can, therefore, be concluded that the subsidies targeting law has not been properly implemented. Indeed, the government has not only failed to fully reform energy carriers prices, but also has increased the households’ share of... 

In present research, a new system of energy extraction from water flow has been studied and optimized. This semi-active energy harvesting system consists of an airfoil that is connected to the generator by an arm. The passage of water causes the airfoil to move, so the hydrodynamic forces on the airfoil will cause the arm to move and finally the generator. In this research, complete dynamic modeling of this energy extraction system including generator, airfoil, controller and actuator modeling is presented and the governing dynamic equations are extracted using this modeling for dynamic simulation. Two dimensional fluid simulations have also been performed using fluent software. Finally, in... 

The Oil and gas industry is one of the most important industries in the world. It has great role in Iran’s economy also. Regarding complexities of new companies, there is room for more cooperation and coordination within the industry and with other actors. Oil and gas niches have close interdependency with financial sector. The new encrypted currencies play great role in new financial models. Blockchain technology can help the oil and gas industry by using its appropriate features. Blockchain is a system of recording information in a way that makes it difficult or impossible to change, hack, or cheat the system. The supply chain of oil and gas industry in Iran includes upstream, midstream... 

Due to rising demand of Natural gas in the global market and expected natural gas production soar in Iran which holds largest natural gas reserved in the world, addressing the optimal allocation of natural gas resources considering the role of Iran in global trade is of utmost importance to researchers as well as policy makers . The aim of this research is to develop a decision making tool which optimally allocate the natural gas resources. To develop this tool, qualitative and quantitative models of Multi-Criteria decision making considering energy security, economic and environment criteria are coupled to find the bests alternative options of natural gas exploration and the economic... 

Developers have been spending a lot of time on program comprehension during software evolution. Program comprehension reduces the cost and the software development time and increases maintainability of a program. However, the lack of documentation makes this process exhausting. Source code summarization is one of the existing solutions to help developers understand a program. Source code summarization gives an opportunity for the developers to better understand the source code by spending less time. There are a lot of approaches for source code summarization. For instance, exploiting knowledge of the crowd, information retrieval, deep neural networks, or using eye tracking of developers... 

Proper documentation plays an important role in successful software management and maintenance. Software repositories such as GitHub host an enormous number of software entities with various features. Developers collaboratively implement, use, and share these repositories in the community. Software repositories use issue tracking systems to keep track of issue reports, both to manage workload and document the highlight of teams’ effort. An issue report can contain a request for new features, a reported problem, or simply a question by users of a software product. As the number of these issues increases, it becomes harder to manage them. Github provides labels for tagging issues, however,... 

Developers often seek to find projects that match their topics of interest in version control systems with the goal of reusing code, extracting similar requirements, learning, and more. However, due to the widespread use of these systems, the number of projects maintained on them is huge and ever-increasing. This has made it difficult to identify projects based on their topics. GitHub, as a prominent version control system, with the aim of facilitating access to projects based on their topics, has provided the possibility of assigning software topics to projects in the form of free-text tags for users. Assigning a correct and complete set of topics to software projects allows programmers to... 

As one of the most important software artifacts, release reports include most essential changes of software systems in each release. These reports are useful for documenting team activities, improving communication between team members and facilitating decision makings. They are often generated manually by a team member, which can be a tedious and time-consuming task. For each release, one should go through hundreds of issue reports, changed files, source code, and other related documents to determine what has changed and why. Then they need to identify the most important and relevant changes. Therefore, automated generation of release reports can be highly desirable. Despite the... 

In this study, the physic of an unsteady flow surrounding two oscillating airfoils in tandem configuration at low Reynolds-numbers has been simulated in a 2D manner by utilizing the Sliding-mesh approach and K-ω-SST turbulent model in Ansys-Fluent application. The first step in this study is selecting the decent numerical grid and flow solution scheme. After choosing the proper solution for this problem, next is to verify the methodology with respect to the references. In the next step, The tandem configuration and pitching motion of the airfoils is being implemented with existing tools and the flow structure, leading-edge and trailing-edge vortex shedding and blade-vortex interactions is... 

Software requirements are changing continuously and hence during software evolution and maintenance, source codes changes are being committed in the software repositories. Reading source codes to understand the changes is a very time consuming and tedious activity. Commit messages contain information about code changes that let developers be aware of the essence of the changes without reading the source codes. Unfortunately, due to the pressure of deadlines and lack of time, developers neglect to write these messages. Commit messages can speed up the process of software understanding for developers and also play an important role in software documentation. Therefore, an automated method for... 

Iran has the second largest natural gas resources in the world and these rich resources provide Iran with good potential for exporting natural gas but so far this potential has not been used well. In contrast, India is a major importer of these energy carriers due to high energy consumption and low level of energy production, especially oil and natural gas production, and continues to increase its imports so that its natural gas imports in 2018 equals 30 billion cubic meters, the IEA expects to reach 85 billion cubic meters by 2040. So the two countries can complement each other in the field of natural gas, such as crude oil and have close relations.In this study, using AHP, Iran's gas... 

In recent years, the number of applications in app stores such as Google Play has increased dramatically. In Google Play, people can write a review and give a rate to each application. Each review contains a lot of notable information such as ‘feature request’ which helps with software maintenance. Also, the user rate is a sign of user satisfaction or dissatisfaction. Users can change their reviews and rate anytime they want. The previous studies show that total rating affects the success of apps and the total number of downloads. They also found that a lot of users take the rating as one of the important factors while downloading the app and they usually don’t download the apps which have... 

Undoubtedly, energy is one of the most important components of progress in any country. Despite some existing imagery about the future of human access to new and non-renewable energy sources, it is now safe to say that energy is a limited resource that is becoming increasingly difficult to access over time. Utilizing the experiences of developed countries in the field of optimal management and advancing strategic goals in the field of energy is one of the necessities of the country today. In this dissertation, using the meta-combined method, the experiences of the United States of America, China, Saudi Arabia, Norway, Singapore and India as countries that each have one of the advantages in... 

The purpose of this study is to analyze the economic, welfare, and environmental effects of the policy of reforming energy subsidies in the industrial sector. The policy of reforming energy subsidies has been examined in the form of 6 scenarios based on the elimination of the current system of payment and redistribution of income among households and producers in certain proportions using a computable general equilibrium model. In the static model, economic variables include variables of production, price and net exports at the industry level and GDP variables, consumer price index, household consumption, government spending, investment, total imports and exports, prices and employment of... 

According to increasing energy demand in Iran and the world, the role of natural gas as a relatively clean and cost-effective source has received more attention. Given the high share of the residential sector in the country's natural gas consumption, providing a model for forecasting the demand of this sector is of great importance for policy makers and decision makers in this field. In the present study, we employ three popular methods of machine learning, support vector regression, artificial neural network and decision tree to predict the consumption of natural gas in the residential sector in Tehran according to meteorological parameters (including temperature, precipitation and wind... 

Software quality assurance activities such as debugging are considered one of the most important and effective tasks in software development life cycle. However, these activities are tedious and time consuming. Consequently, wide variety of studies have been conduced around the process of software debugging, such as predicting defects,which is one of the most important topics in this area.In spite of the popularity of software libraries and frameworks, and the use of application programming interfaces (API), most of the studies in the defect prediction area have not focused on predicting defects related to API usages. However, due to the lack of documentation and complexity of the APIs... 

The length of time a user plays a computer game is one of the most important metrics for a game’s success in the gaming industry. The importance of this metric can be explained from the viewpoint of different actors present in this industry, for example, from the point of view of the game Developer, increasing the duration of the playtime leads to an increase in opportunity for further in-game marketing, gamers value this metric since it entails how long can a game can entertain them. Making sure that a game can be entertaining for a long period of time is one of the most important factors in choosing to buy a game. Also, it’s in every online store’s best interest to always offer games to... 

Energy harvesting is a process in which energies in nature are recycled on a small scale and used to power equipment such as sensors, data recorders and transmitters, IoT monitoring and applications. Recently, energy harvesting from a new model based on movements caused by vortices of wind and water flow has been considered. The fall of unstable vortices behind the body induces aero-hydrodynamic forces into the body. If the body has degrees of freedom of movement, the vortex phenomenon can cause the body to rotate or rotate, resulting in energy extraction. Previous studies show that very little activity has been done so far on energy extraction from the Stall flutter phenomenon. The main... 

Increasing the kinetic energy of the near-wall fluid by exciting shear layers is known as an effective method for flow separation control. So far, choosing the proper approach to apply excitations has been a challenging issue in the field of flow control. This work investigates flow control of airfoils in static stall and flutter conditions, employing shear layer excitation technique and plasma actuators. This research introduces a novel flow separation control, namely dual-point excitation of shear layers and compares its performance with the conventional single-point excitation method. Two airfoils (NACA 4415 and NACA 0015) have been considered as the baseline test-cases. In the first part... 

Many pieces of evidence of climate change show that humanity should be concerned about the future of its life and the planet. The concentration of carbon dioxide in the atmosphere has reached its highest level. Therefore, in recent years, the reduction of publications and climate issues has been on the agenda of governments. For this reason, governments and various international organizations are looking for a way to change and reform the global energy system. Forecasts indicate a decrease in the share of fossil fuels and an increase in the percentage of renewable energies and hydrogen. Hydrogen has been introduced as the future fuel carrier due to its many advantages such as the...