Sharif Digital Repository

In most countries Frequency control services as one of the Ancillary services are presented in market scheme. Frequency control are used in different levels to balance generation and demand. Each reserve levels is implemented with specific characteristics and rules. Clearance of energy and one control reserve has some drawbacks so in this thesis we try to clear energy and different reserve levels simultaneously. Each reserve level is determined with special criteria. This criterion in primary reserve is frequency deviation restriction and unit commitment risk in territory reserve that is determined by system operator. In this thesis these two criteria are formulated in linear form and... 

By comparing the control systems, researcherstypically believe that the active systems of control have better performance than passive ones. However, the high costs and the required technology for their erection and maintenance have limited the use of active control systems. In order to improve the control system performance at lower costs, semi-active control systems were also considered. Their performance is based on creating the desired control force by changing the instrument characteristics.Moreover, recent researches have shown that the improved performance of these instruments in structures compared to passive control systems, are typically due to reducing the flexibility of the... 

A tensile-compression ring is derived from the spoke wheel principle. The wheel is one of the greatest inventions in mankind. The use of the wheel has developed through time. Engineers found out that the use of the spoke wheel as a roof structure provides many benefits. With the spoke wheel principle a lightweight, cost-efficient roof structure can be made. In recent years the spoke wheel principle has also been applied for oval shaped roofs in order to increase the application of the principle. An example is the use of the roof structure for football stadia. The problem is that the spoke wheel principle will only work at full extend when its shape is completely circular. The question rises... 

To study the interaction between energy sector and the Iranian economy, an energy-economy model has been developed which itself is a part of an integrated model of Energy Planning Support System (EPSS). The model is a dynamic computable general equilibrium (DCGE) model which evaluates the medium to long-term economic developments through investment decisions. Four groups of economic agents have been considered: households, firms, governments and foreign sectors. The economic behavior of each agent along with the institutional links among them has been modeled based on neoclassical theory of general equilibrium. Therefore, the model simulates the working of a market economy and solves for a... 

One important problem in query optimization in centralized and decentralized databases is optimizing queries containing common sub-expressions, known as multi-query optimization. In processing these queries, the goal is to process a group of queries together and find a global execution plan with minimum cost for the query set. In most of researches which have approached this problem the focus were on exhaustive algorithms. Since size of the problem space for these algorithms grows exponential with query set size, these approaches are impractical. In this research we have presented six algorithms based on Ant Colony Optimization metaheuristic. We have compared the efficiency of these methods... 

The increasing rate of population and agricultural development over the past few decades has led to a significant rise in the pollution of surface and groundwater. The application of animal and synthetic fertilizers containing phosphorus, which increases the levels of this element in the soil, can be considered one of the factors endangering the environment, especially the quality of surface waters. The transport of phosphorus, which is one of the pollutants in agricultural runoff, can lead to the degradation of aquatic ecosystems and reduce the quality and usability of water resources. Accordingly, various numerical models have been developed to simulate phosphorus loss from the soil. They... 

The rise in carbon dioxide levels has led to the manifestation of numerous environmental challenges. Currently, the absorption and conversion of carbon dioxide into valuable fuel resources such as synthetic gas, methane, and ethylene are deemed crucial from both environmental and economic standpoints. Despite the presentation of photocatalysts such as titanium oxide and electrocatalysts such as copper, silver, and zinc, their efficiency in CO2 conversion is found to be insufficient. One potential solution to this problem is the utilization of photoelectrocatalytic CO2 recovery. In this study, the aim was to enhance the photoelectrocatalytic reduction of CO2 by designing and manufacturing... 

At the early stages of production, oil reservoirs may have enough energy to push the oil from the reservoir into the wellbore and subsequently from the wellbore to the surface. When the reservoir energy is too low for the well to flow, or the production rate desired is greater than the reservoir energy can deliver, using some kind of artificial lift method to provide the energy to bring the fluid to the surface, seems to be necessary. Continuous flow gas lift is one of the most common artificial lift methods widely used in the oil industry during which, at appropriate pressure, gas is injected in a suitable depth into the tubing to gasify the oil column, and thus assist the production. Each... 

The development of alternative energy sources is a prominent area of scientific research. Hydrogen, with its exceptional energy density, has emerged as a particularly promising candidate among these new energy sources. An effective technique for generating hydrogen is through the electrochemical process of water splitting. To enhance this process, it is crucial to investigate the development of electrocatalysts with high electrocatalytic activity. Among the potential options, sulfides of transition metals show promise. An essential difficulty in electrochemical water splitting is the development of a bifunctional catalyst that is both active and stable for both the hydrogen evolution... 

For policy and decision makers, controlling pollution emissions are a real challenge. The best way to collect fiscal resources, optimal distribution of them to developing businesses in optimal energy production and reducing emissions, are important issues to be decided. Finding a monetary value emissions imposing to community is a key point to find out how they are affecting the whole economy and this will help decision makers to conduct better road maps and policies. Many different approaches and methodologies are used in literature to find appropriate answers to above mentioned questions and phenomena, in this research, integrated assessment modeling methodology is used, an economical... 

With occurring severe earthquakes, damages of columns in RC buildings can lead to overall failure and collapse. So retrofitting of such columns that do not comply with the design requirements is necessary to prevent such phenomena. A variety of methods has been introduced so far for retrofitting. The key factors in determining the retrofitting methods are being economic and easily implemented in the design. Confining concrete columns with pre-stressed steel strips is a new technique that is simple and economic. Previous experimental experiments have shown that this method can enhance ductility and overall seismic behavior of such columns.
In the present study three and six story frames... 

Digital image analysis of histological datasets is a currently expanding field of research. Histological images are inherently complex in nature and contain a wide variety of visual information. Graph-based methods have recently gained immense popularity, as these methods can effectively describe tissue architecture and provide adequate numeric information for subsequent computer-based analysis. Graphs have the ability to represent spatial arrangements and neighborhood relationships of different tissue components, which are essential characteristics observed visually by pathologists during the investigation of specimens. In this thesis, we proposed an automatic approach for classification... 

Engineering of properties was previously not possible. With the advent of additive manufacturing, it became possible to produce structures with architected microstructures, known as lattice structures. The popularity of these structures, due to their lightweight and tunable properties, has increased the importance of their optimal mechanical analysis. Since direct analysis of these structures is computationally prohibitive due to their high level of detail, homogenization methods have been proposed as an alternative. Since these methods couldn't capture size effects, higher-order homogenization methods were introduced. However, despite their good accuracy, these methods are still rarely used...